2N2222 Zener noise
Bitrex
feeling lazy I thought I'd check first: By how much do you have to
reverse bias the emitter-base junction of a common transistor such as
the 2N2222 before it starts getting appreciably noisy? Does it have to
be above the 5-6 volt breakdown voltage, or will significant noise occur
before that point? I'm looking for a noise source that will work with a
3 volt supply. Maybe a different transistor with a lower breakdown voltage?
Bill Sloman
You are snookered by the physics. Reverse-biased diodes break down by
two different mechanisms depending on the voltage applied acorss the
junction, the Zenner (quantum tunneling) mechanism at alow voltages -
less than 5V - and the avalanche (impact ionisation) mechanism at
higher voltages.
http://ecee.colorado.edu/~bart/book/book/chapter4/ch4_5.htm
Avalanche breakdown gives a noisier leakage current than quantum
tunnelling - with avalanche breakdown there is always the chance that
an electron will make it all the way across the gap without generating
a second electron-hole pair, killing the leakage current until a
cosmic ray or a radioative atom in the vicinity generates a new charge
carrier pair to restart the avalanche process. Quantum mechanical
tunnelling is also a random process, but it is a single random
process, without the second stage of avalanche multipication to
generate lots of outliers.
With a 3V supply rail you are stuck with Zener breakdown. You may have
to settle for a pseudo-random binary sequence generator, or amplifying
the Johnson noise from a resistor - 1nV per root hertz for a 50R
resistor at room temerature, rising as the square root of the
resistance, bearing in mind that "low noise" integrated circuit op
amps typically also generate 1nV per root hertz white noise at room
temperature.
--
Bill Sloman, Nijmegen
Bitrex
Thanks for your reply and for the enlightenment regarding the difference
between breakdown mechanisms. Instead of trying to amplify Johnson
noise, perhaps I can use a spare opamp section of the project as a
hysteretic oscillator and make a charge pump to kick the voltage up
above the 5 volt threshold? I wonder if a low voltage op amp like the
LM324 acting as a charge pump would be able to get the voltage high
enough to initiate the avalanche breakdown mode - I'm not sure what the
'324's output can swing at such low voltages, but I bet getting 5 volts
with a 3 volt supply with such a circuit might be pushing it.
Jamie
zener mode and impact mode is a balance at 5 volts and anything under
that goes into "impact" mode and above is zener. Looking at the behavior
of the commonly known 5.1 Vref diode where a diode is in series with the
zener stabilizes the effects between the two.
I think you may want to do a better job of memorizing that document
you red before posting your proclaimed expertise drivel.
If it were me, I would've suggested to look at a "NOISE DIODE" and not
throw a crap load of physics that you most likely barely understand.
Things like SHot and Johnson Noise could also be a good help as
references to loop up..
Now, I've seen some tricks done using a tunnel diodes in my day..
Jamie.
Joerg
> On Nov 26, 9:26 am, Bitrex <bit...@de.lete.earthlink.net> wrote:
[...]
> With a 3V supply rail you are stuck with Zener breakdown. You may have
> to settle for a pseudo-random binary sequence generator, or amplifying
> the Johnson noise from a resistor - 1nV per root hertz for a 50R
> resistor at room temerature, rising as the square root of the
> resistance, bearing in mind that "low noise" integrated circuit op
> amps typically also generate 1nV per root hertz white noise at room
> temperature.
>
Dudes, dudes ... what is so difficult about making a higher voltage from 3V?
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
John Larkin
You win't find a transistor that zeners at 3 volts. Well, maybe an
exotic microwave one.
Do you need high-quality, flat, Gaussian noise?
How about doing it digitally, with a pseudo-random shift register?
John
Bill Sloman
> zener mode and impact mode is a balance at 5 volts and anything under
> that goes into "impact" mode and above is zener.
Then you had better go and get yourself a better education.
> Looking at the behavior of the commonly known 5.1 Vref diode where a diode is in series with > the zener stabilizes the effects between the two.
You would be thinking of the 1N821 through 1N829 6.2V voltage
reference diodes, which did include a a forward diode to compensate
for the temperature coefficient of a 5.6V "zener" diode.
http://www.datasheetcatalog.org/datasheet/motorola/1N823.pdf
http://206.209.106.106/datasheets/Zeners/AppNotes.pdf
The breakdown voltage you get with a pure zener (quantum tunnelling)
mechanism decreases with increasing temperature, while an avalanche
breakdown voltage increases with increasing temperature. At 5.6V the
balance between the two mechanisms favours the avalanche route enough
that the voltage across the reverse biassed diode increases by the
same 2mV/K that the voltage across the forward diode decreases.
http://en.wikipedia.org/wiki/Zener_diode
> I think you may want to do a better job of memorizing that document
> you red before posting your proclaimed expertise drivel.
Since you managed to confuse the the 5.1V "zener" diode, which has a
roughly zero temperature coefficient, with the 6.2V reference diodes
which do include a forward diode, your own advice can be seen as less
than reliable.
> If it were me, I would've suggested to look at a "NOISE DIODE" and not
> throw a crap load of physics that you most likely barely understand.
Google doesn't throw up much on noise diodes. The nearest thing to
something useful came from here
http://www.electronicspoint.com/noise-diode-t23382.html
> Things like Shot and Johnson Noise could also be a good help as
> references to look up..
I did refer to Johnson noise. Google on that and you get to
http://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise
which does include a reference to shot noise.
http://en.wikipedia.org/wiki/Shot_noise
Neither is going to be of much help to the OP, who wants a solution to
a problem - not the education that you obviously failed to absorb.
> Now, I've seen some tricks done using a tunnel diodes in my day..
The real trick with tunnel diodes today is finding where you can buy
one. The difficulty with tunnel diodes is that they are broadband
devices. If you don't mount them in a properly designed transmission
line environment, they will oscillate at a frequency your oscilliscope
can't follow, and the voltage levels that you will see - at
frequencies that your oscilliscope can follow - won't look anything
like what you wanted and expected.
--
Bill Sloman, Nijmegen
Kevin McMurtrie
Bitrex <bit...@de.lete.earthlink.net> wrote:
Are MOVs noisy? Luxeon Rebel LEDs flicker in the 2V/microamp range,
which I'm hoping is their MOV rather than defects in the chip slowly
burning away.
--
I will not see posts or email from Google because I must filter them as spam
Mr.CRC
What on earth is flat Gaussian noise?
A flat, ie. even distribution is not a Gaussian, so perhaps I'm
misunderstanding this statement. Please enlighten...
BTW, the new Agilent 3352x arb. generators have a nice feature that lets
you adjust the bandwidth of the noise, which is Gaussian.
They also have a LFSR noise generator, but it's not analog but rather
on/off. I guess if it were to be analog, it would have to let you
select some number of bits to gather for each output. This would give a
flat analog noise. It would have been nice if you could select the
distribution of the noise. Perhaps I'll send these ideas on to Agilent.
They have been very nice to me over the years, taking many of my ideas
directly to the scope and generator prod. devel. managers.
It can also use the noise to modulate a PWM signal, so coupled with a
little flyback pulse generator, can be used to simulate a lot of jittery
physical phenomena, like laser pulses.
--
_____________________
Mr.CRC
crobc...@REMOVETHISsbcglobal.net
SuSE 10.3 Linux 2.6.22.17
Ian Field
"Bitrex" <bit...@de.lete.earthlink.net> wrote in message
news:XcCdnet8IpWVNHLR...@earthlink.com...
It'd probably be easier to get a single transistor blocking oscillator to
work, the charge pump gives just under Vccx2, if you need more you have to
cascade doubler stages.
For a one-off you could liberate the erase oscillator from a scrap cassette
deck - the inductor is usually styled like an IFT, so nice neat finished
job.
Tim Williams
> I bet getting 5 volts with a 3 volt supply with such a circuit might be
> pushing it.
LM324? Yuck, you'll be lucky to get anything at all...
You'd be better off with a blocking oscillator, which only takes another
transistor and can be made with a common transformer, nothing custom
needed. Depending on supply regulation, you may need to consider a
control loop, which will add a few transistors to the total.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Tim Williams
news:icp82...@news3.newsguy.com...
> BTW, the new Agilent 3352x arb. generators have a nice feature that lets
> you adjust the bandwidth of the noise, which is Gaussian.
The bandwidth is gaussian? :-)
Now... is it gaussian over linear or logarithmic frequency? That could be
handy... And a kurtosis adjustment to tweak the band skirts...
Tim Williams
news:6d92f745-9c69-486c...@z9g2000yqz.googlegroups.com...
>> If it were me, I would've suggested to look at a "NOISE DIODE" and not
>> throw a crap load of physics that you most likely barely understand.
>
Reading the appendix in one of my ARRL handbooks, I remember seeing a
strange device. IIRC, diode with 2.5V 2A filament, 100V or so plate,
waveguide connection. It was a thermionic saturation noise diode. So it
worked from shot noise of emitted electrons, and current was controlled by
filament temperature. The characteristic of such a device is
constant-current above a certain voltage. I guess it was good enough for
a few dB of noise in the microwave band (>1000MHz?). I'll have to see if
I can find what number it is.
Rich Grise
> On 11/26/2010 6:26 AM, Bill Sloman wrote:
>> On Nov 26, 9:26 am, Bitrex<bit...@de.lete.earthlink.net> wrote:
>>> I suppose I could set things up to do the research myself, but since I'm
>>> feeling lazy I thought I'd check first: By how much do you have to
>>> reverse bias the emitter-base junction of a common transistor such as
>>> the 2N2222 before it starts getting appreciably noisy?
>> http://ecee.colorado.edu/~bart/book/book/chapter4/ch4_5.htm
>>
>> Avalanche breakdown gives a noisier leakage current than quantum
>> tunnelling - with avalanche breakdown there is always the chance that
>> an electron will make it all the way across the gap without generating
>> a second electron-hole pair, killing the leakage current until a
>> cosmic ray or a radioative atom in the vicinity generates a new charge
>> carrier pair to restart the avalanche process. Quantum mechanical
>> tunnelling is also a random process, but it is a single random
>> process, without the second stage of avalanche multipication to
>> generate lots of outliers.
>>
>> With a 3V supply rail you are stuck with Zener breakdown. You may have
>> to settle for a pseudo-random binary sequence generator, or amplifying
>> the Johnson noise from a resistor - 1nV per root hertz for a 50R
>> resistor at room temerature, rising as the square root of the
>> resistance, bearing in mind that "low noise" integrated circuit op
>> amps typically also generate 1nV per root hertz white noise at room
>> temperature.
>
> between breakdown mechanisms. Instead of trying to amplify Johnson
> noise, perhaps I can use a spare opamp section of the project as a
> hysteretic oscillator and make a charge pump to kick the voltage up
> above the 5 volt threshold? I wonder if a low voltage op amp like the
> LM324 acting as a charge pump would be able to get the voltage high
> enough to initiate the avalanche breakdown mode - I'm not sure what the
> '324's output can swing at such low voltages, but I bet getting 5 volts
> with a 3 volt supply with such a circuit might be pushing it.
What ever happened to Watson A Name's micropower switchers for LEDs? I
don't remember what he called them, but it's one transistor, a ferrite
core and a few resistors and caps.
I wonder how "good" a noise source just a piece of wire dangling in the air
might be, picking up random radio, TV, and telephone signals? You'd need a
sharp filter at your local line frequency, of course.
I also wonder if it would work to use the ion source from an ionizing smoke
detector?
Good Luck!
Rich
Mr.CRC
> "Mr.CRC" <crobc...@REMOVETHISsbcglobal.net> wrote in message
> news:icp82...@news3.newsguy.com...
>> BTW, the new Agilent 3352x arb. generators have a nice feature that lets
>> you adjust the bandwidth of the noise, which is Gaussian.
>
> The bandwidth is gaussian? :-)
>
> Now... is it gaussian over linear or logarithmic frequency? That could be
> handy... And a kurtosis adjustment to tweak the band skirts...
Pardon my ambiguous wording.
The noise is temporally gaussian. The high-pass cutoff bandwidth may be
set.
Noise with configurable parametric band shape would be quite impressive,
but unfortunately not yet available in generators of this caliber.
The main improvement of this gen. over the competing Tek AFG30xx series,
aside from the usual generational improvements in memory and sampling
rate, is that the new Agilent has a finely adjustable sampling rate for
arbs., making it a true arbitrary waveform architecture, vs. just an
arbitrary function generator, which has a fixed sampling rate, ie., the Tek.
There is a special discount for the 2 channel model until mid January.
After buying two for work, I'm tempted to buy one for home. Trouble is,
I spent too much this year on numeric display tubes and now fixing my
car :-(
Joerg
Do you mean Joule-Thief?
> I wonder how "good" a noise source just a piece of wire dangling in the air
> might be, picking up random radio, TV, and telephone signals? You'd need a
> sharp filter at your local line frequency, of course.
>
John Larkin has something suitable right there, he probably just needs a
paperclip stuck into a BNC jeck to get tons of random signal from Sutro
Tower.
> I also wonder if it would work to use the ion source from an ionizing smoke
> detector?
>
Wouldn't necessarily have that on my lab table :-)
John Larkin
<crobc...@REMOVETHISsbcglobal.net> wrote:
>John Larkin wrote:
>> On Fri, 26 Nov 2010 03:26:21 -0500, Bitrex
>> <bit...@de.lete.earthlink.net> wrote:
>>
>>> I suppose I could set things up to do the research myself, but since I'm
>>> feeling lazy I thought I'd check first: By how much do you have to
>>> reverse bias the emitter-base junction of a common transistor such as
>>> the 2N2222 before it starts getting appreciably noisy? Does it have to
>>> be above the 5-6 volt breakdown voltage, or will significant noise occur
>>> before that point? I'm looking for a noise source that will work with a
>>> 3 volt supply. Maybe a different transistor with a lower breakdown voltage?
>>
>> You win't find a transistor that zeners at 3 volts. Well, maybe an
>> exotic microwave one.
>>
>> Do you need high-quality, flat, Gaussian noise?
>
>What on earth is flat Gaussian noise?
Flat in the frequency doamin, Gaussian in probability distribution,
like really good noise should be.
>
>A flat, ie. even distribution is not a Gaussian, so perhaps I'm
>misunderstanding this statement. Please enlighten...
>
>
>BTW, the new Agilent 3352x arb. generators have a nice feature that lets
>you adjust the bandwidth of the noise, which is Gaussian.
We have a couple of 8-channel ARBs that do that, too. Here's one:
http://www.highlandtechnology.com/DSS/T346DS.shtml
We use a DDS channel to clock a digital random number generator and
also clock a downstream digital lowpass filter. So the RMS voltage is
independent of the noise bandwidth. Everything just rubberbands in
time.
>They also have a LFSR noise generator, but it's not analog but rather
>on/off. I guess if it were to be analog, it would have to let you
>select some number of bits to gather for each output. This would give a
>flat analog noise. It would have been nice if you could select the
>distribution of the noise. Perhaps I'll send these ideas on to Agilent.
> They have been very nice to me over the years, taking many of my ideas
>directly to the scope and generator prod. devel. managers.
>
>It can also use the noise to modulate a PWM signal, so coupled with a
>little flyback pulse generator, can be used to simulate a lot of jittery
>physical phenomena, like laser pulses.
We can do that too! Also AM, FM, PM, summing, and complex combinations
of all the above. That was fun to design.
John
John Larkin
Buy our 8 channel version!
John
Jamie
Yeah sure, I take my education religiously, and use it. You on
the other hand, are just blowing smoke. You better check your
references again.
>
>>Looking at the behavior of the commonly known 5.1 Vref diode where a diode is in series with > the zener stabilizes the effects between the two.
>
>
> You would be thinking of the 1N821 through 1N829 6.2V voltage
> reference diodes, which did include a a forward diode to compensate
> for the temperature coefficient of a 5.6V "zener" diode.
>
> http://www.datasheetcatalog.org/datasheet/motorola/1N823.pdf
>
> http://206.209.106.106/datasheets/Zeners/AppNotes.pdf
>
What a blow hard...
Save your breath, it only shortens your life..
rest of this non-sense is deleted..
Jamie.
Jamie
Yeah sure, I take my education religiously, and use it. You on
the other hand, are just blowing smoke. You better check your
references again.
>
>>Looking at the behavior of the commonly known 5.1 Vref diode where a diode is in series with > the zener stabilizes the effects between the two.
>
>
> You would be thinking of the 1N821 through 1N829 6.2V voltage
> reference diodes, which did include a a forward diode to compensate
> for the temperature coefficient of a 5.6V "zener" diode.
>
> http://www.datasheetcatalog.org/datasheet/motorola/1N823.pdf
>
> http://206.209.106.106/datasheets/Zeners/AppNotes.pdf
>
k...@att.bizzzzzzzzzzzz
Well, like ALwaysWrong, you are always wrong.
Zener breakdown occurs at less than ~6V. Avalanche breakdown above (the two
balance at about 6V). *Avalanche* mode is the "impact" mode where the
electric field accelerates electrons such that when they hit atoms they knock
free more electrons, which are accelerated hitting more atoms... That's why
it's an "avalanche". Zener breakdown is tunneling.
http://people.seas.harvard.edu/~jones/es154/lectures/lecture_2/breakdown/breakdown.html
>>>Looking at the behavior of the commonly known 5.1 Vref diode where a diode is in series with > the zener stabilizes the effects between the two.
>>
>>
>> You would be thinking of the 1N821 through 1N829 6.2V voltage
>> reference diodes, which did include a a forward diode to compensate
>> for the temperature coefficient of a 5.6V "zener" diode.
>>
>> http://www.datasheetcatalog.org/datasheet/motorola/1N823.pdf
>>
>> http://206.209.106.106/datasheets/Zeners/AppNotes.pdf
>>
>What a blow hard...
> Save your breath, it only shortens your life..
>
> rest of this non-sense is deleted..
YOu should have snipped a few dozen lines higher.
Jamie
Another miss informed idiot..
I understand why they blow up at you.. You're just a waste of
BW.
Mr.CRC
> On Fri, 26 Nov 2010 13:16:05 -0800, "Mr.CRC"
> <crobc...@REMOVETHISsbcglobal.net> wrote:
>
>> John Larkin wrote:
>>> On Fri, 26 Nov 2010 03:26:21 -0500, Bitrex
>>> <bit...@de.lete.earthlink.net> wrote:
>>>
>>>> I suppose I could set things up to do the research myself, but since I'm
>>>> feeling lazy I thought I'd check first: By how much do you have to
>>>> reverse bias the emitter-base junction of a common transistor such as
>>>> the 2N2222 before it starts getting appreciably noisy? Does it have to
>>>> be above the 5-6 volt breakdown voltage, or will significant noise occur
>>>> before that point? I'm looking for a noise source that will work with a
>>>> 3 volt supply. Maybe a different transistor with a lower breakdown voltage?
>>> You win't find a transistor that zeners at 3 volts. Well, maybe an
>>> exotic microwave one.
>>>
>>> Do you need high-quality, flat, Gaussian noise?
>> What on earth is flat Gaussian noise?
>
> Flat in the frequency doamin, Gaussian in probability distribution,
> like really good noise should be.
>
Oh, ok we're on the same wavelength after all.
>
> We have a couple of 8-channel ARBs that do that, too. Here's one:
>
> http://www.highlandtechnology.com/DSS/T346DS.shtml
>
> We use a DDS channel to clock a digital random number generator and
> also clock a downstream digital lowpass filter. So the RMS voltage is
> independent of the noise bandwidth. Everything just rubberbands in
> time.
>
> We can do that too! Also AM, FM, PM, summing, and complex combinations
> of all the above. That was fun to design.
>
> John
>
Where are the knobs and display? Is there a good ready-made PC GUI
program to control it? Or is it a very straightforward terminal command
set that I can learn in a few minutes?
Sample memory isn't very deep. But arb. isn't my usual application. 4
channels is a plus, since I may want to tinker with 3 and 4-phase stuff.
What's the sample rate for the freq. ranges?
What are the sine wave distortion specs in the audio range?
I like the fine phase setting. I have a need for about 0.01 degree
resolution for a PLL system at work. But I think my system already has
it built in. I have to check what phase resolution is possible with the
uC based frequency source in that.
What about external inputs for AM, FM, PM, PWM, summing, etc.?
Can I externally trigger pulses? Can I set a pre-delay? What
resolution? Burst mode with 1, N, or infinite pulses? What is minimum
pulse width? Are edge rates configurable?
Please send me a quote and a manual if possible. Please decode email
address below.
Robert Baer
6V and typically you will see 8V or more despite literature "specs"
saying they ALL are 5V.
You definitely will never see 3V breakdown of standard "sand power"
transistors.
Maybe if you get into the exotic microwave, HEMT, etc stuff...
k...@att.bizzzzzzzzzzzz
Yeah, the whole world is wrong, except DimBulb and Jamie. We got it.
> I understand why they blow up at you.. You're just a waste of
> BW.
Information is not a waste of bandwidth. You, OTOH,...
John Larkin
Certainly not white noise. Nearly all opamps have a 1/f noise corner.
John
John Larkin
<crobc...@REMOVETHISsbcglobal.net> wrote:
The serial comm protocol is very simple. We do have a PC gui thing,
but it doesn't support all the features.
>
>Sample memory isn't very deep. But arb. isn't my usual application. 4
>channels is a plus, since I may want to tinker with 3 and 4-phase stuff.
>
>What's the sample rate for the freq. ranges?
The DDSs always run at 128 MHz. It also does sample interpolation,
from the waveform mamory up to the 128 MHz DACs, which somewhat
mitigates the small memories. All the wavegen stuff is onboard a
Xilinx FPGA, which limits memory size.
>
>What are the sine wave distortion specs in the audio range?
Around -60. What was really hard was to keep the distortion down below
-50 or so all the way to 32 MHz. It's not unusual to see RF signal
generators with -20 dB distortion specs.
>
>I like the fine phase setting. I have a need for about 0.01 degree
>resolution for a PLL system at work. But I think my system already has
>it built in. I have to check what phase resolution is possible with the
>uC based frequency source in that.
>
>What about external inputs for AM, FM, PM, PWM, summing, etc.?
We didn't do that. Maybe next spin.
>
>Can I externally trigger pulses? Can I set a pre-delay? What
>resolution? Burst mode with 1, N, or infinite pulses? What is minimum
>pulse width? Are edge rates configurable?
Yes, mostly. I'll email you the manual. One thing you can do is use
the memory of one channel to build a microengine the sequences other
channels, to do really complex stuff.
>
>
>
>Please send me a quote and a manual if possible. Please decode email
>address below.
OK.
John
John Larkin
Some silicon microwave transistors have very low rated max reverse
Vbe, which may be an artifact of their very abrupt junctions. I'll
measure some next week, maybe.
I've seen PNP silicon transistors that zenered at around 12 volts.
John
Tim Williams
news:88idnVxdoOYG4G3R...@posted.localnet...
> You definitely will never see 3V breakdown of standard "sand power"
> transistors.
> Maybe if you get into the exotic microwave, HEMT, etc stuff...
Not that unusual. Regular silicon in the 1GHz range will zap under 5V.
Find them all the time in video amps and such.
Bitrex
> "Bitrex"<bit...@de.lete.earthlink.net> wrote in message
> news:XcCdnet8IpWVNHLR...@earthlink.com...
>> I'm not sure what the '324's output can swing at such low voltages, but
>> I bet getting 5 volts with a 3 volt supply with such a circuit might be
>> pushing it.
>
> LM324? Yuck, you'll be lucky to get anything at all...
>
should be possible to use it with a 3V lithium ion coin cell as the supply.
> You'd be better off with a blocking oscillator, which only takes another
> transistor and can be made with a common transformer, nothing custom
> needed. Depending on supply regulation, you may need to consider a
> control loop, which will add a few transistors to the total.
>
> Tim
>
I think I'm going to use that approach. I experimented with some
blocking oscillator circuits in LTSpice today and I think I've found a
setup that will generate a high enough voltage to produce avalanche
noise from a reverse biased emitter-base junction. I had to experiment
with putting some series resistance before the circuit to prevent it
boosting to a ridiculously high voltage with a light load, and drawing
so much current that it drags down the supply across the coin cells
relatively high ESR. For better efficiency I may put in a simple
base-current robbing control loop as you suggest.
LM
> 6V and typically you will see 8V or more despite literature "specs"
> saying they ALL are 5V.
> You definitely will never see 3V breakdown of standard "sand power"
> transistors.
> Maybe if you get into the exotic microwave, HEMT, etc stuff...
I once measured some BF199 transistors and it felt like they had BE
breakdown voltage about 1V or so.
Jamie
for Vbe
Looks like a general purpose component..
Jamie.
Bill Sloman
<k...@att.bizzzzzzzzzzzz> wrote:
> On Fri, 26 Nov 2010 21:38:14 -0500, Jamie
>
>
>
> <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
> >k...@att.bizzzzzzzzzzzz wrote:
> >> On Fri, 26 Nov 2010 21:11:50 -0500, Jamie
>
> >>>BillSlomanwrote:
>
> >>>>>Looking at the behavior of the commonly known 5.1 Vref diode where a diode is in series with > the zener stabilizes the effects between the two.
>
> >>>>You would be thinking of the 1N821 through 1N829 6.2V voltage
> >>>>reference diodes, which did include a a forward diode to compensate
> >>>>for the temperature coefficient of a 5.6V "zener" diode.
>
> >>>>http://www.datasheetcatalog.org/datasheet/motorola/1N823.pdf
>
> >>>>http://206.209.106.106/datasheets/Zeners/AppNotes.pdf
>
> >>>What a blow hard...
> >>> Save your breath, it only shortens your life..
>
> >>> rest of this non-sense is deleted..
>
> >> YOu should have snipped a few dozen lines higher.
>
> > Another miss informed idiot..
>
> Yeah, the whole world is wrong, except DimBulb and Jamie. We got it.
>
> > I understand why they blow up at you.. You're just a waste of
> > BW.
>
> Information is not a waste of bandwidth. You, OTOH,...
Jamie has achieved something remarkable. He's got krw agreeing with
me, and me agreeing with krw.
This implies that Jamie has has posted something that really is
remarkably stupid. If there was any room for a difference of opinion,
it can be taken as read that krw and I would disagree, but Jamie has
managed to reach hitherto unplumbed depths of stupidity.
--
Bill Sloman, Nijmegen
Bill Sloman
For bipolar op amps the noise corner is close to 10Hz. You don't have
to leave your frequency window open much above 10Hz for the white
noise to swamp the 1/f noise, and you can always high-pass filter the
noise to get rid of the 1/f contribution.
--
Bill Sloman, Nijmegen
Bill Sloman
BFR92 has a base-emitter reverse breakdown voltage of 2V. It is a
broadband part, but Farnell stocks it and has 7153 in stock at a price
equivalent to $0.61 each, which is pretty close to a "sand power"
transistor. IIRR most cheap broad-band transistors have similarly low
base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
the same 2V specification.
--
Bill Sloman, Nijmegen
Joerg
The BFP620 has a 1.2V abs max rating for Vbe and Digikey has them in
stock for around a buck in small qties.
At 65GHz ft this one can be considered a hotrod.
John Larkin
Most are higher than that, if it's specified at all. And opamps can
have very non-Gaussian behavior, like temperature driven offsets,
popcorn noise, ambient RF rectification, PSRR issues. An opamp isn't a
very good noise source. A zener can make several hundred nV/rthz of
pretty high quality noise. A PN shift register is almost perfect.
John
John Larkin
Is that the abs max datasheet spec, or an actual, typical zener
voltage?
Lots of RF parts have very conservative reverse voltage ratings. We
use schottky diodes at -6 volts, that are rated for -2.
John
Jan Panteltje
<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
<67m2f69u8ue6o3m7h...@4ax.com>:
>>transistor. IIRR most cheap broad-band transistors have similarly low
>>base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
>>the same 2V specification.
>
>Is that the abs max datasheet spec, or an actual, typical zener
>voltage?
>
>Lots of RF parts have very conservative reverse voltage ratings. We
>use schottky diodes at -6 volts, that are rated for -2.
>
>John
Long time ago there was a discussion here about degradation of RF transistors
when used as zeners, from that arises the question how long
such a RF transistor would last as a zener,
Joerg
It probably lasts a long time. However, a transistor that had been used
as a zener with their BE path should not be put back into the parts bin.
There can be deterioration in it's normal job function, as a transistor.
John Larkin
I've done a little testing. Zener voltage seems to change (down, I
seem to recall) over time but seems to settle out after, say, a week
at a few mA. I assume the transistor action suffers.
John
Jamie
No, it means the both of you are confused. Don't count your chickens
boy, before they hatch..
P.S.
Yes, you need all the help you can get, so fitting for him to
join in. Good luck with that one.
Jamie
what constitutes high quality noise? I've never heard it put that way! :)
Noise is noise, be it white, pink, brown and your analogy "Popcorn",
first time I've heard that one ect !
Jan Panteltje
<jjla...@highNOTlandTHIStechnologyPART.com> wrote in
<9st2f6hr34mqblnm7...@4ax.com>:
I assume you mean a few volt?
John Larkin
Good noise approximates a physical, random process. Different defects
matter to different people. The RF boys want spectral flatness. Crypto
people want zero predictability. Process people might want a nearly
Gaussian PD. Audio folks don't want audible defects, like hum or
popcorn noise or detected RF.
>
> Noise is noise, be it white, pink, brown and your analogy "Popcorn",
>first time I've heard that one ect !
Look it up.
John
Gerhard Hoffmann
o $0.61 each, which is pretty close to a "sand power"
>> transistor. IIRR most cheap broad-band transistors have similarly low
>> base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
>> the same 2V specification.
>
> Is that the abs max datasheet spec, or an actual, typical zener
> voltage?
Probably data shhet spec. Bringing BE to breakdown ruins the low noise
property of a transistor.
For example, in the Infineon npn BC847-850 and pnp BC857-860 series, the
BC850 / 860 subtypes are guaranteed for noise and
promptly have reduced Vbe specs IIRC. I assume the whole familly
is made on the same process, maybe same wafers.
> Lots of RF parts have very conservative reverse voltage ratings. We
> use schottky diodes at -6 volts, that are rated for -2.
Most of my customers would blacklist you for admitting that.
Gerhard
John Larkin
<pNaonSt...@yahoo.com> wrote:
>On a sunny day (Sat, 27 Nov 2010 13:28:33 -0800) it happened John Larkin
><jjla...@highNOTlandTHIStechnologyPART.com> wrote in
><9st2f6hr34mqblnm7...@4ax.com>:
>
>>On Sat, 27 Nov 2010 20:07:35 GMT, Jan Panteltje
>><pNaonSt...@yahoo.com> wrote:
>>
>>>On a sunny day (Sat, 27 Nov 2010 11:17:43 -0800) it happened John Larkin
>>><jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>>><67m2f69u8ue6o3m7h...@4ax.com>:
>>>
>>>>>transistor. IIRR most cheap broad-band transistors have similarly low
>>>>>base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
>>>>>the same 2V specification.
>>>>
>>>>Is that the abs max datasheet spec, or an actual, typical zener
>>>>voltage?
>>>>
>>>>Lots of RF parts have very conservative reverse voltage ratings. We
>>>>use schottky diodes at -6 volts, that are rated for -2.
>>>>
>>>>John
>>>
>>>Long time ago there was a discussion here about degradation of RF transistors
>>>when used as zeners, from that arises the question how long
>>>such a RF transistor would last as a zener,
>>
>>I've done a little testing. Zener voltage seems to change (down, I
>>seem to recall) over time but seems to settle out after, say, a week
>>at a few mA. I assume the transistor action suffers.
>
>I assume you mean a few volt?
I don't have my data here, but I recall a BCX70 running around 8 volts
Vbe zener voltage, and changing maybe a tenth of a volt over a few
days.
Gathering some better data, including beta degradation, would be an
ideal project for some unemployed PhD.
John
Jamie
That's interesting, I did look that up, and it appears to be another
name of something I was already aware of.. I read a parcel on
Wki and it mention behavior of defects found in transistors.
I did have a batch of smt 2222's that would not work in linear
applications, only switching because at a specific current (Ice) No
mater the configuration, I was getting a small noise that could be seen
via scope in the collector circuit. You go below or above this current
point and it would go away.. When I set the scope up to expand the view
on that section, I go what looked like a random oscillation.
I used a spectrum analyzer on that point and got random noise that
started around 100hz up to about 1 mhz.. It would change just by varying
the bias slightly.
I have since replaced that batch and all is well once again.
MMBT2222 iirc...
k...@att.bizzzzzzzzzzzz
Did you even READ the link I posted? That Harvard prof says you're full of
shit, too. ...but of course you know more than everyone.
> P.S.
> Yes, you need all the help you can get, so fitting for him to
>join in. Good luck with that one.
To tell any newbs here that you're chronically full of shit, sure. I'm more
than happy to help.
John Larkin
wrote:
The schottky in question is intended for RF detector use, so there's
no reason the vendor should spec them past -2. They probably don't
even test for it.
To get really high performance, especially speed, you have to stress
parts. The trick is to test them carefully and back off some prudent
amount. Schottkies, fortunately, just leak more as voltage goes up,
and if there's not a lot of current available, there's probably no
long-term degradation mechanism. No problems so far.
Lots of parts, especially RF stuff, are simply missing key specs, so
all you can do is test.
Sloppy design within ratings probably kills more circuits than the
occasional, thoughtfully considered spec push. Lots of tantalum caps,
for example, have exploded into flames while operating well within
their specs.
John
Gerhard Hoffmann
> John Larkin wrote:
>
> That's interesting, I did look that up, and it appears to be another
> name of something I was already aware of.. I read a parcel on
> Wki and it mention behavior of defects found in transistors.
>
> I did have a batch of smt 2222's that would not work in linear
> applications, only switching because at a specific current (Ice) No
> mater the configuration, I was getting a small noise that could be seen
> via scope in the collector circuit. You go below or above this current
> point and it would go away.. When I set the scope up to expand the view
> on that section, I go what looked like a random oscillation.
>
> I used a spectrum analyzer on that point and got random noise that
> started around 100hz up to about 1 mhz.. It would change just by varying
> the bias slightly.
Popcorn noise is short bursts of very loud noise caused by
contamination with heavy metal ions. Much like the sound
of popcorn in statu nascendi. In the 1974 RCA intgegrated
circuits data book there was an app note on how to measure it.
PCN is no problem in products from better manufacturers nowadays.
regards, Gerhard
Joerg
> On Sat, 27 Nov 2010 23:41:51 +0100, Gerhard Hoffmann <dk...@arcor.de>
> wrote:
>
>> Am 27.11.2010 20:17, schrieb John Larkin:
[...]
>>
>>> Lots of RF parts have very conservative reverse voltage ratings. We
>>> use schottky diodes at -6 volts, that are rated for -2.
>> Most of my customers would blacklist you for admitting that.
>
Gerhard, sometimes the envelope needs to be pushed. I doubt the Space
Shuttle would have ever flown if they would not have done that. Yeah, it
does carry a risk. But as they say, no risk, no reward. The risk can be
minimized. For example, in the case of a Schottky used past limits you
make sure no excess current can flow and, if needed, there are redundant
system so the mission can be completed.
> The schottky in question is intended for RF detector use, so there's
> no reason the vendor should spec them past -2. They probably don't
> even test for it.
>
> To get really high performance, especially speed, you have to stress
> parts. The trick is to test them carefully and back off some prudent
> amount. Schottkies, fortunately, just leak more as voltage goes up,
> and if there's not a lot of current available, there's probably no
> long-term degradation mechanism. No problems so far.
>
> Lots of parts, especially RF stuff, are simply missing key specs, so
> all you can do is test.
>
Very popular: Frequency range 100MHz to xGHz. Upon contacting the mfgs
it often turns out that they simply did not measure below 100MHz so they
had no data. So they cut the spec there but it runs all the way down to DC.
> Sloppy design within ratings probably kills more circuits than the
> occasional, thoughtfully considered spec push. Lots of tantalum caps,
> for example, have exploded into flames while operating well within
> their specs.
>
Oh yeah. I remember the words of a production tech: "There was a loud
bang, and then it was like popcorn".
John Larkin
<jamie_ka1lpa_not_v...@charter.net> wrote:
Popcorn noise is super low frequency and is usually seen in the form
of discrete/bimodal level shifts, like the output of a random pulse
generator. It's common for it to look like pulses, milliseconds in
duration, milliseconds to seconds apart, or random in time level
shifts. Sometimes a part will sit quietly for hours and then let out a
burst. The magnitude is in the ballpark of 10s of microvolts RTI. The
cause is supposedly ionic contamination in oxide layers or something.
It's named because it sounds like corn popping.
Analog Devices has an appnote where they claim it's a thing of the
past. They should test some of their own DACs.
John
Joerg
[popcorn noise]
> Popcorn noise is super low frequency and is usually seen in the form
> of discrete/bimodal level shifts, like the output of a random pulse
> generator. It's common for it to look like pulses, milliseconds in
> duration, milliseconds to seconds apart, or random in time level
> shifts. Sometimes a part will sit quietly for hours and then let out a
> burst. ...
That would be called a silicon fart :-)
> ... The magnitude is in the ballpark of 10s of microvolts RTI. The
> cause is supposedly ionic contamination in oxide layers or something.
> It's named because it sounds like corn popping.
>
> Analog Devices has an appnote where they claim it's a thing of the
> past. They should test some of their own DACs.
>
You mean like the claim a long time ago that the recession is over? Or
that increasing public employee pensions by 50% will have no noticeable
effect on the asset levels of pension funds?
Gerhard Hoffmann
> To get really high performance, especially speed, you have to stress
> parts. The trick is to test them carefully and back off some prudent
> amount. Schottkies, fortunately, just leak more as voltage goes up,
> and if there's not a lot of current available, there's probably no
> long-term degradation mechanism. No problems so far.
>
> Lots of parts, especially RF stuff, are simply missing key specs, so
> all you can do is test.
OK, but the wording then has to be like
"We took the burden to re-characterize the part in this non-standard
environment" and not "the mfg says -2, but -6 seems to work" :-)
(my 1st language is not English)
> Sloppy design within ratings probably kills more circuits than the
> occasional, thoughtfully considered spec push. Lots of tantalum caps,
> for example, have exploded into flames while operating well within
> their specs.
For NEC and other reputable mfgs the spec says 1/3 Ohm per Volt
source resistance, and then they won't explode.
Gerhard
Gerhard Hoffmann
>> Analog Devices has an appnote where they claim it's a thing of the
>> past. They should test some of their own DACs.
>
> You mean like the claim a long time ago that the recession is over? Or
> that increasing public employee pensions by 50% will have no noticeable
> effect on the asset levels of pension funds?
Can't you keep this political liqui-shit out of sci.electronics.design?
This group could be really interesting, but that 95% of "left-wing" vs
"AmeriNazi" content makes it just useless.
Gerhard
Bill Sloman
So you are not only stupid, but also young.
http://en.wikipedia.org/wiki/Burst_noise
Not only the 709 but also the 741 suffered from thos problem
http://odyssea.cps.unizar.es/~te/Docencia_archivos/d_sheets/ao/fn531.pdf
RCA even went to the trouble of making a version of the 741 with a
popcorn noise specification.
I've been assured that modern 741's don't have this problem, but
around 1988 I appreciably improved the performance of the Cambridge
Instruments/ Metals Research Gallium Arsenide Crystal Puller by
replacing one uA741 with an OP-07, which does happen to have a
popocorn noise specification.
I did quite a bit more to the machine's electronics, but the absence
of popcorn noise made a very perceptible difference to the way the
machine performed, and probably reduced the residual thermal stresses
in the single-crystal GaAs that the machine produced (roughly 95% of
the single cyrstal GasAs produced in the west at the time).
--
Bill Sloman, Nijmegen
Bill Sloman
You would.
I'm quoting the data-sheet specification. I'm well aware that even a
little reverse break-down of a base-emitter junction can degrade the
forward current gain of a transistor, and I've heard the story about
the HP technicians who used to "repair" metal-cased output transistors
by stubbing their cigarettes out on the device - it provided just
enough thermal annealing to get rid of the worst of the damage.
I never had the occasion to destroy a broad-band transistor by finding
out it's actual reverse breakdown voltage.
--
Bill Sloman, Nijmegen
Bill Sloman
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 27 Nov 2010 22:04:41 GMT, Jan Panteltje
>
>
>
> <pNaonStpealm...@yahoo.com> wrote:
> >On a sunny day (Sat, 27 Nov 2010 13:28:33 -0800) it happened John Larkin
> ><9st2f6hr34mqblnm7gma33m7p5vfd6l...@4ax.com>:
>
> >>On Sat, 27 Nov 2010 20:07:35 GMT, Jan Panteltje
> >><pNaonStpealm...@yahoo.com> wrote:
>
> >>>On a sunny day (Sat, 27 Nov 2010 11:17:43 -0800) it happened John Larkin
> >>><67m2f69u8ue6o3m7hbu4ra5pan06l3i...@4ax.com>:
>
> >>>>>transistor. IIRR most cheap broad-band transistors have similarly low
> >>>>>base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
> >>>>>the same 2V specification.
>
> >>>>Is that the abs max datasheet spec, or an actual, typical zener
> >>>>voltage?
>
> >>>>Lots of RF parts have very conservative reverse voltage ratings. We
> >>>>use schottky diodes at -6 volts, that are rated for -2.
>
> >>>>John
>
> >>>Long time ago there was a discussion here about degradation of RF transistors
> >>>when used as zeners, from that arises the question how long
> >>>such a RF transistor would last as a zener,
>
> >>I've done a little testing. Zener voltage seems to change (down, I
> >>seem to recall) over time but seems to settle out after, say, a week
> >>at a few mA. I assume the transistor action suffers.
>
> >I assume you mean a few volt?
>
> I don't have my data here, but I recall a BCX70 running around 8 volts
> Vbe zener voltage, and changing maybe a tenth of a volt over a few
> days.
>
> Gathering some better data, including beta degradation, would be an
> ideal project for some unemployed PhD.
If he had the gear and the transistors. Electronics is an expensive
hobby.
--
Bill Sloman, Nijmegen
Michael A. Terrell
Then take a sledge hammer to your computer, before you kill yourself
over it.
--
For the last time: I am not a mad scientist, I'm just a very ticked off
scientist!!!
Jamie
You know any one can sit there and copy paste all day long... You
wouldn't even be here if it wasn't for the internet allowing you access
to that material. You would be just another loser to your community just
pissing in the wind.
And young, no. I grew up in days of tubes, germanium, the first
generation of IC's you twit..
And burst noise I know, I just never heard it called popcorn noise..
You ugly maggot..
I bet you don't know your real mother, she most likely gave you to
the orphanage at birth.
Gerhard Hoffmann
> Then take a sledge hammer to your computer, before you kill yourself
> over it.
My computer is ok, and my barrier to killing someone
is probably higher than yours.
> For the last time: I am not a mad scientist, I'm just a very ticked
> off scientist!!!
That probably should read: "I am not a mad scientist, I'm just
mad!!!11eleven1!!"
Gerhard
John Larkin
Yeah, a DVM, a few resistors, an old wall-wart power suply, and a few
assorted transistors might cut into your palate educating budget.
John
John Larkin
I do! And charge for it!
>
>I'm quoting the data-sheet specification. I'm well aware that even a
>little reverse break-down of a base-emitter junction can degrade the
>forward current gain of a transistor, and I've heard the story about
>the HP technicians who used to "repair" metal-cased output transistors
>by stubbing their cigarettes out on the device - it provided just
>enough thermal annealing to get rid of the worst of the damage.
>
>I never had the occasion to destroy a broad-band transistor by finding
>out it's actual reverse breakdown voltage.
We have reels of them. The slow gumdrop transistors cost a few cents.
Pretty impressive RF parts cost $0.25 to 0.75 typically. Way, way down
in the noise, so to speak.
It would be interesting to try a microwave transistor E-B zener as a
super-wideband noise generator. Most official, expensive noise diodes
are more in the 10 volt range.
John
Gerhard Hoffmann
> It would be interesting to try a microwave transistor E-B zener as a
> super-wideband noise generator. Most official, expensive noise diodes
> are more in the 10 volt range.
Have done that with a BFR93 / 96. Was completely flat to at least
2.5 GHz. Could not test more at the Weinheim ham meeting.
Now, I'v got a calibrated Agilent noise source to 26 Ghz, so
it's no longer interesting for me except as a built-in self test.
Gerhard
Rich Grise
> On Nov 27, 11:57 pm, John Larkin
>>
>> ideal project for some unemployed PhD.
>
> If he had the gear and the transistors. Electronics is an expensive
> hobby.
>
Cheers!
Rich
Michael A. Terrell
Gerhard Hoffmann wrote:
>
> Am 28.11.2010 02:09, schrieb Michael A. Terrell:
>
> > Then take a sledge hammer to your computer, before you kill yourself
> > over it.
>
> My computer is ok, and my barrier to killing someone
> is probably higher than yours.
Yawn.
> > For the last time: I am not a mad scientist, I'm just a very ticked
> > off scientist!!!
>
> That probably should read: "I am not a mad scientist, I'm just
> mad!!!11eleven1!!"
Why would I use gibberish, I'm not European. I don't know why, but
Europeans get all bent out of shape over sig files.
--
John Larkin
I don't suppose there's an ebay equivalent in the Netherlands. Or a
Harbor Freight Salvage. It's amazing what you can get on ebay these
days.
One of the guys here bought a spectrum analyzer on ebay, and we
received it and shipped it to him in Italy.
John
Jan Panteltje
<bill....@ieee.org> wrote in
<c367b7f8-ee11-4629...@w2g2000yqb.googlegroups.com>:
>On Nov 27, 11:57�pm, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> On Sat, 27 Nov 2010 22:04:41 GMT, Jan Panteltje
>>
>>
>>
>> <pNaonStpealm...@yahoo.com> wrote:
>> >On a sunny day (Sat, 27 Nov 2010 13:28:33 -0800) it happened John Larkin
>> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
>> ><9st2f6hr34mqblnm7gma33m7p5vfd6l...@4ax.com>:
>>
>> >>On Sat, 27 Nov 2010 20:07:35 GMT, Jan Panteltje
>> >><pNaonStpealm...@yahoo.com> wrote:
>>
>> >>>On a sunny day (Sat, 27 Nov 2010 11:17:43 -0800) it happened John Lark=
>in
>> >>><jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
>> >>><67m2f69u8ue6o3m7hbu4ra5pan06l3i...@4ax.com>:
>>
>> >>>>>transistor. IIRR most cheap broad-band transistors have similarly lo=
>w
>> >>>>>base-emitter breakdown voltages. It's PNP complement - the BFT92 - h=
>as
>> >>>>>the same 2V specification.
>>
>> >>>>Is that the abs max datasheet spec, or an actual, typical zener
>> >>>>voltage?
>>
>> >>>>Lots of RF parts have very conservative reverse voltage ratings. We
>> >>>>use schottky diodes at -6 volts, that are rated for -2.
>>
>> >>>>John
>>
>> >>>Long time ago there was a discussion here about degradation of RF tran=
>sistors
>> >>>when used as zeners, from that arises the question how long
>> >>>such a RF transistor would last as a zener,
>>
>> >>I've done a little testing. Zener voltage seems to change (down, I
>> >>seem to recall) over time but seems to settle out after, say, a week
>> >>at a few mA. I assume the transistor action suffers.
>>
>> >I assume you mean a few volt?
>>
>> I don't have my data here, but I recall a BCX70 running around 8 volts
>> Vbe zener voltage, and changing maybe a tenth of a volt over a few
>> days.
>>
>> Gathering some better data, including beta degradation, would be an
>> ideal project for some unemployed PhD.
>
>If he had the gear and the transistors. Electronics is an expensive
>hobby.
This can be done with a 5 Euro meter, a 1 cent resistor, and a 2 Euro battery.
if you have no money for the battery, use the one in the meter,
and subtract (simple math is free).
I bought 20 BC557B transistors for 1 Euro last week, that is retail.
Want the address?
Somebody said here something like:
Engineering is the art of making new things from the things you have.
That does not have to be expensive.
But OK you will need a soldering iron, brain, solder, well...
I guess we will have to wait then.
>--
>Bill Sloman, Nijmegen
>
>
Ian Field
"Bitrex" <bit...@de.lete.earthlink.net> wrote in message
news:Gaadnbf0v_bfVm3R...@earthlink.com...
> On 11/26/2010 4:59 PM, Tim Williams wrote:
>> "Bitrex"<bit...@de.lete.earthlink.net> wrote in message
>> news:XcCdnet8IpWVNHLR...@earthlink.com...
>>> I'm not sure what the '324's output can swing at such low voltages, but
>>> I bet getting 5 volts with a 3 volt supply with such a circuit might be
>>> pushing it.
>>
>> LM324? Yuck, you'll be lucky to get anything at all...
>>
> It is cheap! Also, it supposedly works down to 2.3 volts, so it should
> be possible to use it with a 3V lithium ion coin cell as the supply.
>
>> You'd be better off with a blocking oscillator, which only takes another
>> transistor and can be made with a common transformer, nothing custom
>> needed. Depending on supply regulation, you may need to consider a
>> control loop, which will add a few transistors to the total.
>>
>> Tim
>>
>
> I think I'm going to use that approach. I experimented with some blocking
> oscillator circuits in LTSpice today and I think I've found a setup that
> will generate a high enough voltage to produce avalanche noise from a
> reverse biased emitter-base junction. I had to experiment with putting
> some series resistance before the circuit to prevent it boosting to a
> ridiculously high voltage with a light load, and drawing so much current
> that it drags down the supply across the coin cells
How did you connect the base winding?
There's some scope to tweak the limiting resistor in the base circuit to
tame the output without incurring as much loss as a dropper resistor in the
Vcc line.
Excessive output voltage can be turned to advantage by allowing enough
headroom for a constant current circuit - much more stable noise source.
If you use a JFET constant current generator you can include LCR in series
with the current setting resistor to tailor the noise response.
Bill Sloman
>
> >>>>I suppose I could set things up to do the research myself, but since I'm
> >>>>feeling lazy I thought I'd check first: By how much do you have to
> >>>>reverse bias the emitter-base junction of a common transistor such as
> >>>>the 2N2222 before it starts getting appreciably noisy? Does it have to
> >>>>be above the 5-6 volt breakdown voltage, or will significant noise occur
> >>>>before that point? I'm looking for a noise source that will work with a
> >>>>3 volt supply. Maybe a different transistor with a lower breakdown voltage?
>
> >>>two different mechanisms depending on the voltage applied acorss the
> >>>junction, the Zenner (quantum tunneling) mechanism at alow voltages -
> >>>less than 5V - and the avalanche (impact ionisation) mechanism at
> >>>higher voltages.
>
> >>>http://ecee.colorado.edu/~bart/book/book/chapter4/ch4_5.htm
>
> >>>Avalanche breakdown gives a noisier leakage current than quantum
> >>>tunnelling - with avalanche breakdown there is always the chance that
> >>>an electron will make it all the way across the gap without generating
> >>>a second electron-hole pair, killing the leakage current until a
> >>>cosmic ray or a radioative atom in the vicinity generates a new charge
> >>>carrier pair to restart the avalanche process. Quantum mechanical
> >>>tunnelling is also a random process, but it is a single random
> >>>process, without the second stage of avalanche multipication to
> >>>generate lots of outliers.
>
> >>>With a 3V supply rail you are stuck with Zener breakdown. You may have
> >>>to settle for a pseudo-random binary sequence generator, or amplifying
> >>>the Johnson noise from a resistor - 1nV per root hertz for a 50R
> >>>resistor at room temerature, rising as the square root of the
> >>>resistance, bearing in mind that "low noise" integrated circuit op
> >>>amps typically also generate 1nV per root hertz white noise at room
> >>>temperature.
>
> >>zener mode and impact mode is a balance at 5 volts and anything under
> >>that goes into "impact" mode and above is zener.
>
> > Then you had better go and get yourself a better education.
>
> Yeah sure, I take my education religiously, and use it.
So you don't question what you were taught - for fear of being
declared a heretic and burnt at the stake. Unfortunately it seems that
your edcuaton, or at least what you now remember of it, was woefully
inadequate.
> You on the other hand, are just blowing smoke. You better check your
> references again.
You'd like to think so. But before you tell me to check my references
again, you should remind yourself that you didn't post any references
and got your facts wrong.
> >>Looking at the behavior of the commonly known 5.1 Vref diode where a diode is in series with the zener stabilizes the effects between the two.
>
> > You would be thinking of the 1N821 through 1N829 6.2V voltage
> > reference diodes, which did include a a forward diode to compensate
> > for the temperature coefficient of a 5.6V "zener" diode.
>
> >http://www.datasheetcatalog.org/datasheet/motorola/1N823.pdf
>
> >http://206.209.106.106/datasheets/Zeners/AppNotes.pdf
>
> What a blow hard...
> Save your breath, it only shortens your life.. rest of this non-sense is deleted..
It is "non-sense" because it conflicts with what Jamie thinks he
remembers. Pity about that. Not only has he made an idiot of himself
in public, but he reveals that he is too cognitively damaged to
recognise that he has screwed up.
--
Bill Sloman, Nijmegen
Ian Field
"Joerg" <inv...@invalid.invalid> wrote in message
news:8ld82j...@mid.individual.net...
> Jan Panteltje wrote:
>> On a sunny day (Sat, 27 Nov 2010 11:17:43 -0800) it happened John Larkin
>> <jjla...@highNOTlandTHIStechnologyPART.com> wrote in
>> <67m2f69u8ue6o3m7h...@4ax.com>:
>>
>>>> base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
>>>> the same 2V specification.
>>> Is that the abs max datasheet spec, or an actual, typical zener
>>> voltage?
>>>
>>> Lots of RF parts have very conservative reverse voltage ratings. We
>>> use schottky diodes at -6 volts, that are rated for -2.
>>>
>>> John
>>
>> Long time ago there was a discussion here about degradation of RF
>> when used as zeners, from that arises the question how long
>> such a RF transistor would last as a zener,
>
>
> as a zener with their BE path should not be put back into the parts bin.
> There can be deterioration in it's normal job function, as a transistor.
Easy solution - bend the collector lead till it breaks off.
Jim Thompson
wrote:
>Bill Sloman wrote:
>> On Nov 27, 5:22 am, John Larkin
>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>> On Fri, 26 Nov 2010 19:39:57 -0800, Robert Baer
>>>
>>>
>>>
>>> <robertb...@localnet.com> wrote:
>>>> Bitrex wrote:
>>>>> I suppose I could set things up to do the research myself, but since I'm
>>>>> feeling lazy I thought I'd check first: By how much do you have to
>>>>> reverse bias the emitter-base junction of a common transistor such as
>>>>> the 2N2222 before it starts getting appreciably noisy? Does it have to
>>>>> be above the 5-6 volt breakdown voltage, or will significant noise occur
>>>>> before that point? I'm looking for a noise source that will work with a
>>>>> 3 volt supply. Maybe a different transistor with a lower breakdown
>>>>> voltage?
>>>> As far as i know, the lowest breakdown of any silicon E-B junction is
>>>> 6V and typically you will see 8V or more despite literature "specs"
>>>> saying they ALL are 5V.
>>>> You definitely will never see 3V breakdown of standard "sand power"
>>>> transistors.
>>>> Maybe if you get into the exotic microwave, HEMT, etc stuff...
>>> Some silicon microwave transistors have very low rated max reverse
>>> Vbe, which may be an artifact of their very abrupt junctions. I'll
>>> measure some next week, maybe.
>>
>> BFR92 has a base-emitter reverse breakdown voltage of 2V. It is a
>> broadband part, but Farnell stocks it and has 7153 in stock at a price
>> equivalent to $0.61 each, which is pretty close to a "sand power"
>> transistor. IIRR most cheap broad-band transistors have similarly low
>> base-emitter breakdown voltages. It's PNP complement - the BFT92 - has
>> the same 2V specification.
>>
>
>The BFP620 has a 1.2V abs max rating for Vbe and Digikey has them in
>stock for around a buck in small qties.
>
>http://www.infineon.com/dgdl/bfp620.pdf?folderId=db3a30431400ef68011425b291f205c5&fileId=db3a30431400ef680114274deb27072a
>
>At 65GHz ft this one can be considered a hotrod.
Implanted emitters produce high fT, but low reverse Vbe _rating_. I'm
not sure they actually breakdown at 2V, but I know that migration and
degradation begin there.
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Bill Sloman
I got my access to that material before it was available over the
internet as .pdf files. I just posted URLs so that yu ca=ould take
another look at stuff that you shouldn't have forgotten.
> You would be just another loser to your community just
> pissing in the wind.
>
> And young, no. I grew up in days of tubes, germanium, the first
> generation of IC's you twit..
But you can't remember much about any of it. This could be Alzheimer's
which we can't do much about, or a series of small strokes, which
could be helped by more careful control of blood pressure - you should
talk to your doctor.
> And burst noise I know, I just never heard it called popcorn noise..
Sure you did. You just can't remember that any more.
> You ugly maggot..
>
> I bet you don't know your real mother, she most likely gave you to
> the orphanage at birth.
Wrong again. And the sort of brain damage that goes with loss of long
term memory can also damage the victims social skills, making them
more likely to express aggressive and unpleasant ideas, so you really
do need to talk to your doctor.
--
Bill Sloman, Nijmegen
Bill Sloman
The DVM I've got, though it is old and a bit temperamental,and I've
got a handful of wallwarts, some of them offering a range of output
voltages. The resistors I could buy down-town, from the local hobby
shop, but I'd be surprised if they stocked broad-band transistors.
I've paid, and continue paying, to have a business name (Sophia
Electronica) registered with the local chamber of commerce, which
means that I can, in principle, buy stuff from Farnell in the
Netherlands, but there is a hefty minimium order charge. I will soon
need some more lithium-manganese 9V PP3 cells for the smoke detectors
(which I can only get from Farnell) but while the last lot went in
some ten years ago the smoke detectors haven't yet told me that their
batteries need replacing.
--
Bill Sloman, Nijmegen
Bill Sloman
> On a sunny day (Sat, 27 Nov 2010 16:35:06 -0800 (PST)) it happened Bill Sloman
> <c367b7f8-ee11-4629-9d6b-58ac1febd...@w2g2000yqb.googlegroups.com>:
Sure. E-mail it to me. The BC557 - ft 100MHz - isn't a broad-band
transistor, but the right sort of hobby-supplier - one with ham-radio-
oriented customers - should have the BFR92 and BFT92 in stock.
> Somebody said here something like:
> Engineering is the art of making new things from the things you have.
> That does not have to be expensive.
> But OK you will need a soldering iron, brain, solder, well...
> I guess we will have to wait then.
The soldering iron and solder I've got, along with the side-cutters
and the needle-nosed pliers.
There's even some hook-up wire around somewhere. No prototyping board,
but for this job a bird's nest would work fine.
--
Bill Sloman, Nijmegen
Bill Sloman
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sat, 27 Nov 2010 16:33:25 -0800 (PST), Bill Sloman
>
>
>
There's a reason for this, that I laid out in the second post in this
thread. Avalanche breakdown is noisier than quantum mechanical
tunnelling (the Zener mechanism). With avalanche breakdown, you have
not only the shot noise from the separate charge carriers making their
independent way through the device but you also have the statistical
uncertainty in the avalanche multiplication process, where every
charge carrier needs to generate at least one pair of new charge
carriers as it makes its way through the junction.
--
Bill Sloman, Nijmegen
John Larkin
It shocks me that you'd need official permission to buy electronic
parts, or that there would be a big min order. Where's the social
benefit in that? How are kids supposed to play with electronics if
they can't get parts?
What constituency is all this pandering to?
John
George Herold
> I suppose I could set things up to do the research myself, but since I'm
> feeling lazy I thought I'd check first: By how much do you have to
> reverse bias the emitter-base junction of a common transistor such as
> the 2N2222 before it starts getting appreciably noisy? Does it have to
> be above the 5-6 volt breakdown voltage, or will significant noise occur
> before that point? I'm looking for a noise source that will work with a
> 3 volt supply. Maybe a different transistor with a lower breakdown voltage?
You can amplifiy the shot noise of a forward biased diode. (Or light
on a photodiode)
George H.
Jan Panteltje
<bill....@ieee.org> wrote in
<44952edc-e552-42b8...@n10g2000yqd.googlegroups.com>:
>> I bought 20 BC557B transistors for 1 Euro last week, that is retail.
>> Want the address?
>
>Sure. E-mail it to me. The BC557 - ft 100MHz - isn't a broad-band
>transistor, but the right sort of hobby-supplier - one with ham-radio-
>oriented customers - should have the BFR92 and BFT92 in stock.
Check your email.
Bill Sloman
It's not "official permission". Farnell in the Netherlands won't take
orders from anyone who isn't registered as a business with the local
chamber of commerce. It's one of the ways that Dutch wholesalers
distinguish themselves from retailers.
The minimum order isn't all that big - about 25 euro's when I last
looked - and it discourages orders to small to cover the adminstartive
costs of putting them together and sending them out.
> What constituency is all this pandering to?
I don't think than any constituency is being "pandered too". This is
the way Dutch traders behave. They have been evolving this kind of
behaviour for hundreds of years - since before there was a Dutch
Republic - and it seems to work for them.
--
Bill Sloman, Nijmegen
Bill Sloman
> On a sunny day (Sun, 28 Nov 2010 08:21:05 -0800 (PST)) it happenedBillSloman
> <44952edc-e552-42b8-a17d-38da60548...@n10g2000yqd.googlegroups.com>:
>
> >> I bought 20 BC557B transistors for 1 Euro last week, that is retail.
> >> Want the address?
>
> >Sure. E-mail it to me. The BC557 - ft 100MHz - isn't a broad-band
> >transistor, but the right sort of hobby-supplier - one with ham-radio-
> >oriented customers - should have the BFR92 and BFT92 in stock.
>
> Check your email.
Done. Thanks.
Your first supplier - your source of cheap BC577's - doesn't have any
broadband transistors.
The second has BFR91 and BFR96 parts in the old pill-box package,
which is easier to work with than the SMD-packaged BFR92 or BFT92.
Tomorrow I'll see what I can get them to send me.
--
Bill Sloman, Nijmegen
whit3rd
> Avalanche breakdown is noisier than quantum mechanical
> tunnelling (the Zener mechanism). With avalanche breakdown, you have
> not only the shot noise from the separate charge carriers making their
> independent way through the device but you also have the statistical
> uncertainty in the avalanche multiplication
Not the way I see it; the advantage is that avalanche IS GAIN
applied to the shot noise. That gain makes the signal big enough
to dominate any additions in later amplifiers. Without that gain
in the avalanche process, your later amplifiers are equal
and hard-to-characterize additional sources of noise.
Bill Sloman
> On Nov 28, 8:28 am, Bill Sloman <bill.slo...@ieee.org> wrote:
>
> > Avalanche breakdown is noisier than quantum mechanical
> > tunnelling (the Zener mechanism). With avalanche breakdown, you have
> > not only the shot noise from the separate charge carriers making their
> > independent way through the device but you also have the statistical
> > uncertainty in the avalanche multiplication
>
> Not the way I see it; the advantage is that avalanche IS GAIN
> applied to the shot noise.
Not just gain, but statistically variable gain.
> That gain makes the signal big enough
> to dominate any additions in later amplifiers. Without that gain
> in the avalanche process, your later amplifiers are equal
> and hard-to-characterize additional sources of noise.
If you've got shot noise on a current, you need to have it develop
about 50mV across your load resistor (at room temperature) to equal
the Johnson noise in the load resistor. As you increase the resistance
further, the voltage noise generated from the shot noise rises in
direct proportion to the resistance, while the Johnson noise rises as
the square root of the resistance.
It not that difficult to organise your circuit so that the shot noise
is dominant, and also swamps the Johnson noise in the input stage of
you first amplifier.
--
Bill Sloman, Nijmegen
John Larkin
Needing a license from the government to buy parts sounds pretty
official to me.
>
>The minimum order isn't all that big - about 25 euro's when I last
>looked - and it discourages orders to small to cover the adminstartive
>costs of putting them together and sending them out.
Most US distributors seem to manage.
>
>> What constituency is all this pandering to?
>
>I don't think than any constituency is being "pandered too". This is
>the way Dutch traders behave. They have been evolving this kind of
>behaviour for hundreds of years - since before there was a Dutch
>Republic - and it seems to work for them.
But not so well for people who want to design electronics. The USA is
probably the best place to do that.
John
John Devereux
> On Sun, 28 Nov 2010 10:30:51 -0800 (PST), Bill Sloman
> <bill....@ieee.org> wrote:
[...]
>>> It shocks me that you'd need official permission to buy electronic
>>> parts, or that there would be a big min order. Where's the social
>>> benefit in that? How are kids supposed to play with electronics if
>>> they can't get parts?
>>
>>It's not "official permission". Farnell in the Netherlands won't take
>>orders from anyone who isn't registered as a business with the local
>>chamber of commerce. It's one of the ways that Dutch wholesalers
>>distinguish themselves from retailers.
>
> Needing a license from the government to buy parts sounds pretty
> official to me.
You are being obtuse, it is a decision made entirelyu by the company
(Farnell) not to sell to private individuals. That's not official
permission, it is their freedom of choice to choose this marketing
strategy. Stupid though it may seem. I suppose the government could make
laws dictating which entities companies must deal with, is that how it
works in the USA?
>>
>>The minimum order isn't all that big - about 25 euro's when I last
>>looked - and it discourages orders to small to cover the adminstartive
>>costs of putting them together and sending them out.
>
> Most US distributors seem to manage.
>
>>
>>> What constituency is all this pandering to?
>>
>>I don't think than any constituency is being "pandered too". This is
>>the way Dutch traders behave. They have been evolving this kind of
>>behaviour for hundreds of years - since before there was a Dutch
>>Republic - and it seems to work for them.
>
> But not so well for people who want to design electronics. The USA is
> probably the best place to do that.
You just need to know someone in a small company who would be willing to
order a few parts for you, or work in one. Or have your own of course.
I can order from Farnell (a UK company) with no minimum order charge and
free shipping. They regularly send me single items worth far less than
UPS must charge them. Of course they make it back on the larger orders.
--
John Devereux
Winfield Hill
Simply imagining shot noise with gain can't and doesn't work.
Consider a current of 10uA, that's 6.25M electrons per 10ns,
and the random shot-noise variation would be 2500 in 10ns, or
0.04% noise.
Now imagine that each electron is multiplied by 100. Oops, that
can't be right, because now we'd have 625M electrons per 10ns.
OK, so scale back to 62500 electrons per 10ns, and let each of
those turn into 100 by avalanche gain. Now the random "shot"
noise would be 250 "events" per 10ns, or 0.4%.
But in reality the discrepancy is worse than that, much worse.
We've learned that in avalanche, each starting electron actually
starts a "microplasma" channel that conducts a channel current
e.g., 20uA, lasting say 3 to 50ns, and ending abruptly, in under
a ns, as the small nearby capacitance gets discharged and the
local voltage no longer supports avalanche.
Some plasma channel electron-atom collisions emit photons,
some of which create photoelectrons starting more channels
nearby. It's all highly chaotic.
So we end up with an intermittent noisy "oscillation" of current
pulses of quasi-random length. When you look at the waveform
at longer timescales you see the superposition of thousands of
events, which simply looks noisy. But with the right lashup and
equipment you can view individual channels starting and stopping,
sometimes on top of each other.
This topic, with ASCII waveforms, bench circuit-setup details,
theory and literature references, was extensively covered here
on s.e.d. many years ago. You can read all about it.
Bill Sloman
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Sun, 28 Nov 2010 10:30:51 -0800 (PST),BillSloman
The government isn't involved at all. The local chamber of commerce
registers businesses as a convenience to other businesses. As far as I
know, registration - on its own - doesn't have any legal significance.
If you want to get serious, or turn over more than a few thousand
euro's of business in a year, you register yourself as business with
the tax authorities. You then have to collect value-added-tax (VAT in
English, BTW in Dutch) on your sales, subtract the VAT you have to pay
on the stuff you buy and turn over the difference to the tax
authoritees. Hiring people raises the ante again, but I've not
bothered to get into that.
> >The minimum order isn't all that big - about 25 euro's when I last
> >looked - and it discourages orders too small to cover the adminstrative
> >costs of putting them together and sending them out.
>
> Most US distributors seem to manage.
>
> >> What constituency is all this pandering to?
>
> >I don't think than any constituency is being "pandered too". This is
> >the way Dutch traders behave. They have been evolving this kind of
> >behaviour for hundreds of years - since before there was a Dutch
> >Republic - and it seems to work for them.
>
> But not so well for people who want to design electronics. The USA is
> probably the best place to do that.
Says someone who designs electronics in the USA. I've not had much
reason to suppose that US electronics is better than anybody else's.
and in at least two areas I know well - electron microscopes and
electron beam microfabricators - the US machines were less than
impressive.
--
Bill Sloman, Nijmegen
George Herold
Yes! The old discussion was very nice. I liked the article by K.G.
McKay "Avalanche Breakdown in Silicon" Phys. Rev. (94) pg 877. (May
15, 1954) It would be fun to see these different channels start to
conduct as the voltage is raised. There are some temperature effects
which also sound interesting.
(Wouldn't it be nice if these old articles were now part of the public
domain?)
George H.
Phil Hobbs
> On Sat, 27 Nov 2010 09:38:58 -0800 (PST), Bill Sloman
> <bill....@ieee.org> wrote:
>
>> On Nov 27, 5:08 am, John Larkin
>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>> On Fri, 26 Nov 2010 03:26:11 -0800 (PST),BillSloman
>>>
>>>
>>>
>>> <bill.slo...@ieee.org> wrote:
>>>> On Nov 26, 9:26 am, Bitrex<bit...@de.lete.earthlink.net> wrote:
>>>>> I suppose I could set things up to do the research myself, but since I'm
>>>>> feeling lazy I thought I'd check first: By how much do you have to
>>>>> reverse bias the emitter-base junction of a common transistor such as
>>>>> the 2N2222 before it starts getting appreciably noisy? Does it have to
>>>>> be above the 5-6 volt breakdown voltage, or will significant noise occur
>>>>> before that point? I'm looking for a noise source that will work with a
>>>>> 3 volt supply. Maybe a different transistor with a lower breakdown voltage?
>>>
I'm a big fan of shot noise for this. By my actual measurement it's
Gaussian out beyond 7.1 sigma, corresponding to a threshold crossing
rate of 10**-11 times the bandwidth. Another key virtue is that the
noise PSD is derivable from the DC photocurrent by a trivial
first-principles calculation.
You do need a decent amplifier, and enough photocurrent to drop a volt
or two across your (metal film) sense resistor, but it's easy to get way
within 1 dB accuracy that way. Best of all, at least for electrooptics
folk like yours truly, the frequency response is *exactly* that of your
front end.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net
Phil Hobbs
> On Sat, 27 Nov 2010 18:11:00 -0500, Jamie
> <jamie_ka1lpa_not_v...@charter.net> wrote:
>
>> John Larkin wrote:
>>
>>>
>>>
>>> matter to different people. The RF boys want spectral flatness. Crypto
>>> people want zero predictability. Process people might want a nearly
>>> Gaussian PD. Audio folks don't want audible defects, like hum or
>>> popcorn noise or detected RF.
>>>
>>>
>>>> Noise is noise, be it white, pink, brown and your analogy "Popcorn",
>>>> first time I've heard that one ect !
>>>
>>>
>>>
>>> John
>>>
>> That's interesting, I did look that up, and it appears to be another
>> name of something I was already aware of.. I read a parcel on
>> Wki and it mention behavior of defects found in transistors.
>>
>> I did have a batch of smt 2222's that would not work in linear
>> applications, only switching because at a specific current (Ice) No
>> mater the configuration, I was getting a small noise that could be seen
>> via scope in the collector circuit. You go below or above this current
>> point and it would go away.. When I set the scope up to expand the view
>> on that section, I go what looked like a random oscillation.
>>
>> I used a spectrum analyzer on that point and got random noise that
>> started around 100hz up to about 1 mhz.. It would change just by varying
>> the bias slightly.
>>
>> I have since replaced that batch and all is well once again.
>>
>> MMBT2222 iirc...
>>
>>
>
> Popcorn noise is super low frequency and is usually seen in the form
> of discrete/bimodal level shifts, like the output of a random pulse
> generator. It's common for it to look like pulses, milliseconds in
> duration, milliseconds to seconds apart, or random in time level
> shifts. Sometimes a part will sit quietly for hours and then let out a
> burst. The magnitude is in the ballpark of 10s of microvolts RTI. The
> cause is supposedly ionic contamination in oxide layers or something.
> It's named because it sounds like corn popping.
>
> Analog Devices has an appnote where they claim it's a thing of the
> past. They should test some of their own DACs.
>
> John
>
A lot of 1/f noise is actually popcorn in character. With peace to AD,
it's getting worse rather than better as devices shrink--it's mostly
local conductance fluctuations.
Electromigration is another source of popcorn noise.
Phil Hobbs
I remember back in the day when you needed at least a business *name*,
not necessarily some bureaucratic registration , to order parts from
distributors in Canada--there was some regulation connected with sales
tax IIRC.
My late friend Brian Murray, a really amazing tech who taught me how to
tune fancy filters when I was but a stripling, called his imaginary firm
"EnemaTronics", and nobody blinked an eye. (Subtlety was never Brian's
thing--he came to my wedding in leathers. RIP.)
Cheers
Phil Hobbs
(Coming to you from the very pleasant Delta Sky Club in Salt Lake City,
on my way to Albuquerque NM.)