1.5V, 2-NPN White LED Driver Circuit (LTspice)
analog
This post presents an alternate, regulated version of a very simple
1.5V battery based white LED driver circuit from Electronic Design:
http://www.elecdesign.com/Files/29/5886/Figure_01.gif
The LTspice circuit file at the end of this post uses battery volt-
age feedforward and LED current feedback to reduce the effect of
operating conditions on average LED current. The following table
summarizes results of simulations under a range of input voltages.
Vin | Iout | Pout | eff
------+------+------+------
0.9v | 9ma | 34mw | .77
1.1v | 21ma | 94mw | .80
1.3v | 21ma | 92mw | .81
1.5v | 21ma | 87mw | .82
1.7v | 21ma | 84mw | .83
Notes about circuit operation:
Q2 turns off shortly after Q1 begins to steal base current due to
the rising saturation voltage on Q2 (coupled through R3 C1).
Since saturation voltage is device dependent, R1 may have to be
decreased (increased) for weaker (stronger) devices (Q2). A small
emitter degeneration resistor for Q2 could reduce this effect at
the cost of some efficiency and complexity.
Look for attached gifs of the schematic and waveforms in a follow-
up post in alt.binaries.schematics.electronic.
Download the full featured *free* LTspice circuit simulator at:
http://ltspice.linear.com/software/swcadiii.exe
The LTspice file follows directly (beware of unintended line wrap):
---- cut, paste and save as LED_driver.asc ----
Version 4
SHEET 1 1036 680
WIRE -160 416 -160 256
WIRE -160 192 -160 48
WIRE -160 48 -80 48
WIRE 288 48 288 144
WIRE 288 240 288 416
WIRE 0 416 0 352
WIRE 0 256 0 192
WIRE 0 80 0 48
WIRE 0 48 32 48
WIRE 0 416 -160 416
WIRE 144 208 144 176
WIRE 144 48 176 48
WIRE 112 48 144 48
WIRE 288 48 432 48
WIRE -160 416 -160 432
WIRE 432 48 432 160
WIRE 352 416 288 416
WIRE 352 384 352 416
WIRE 432 416 432 400
WIRE 256 304 320 304
WIRE 352 304 352 320
WIRE 432 416 352 416
WIRE 224 192 32 192
WIRE 0 192 0 160
WIRE 144 304 176 304
WIRE 144 304 144 272
WIRE 288 416 80 416
WIRE 64 304 80 304
WIRE 432 320 432 304
WIRE 432 304 352 304
WIRE 432 224 432 304
WIRE 80 304 80 320
WIRE 80 384 80 416
WIRE 80 416 0 416
WIRE 80 304 112 304
WIRE -32 48 0 48
WIRE 144 80 144 48
WIRE 176 48 288 48
WIRE 32 192 0 192
WIRE 112 304 144 304
WIRE 144 176 144 160
WIRE 320 304 352 304
WIRE -80 48 -80 176
WIRE -80 256 -80 304
WIRE -80 48 -32 48
WIRE -80 304 64 304
FLAG -160 432 0
FLAG -32 48 1
FLAG 176 48 2
FLAG 32 192 3
FLAG 112 304 4
FLAG 144 176 5
FLAG 320 304 6
SYMBOL npn 64 256 M0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL npn 224 144 R0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL res 272 288 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R4
SYMATTR Value 3k3
SYMBOL res -16 64 R0
SYMATTR InstName R2
SYMATTR Value 330
SYMBOL cap 128 208 R0
WINDOW 0 32 16 Left 0
WINDOW 3 32 48 Left 0
SYMATTR InstName C1
SYMATTR Value 1n
SYMBOL Misc\\cell -160 192 M0
WINDOW 123 0 0 Left 0
WINDOW 39 24 72 Left 0
WINDOW 3 24 44 Left 0
SYMATTR SpiceLine Rser=10m
SYMATTR InstName V1
SYMATTR Value 1.5
SYMBOL ind 16 64 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName L1
SYMATTR Value 100µ
SYMATTR SpiceLine Ipk=1 Rser=0.33 Rpar=0 Cpar=0 mfg="WE eiSos" pn="744 562 0"
SYMBOL diode 416 160 R0
WINDOW 0 40 16 Left 0
WINDOW 3 40 52 Left 0
SYMATTR InstName D2
SYMATTR Value LED
SYMBOL res 416 304 R0
SYMATTR InstName R5
SYMATTR Value 10
SYMBOL diode 64 384 M180
WINDOW 0 40 48 Left 0
WINDOW 3 40 12 Left 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL res 128 64 R0
SYMATTR InstName R3
SYMATTR Value 330
SYMBOL polcap 336 320 R0
WINDOW 0 32 16 Left 0
WINDOW 3 32 52 Left 0
SYMATTR InstName C2
SYMATTR Value 10µ
SYMATTR SpiceLine V=50 Irms=170m Rser=1 MTBF=5000 Lser=0 mfg="Nichicon" pn="UPG1H100MPH" type="Al electrolytic" ppPkg=1
SYMBOL res -96 160 R0
SYMATTR InstName R1
SYMATTR Value 4k3
TEXT 432 8 Center 0 !.model LED d(Vfwd=3.4V Ron=10)
TEXT -298 10 Left 0 !.tran 0 .3m .1u uic
TEXT 528 120 Left 0 ;R1: 4k3 R4: 3k3\n+Vin Iout Pout eff\n_0.9v 9ma 34mw .77\n1.1v 21ma 94mw .80\n1.3v 21ma 92mw .81\n1.5v 21ma 87mw .82\n1.7v 21ma 84mw .83
Andre
> This post presents an alternate, regulated version of a very simple
> 1.5V battery based white LED driver circuit from Electronic Design:
Interesting. I found a way to enhance the efficiency of a similar
circuit using nothing more than a single silicon diode from base to
emitter on the output transistor.
(this is the "mirror" circuit that uses an NPN and PNP transistor, and
about two other parts).
Henry Kolesnik
tnx
hank wd5jfr
"Andre" <test...@yahoo.com> wrote in message
news:2c2cf14c.04010...@posting.google.com...
Tim Williams
news:eummvvsu4o2hjr5ak...@4ax.com...
> Dear Henry,
>
> It is seldom necessary to quote an entire message that quotes another
> entire message simply to add "post your circuit".
Dear James,
It is seldom necessary to quote an entire message that quotes another entire
message that quotes another entire message simply to add three lines of text
at the bottom.
Trim or top post.
Tim
--
"That's for the courts to decide." - Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms
Tim Williams
Tim
--
"That's for the courts to decide." - Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms
"James Meyer" <jme...@nowhere.com> wrote in message
news:c3nmvv4qi874b12qh...@4ax.com...
> On 6 Jan 2004 06:27:55 -0800, test...@yahoo.com (Andre) wroth:
Tim Auton
>Where's your post? I scrolled down five pages before giving up.
Five pages of what? I stopped at your (broken) sig separator. It's
"-- " not "--". Snip and quote properly if you want to be a usenet
cop.
Tim, just waiting for a speling, grammar or formatting flame.
--
The .sig is dead.
Mark Jones
this bit-@connect-2.co.uk R.Lewis
Bill Garber
"R.Lewis" <h.lewis-not this bi...@connect-2.co.uk> wrote in
message news:bthkol$ena$1...@thorium.cix.co.uk...
: Why do you have to click on 'Start' when you want to stop
Windows?
That's for the people who use AOL. ;-)
Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4...@comXcast.net
Remove - SPAM and X to contact me
---
This email ain't infected, dude!
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.556 / Virus Database: 348 - Release Date: 12/26/03
John Woodgate
wrote (in <bthkol$ena$1...@thorium.cix.co.uk>) about '1.5V, 2-NPN White LED
Driver Circuit (LTspice)', on Wed, 7 Jan 2004:
>Why do you have to click on 'Start' when you want to stop Windows?
>
>
blue screen. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
Al
"Bill Garber" <will...@comcast.net> wrote:
> "R.Lewis" <h.lewis-not this bi...@connect-2.co.uk> wrote in
> message news:bthkol$ena$1...@thorium.cix.co.uk...
> : Why do you have to click on 'Start' when you want to stop
> Windows?
>
> That's for the people who use AOL. ;-)
>
That's nothin' I have to push "NO" on my cell phone to turn it on. I
guess it's "ON" backwards.
Al
--
There's never enough time to do it right the first time.......
Tim Williams
news:bthkol$ena$1...@thorium.cix.co.uk...
I don't. I ALT+F4 :o
petrus bitbyter
"R.Lewis" <h.lewis-not this bi...@connect-2.co.uk> schreef in bericht
news:bthkol$ena$1...@thorium.cix.co.uk...
> Why do you have to click on 'Start' when you want to stop Windows?
>
>
I heard a lot of rumours about it. I remember only two of them:
- Windows is so great an operating system that nowbody ever wants to stop
it.
- The developers simply forgot the stop button as they never needed it.
If anyone knows better, I like to hear it. Always in the mood of learning
something new.
petrus
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.554 / Virus Database: 346 - Release Date: 21-12-2003
Bill Garber
"petrus bitbyter" <p.k...@hccnet.nl> wrote in message
news:zf2Lb.106910$g%5.8...@amsnews02.chello.com...
:
: "R.Lewis" <h.lewis-not this bi...@connect-2.co.uk> schreef in
bericht
: news:bthkol$ena$1...@thorium.cix.co.uk...
: > Why do you have to click on 'Start' when you want to stop
Windows?
:
: I heard a lot of rumours about it. I remember only two of them:
:
: - Windows is so great an operating system that nowbody ever
wants to stop
: it.
:
: - The developers simply forgot the stop button as they never
needed it.
:
: If anyone knows better, I like to hear it. Always in the mood
of learning
: something new.
:
: petrus
I can't quote this, but I read somewhere that Bill Gates
himself had told a group that you press START to initiate
any function, and since SHUT DOWN is a function..........
Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4...@comXcast.net
Remove - SPAM and X to contact me
---
This email ain't infected, dude!
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.559 / Virus Database: 351 - Release Date: 1/8/04
Bill Garber
"John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in message
news:a0C2UdAwcG$$Ew...@jmwa.demon.co.uk...
: I read in sci.electronics.design that R.Lewis
<h.lew...@this.bit->
: wrote (in <bthkol$ena$1...@thorium.cix.co.uk>) about '1.5V, 2-NPN
White LED
: Driver Circuit (LTspice)', on Wed, 7 Jan 2004:
: >Why do you have to click on 'Start' when you want to stop
Windows?
: >
: >
: You don't. Wait a few minutes and it will stop by itself, with
a pretty
: blue screen. (;-)
Mine is Maroon now. Get a program called BSOD.EXE
when you are sick of the Blue, change it to whatever
suits you. ;-)
Michael A. Terrell
>
> "John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in message
> news:a0C2UdAwcG$$Ew...@jmwa.demon.co.uk...
> : I read in sci.electronics.design that R.Lewis
> <h.lew...@this.bit->
> : wrote (in <bthkol$ena$1...@thorium.cix.co.uk>) about '1.5V, 2-NPN
> White LED
> : Driver Circuit (LTspice)', on Wed, 7 Jan 2004:
> : >Why do you have to click on 'Start' when you want to stop
> Windows?
> : >
> : >
> : You don't. Wait a few minutes and it will stop by itself, with
> a pretty
> : blue screen. (;-)
>
> Mine is Maroon now. Get a program called BSOD.EXE
> when you are sick of the Blue, change it to whatever
> suits you. ;-)
>
> Bill
My last computer was set for a blood red screen. I think I used
Tweek-UI to change it.
Also, a Monty Python character yelled, "You started it, you bleeding
pig!" when you closed Windows on my last machine that ran Win 3.11.
--
We now return you to our normally scheduled programming.
Take a look at this little cutie! ;-)
http://home.earthlink.net/~mike.terrell/photos.html
Michael A. Terrell
Central Florida
Bill Garber
"Michael A. Terrell" <mike.t...@earthlink.net> wrote in
message news:3FFD85BA...@earthlink.net...
: Bill Garber wrote:
: >
: > "John Woodgate" <j...@jmwa.demon.contraspam.yuk> wrote in
message
: > news:a0C2UdAwcG$$Ew...@jmwa.demon.co.uk...
: > : I read in sci.electronics.design that R.Lewis
: > <h.lew...@this.bit->
: > : wrote (in <bthkol$ena$1...@thorium.cix.co.uk>) about '1.5V,
2-NPN
: > White LED
: > : Driver Circuit (LTspice)', on Wed, 7 Jan 2004:
: > : >Why do you have to click on 'Start' when you want to stop
: > Windows?
: > : >
: > : You don't. Wait a few minutes and it will stop by itself,
with
: > a pretty
: > : blue screen. (;-)
: >
: > Mine is Maroon now. Get a program called BSOD.EXE
: > when you are sick of the Blue, change it to whatever
: > suits you. ;-)
: >
: > Bill
:
: My last computer was set for a blood red screen. I think I
used
: Tweek-UI to change it.
Yeah, that works too. I don't particularly
like Tweaking programs. Some of them tend to
change things in an undesirable way.
: Also, a Monty Python character yelled, "You started it, you
bleeding
: pig!" when you closed Windows on my last machine that ran Win
3.11.
I had a startling startup sound so I would
know when my kids were on it from the other
room. ;-) They didn't like it though.
this bit-@connect-2.co.uk R.Lewis
"Bill Garber" <will...@comcast.net> wrote in message
news:XMGdnRDKXZu...@comcast.com...
>
> "petrus bitbyter" <p.k...@hccnet.nl> wrote in message
> news:zf2Lb.106910$g%5.8...@amsnews02.chello.com...
> :
> : "R.Lewis" <h.lewis-not this bi...@connect-2.co.uk> schreef in
> bericht
> : news:bthkol$ena$1...@thorium.cix.co.uk...
> : > Why do you have to click on 'Start' when you want to stop
> Windows?
> :
> : I heard a lot of rumours about it. I remember only two of them:
> :
> : - Windows is so great an operating system that nowbody ever
> wants to stop
> : it.
> :
> : - The developers simply forgot the stop button as they never
> needed it.
> :
> : If anyone knows better, I like to hear it. Always in the mood
> of learning
> : something new.
> :
> : petrus
>
> I can't quote this, but I read somewhere that Bill Gates
> himself had told a group that you press START to initiate
> any function, and since SHUT DOWN is a function..........
>
> Bill @ GarberStreet Enterprizez };-)
Ah - now I see
(as the blind man said as he fell down a hole)
Louis Bybee
> news:zf2Lb.106910$g%5.8...@amsnews02.chello.com...
> :
> : "R.Lewis" <h.lewis-not this bi...@connect-2.co.uk> schreef in
> bericht
> : news:bthkol$ena$1...@thorium.cix.co.uk...
> : > Why do you have to click on 'Start' when you want to stop
> Windows?
> :
> : I heard a lot of rumours about it. I remember only two of them:
> :
> : - Windows is so great an operating system that nowbody ever
> wants to stop
> : it.
> :
> : - The developers simply forgot the stop button as they never
> needed it.
> :
> : If anyone knows better, I like to hear it. Always in the mood
> of learning
> : something new.
> :
> : petrus
>
I can't believe with the high number of intelligent people frequenting these
groups that you all missed the obvious!
Bill & Co. didn't have to include a stop button as it would have duplicated
a feature already existing in the software!
The OS was designed to crash, or lock up often enough that it was likely
that one such occurance would coincide with your desire to stop using the
computer. :-]
Louis--
*********************************************
Remove the two fish in address to respond
james
> 1.5V battery based white LED driver circuit from Electronic Design:
>
> http://www.elecdesign.com/Files/29/5886/Figure_01.gif
>
<snip>
I've built this circuit and the one that analog posted as a LTSpice
file and they both work quite well. Is there any way to improve the
low voltage performance?
Obviously you are limited by the VBE of the bipolar transistors - can
you get low Vbe transistors?
James
John Woodgate
wrote (in <16a7c3ae.04010...@posting.google.com>) about
'1.5V, 2-NPN White LED Driver Circuit (LTspice)', on Fri, 9 Jan 2004:
>Obviously you are limited by the VBE of the bipolar transistors - can
>you get low Vbe transistors?
For simple, room temperature applications for personal use, it is not
unreasonable to use germanium transistors (Vbe = 0.2 to 0.3 V), and some
types are still available.
Mark Jones
> I read in sci.electronics.design that james <thedat...@yahoo.com>
> wrote (in <16a7c3ae.04010...@posting.google.com>) about
> '1.5V, 2-NPN White LED Driver Circuit (LTspice)', on Fri, 9 Jan 2004:
>
>> Obviously you are limited by the VBE of the bipolar transistors - can
>> you get low Vbe transistors?
>
> For simple, room temperature applications for personal use, it is not
> unreasonable to use germanium transistors (Vbe = 0.2 to 0.3 V), and some
> types are still available.
Aaah, but can they switch any appreciable current?
John Woodgate
(in <6NednXSrft-...@buckeye-express.com>) about '1.5V, 2-NPN
White LED Driver Circuit (LTspice)', on Fri, 9 Jan 2004:
>In news:FPukV0BTet$$Ew...@jmwa.demon.co.uk (John Woodgate):
>> I read in sci.electronics.design that james <thedat...@yahoo.com>
>> wrote (in <16a7c3ae.04010...@posting.google.com>) about
>> '1.5V, 2-NPN White LED Driver Circuit (LTspice)', on Fri, 9 Jan 2004:
>>
>>> Obviously you are limited by the VBE of the bipolar transistors - can
>>> you get low Vbe transistors?
>>
>> For simple, room temperature applications for personal use, it is not
>> unreasonable to use germanium transistors (Vbe = 0.2 to 0.3 V), and some
>> types are still available.
>
>
> Aaah, but can they switch any appreciable current?
>
some devices rated at 20 A at least, but they probably aren't available
any more. Of course, they were slow. Typical fbeta of 3 kHz, IIRC.
Watson A.Name - Watt Sun, Dark Remover
thedat...@yahoo.com mentioned...
> analog <ana...@ieee.org> wrote in message news:<3FFA6862...@ieee.org>...
> > This post presents an alternate, regulated version of a very simple
> > 1.5V battery based white LED driver circuit from Electronic Design:
> >
> > http://www.elecdesign.com/Files/29/5886/Figure_01.gif
> >
>
> <snip>
>
> I've built this circuit and the one that analog posted as a LTSpice
> file and they both work quite well. Is there any way to improve the
> low voltage performance?
I built this circuit in the above URL and it is the only one I've
managed to get to work below .7VDC, and in fact puts out a little even
at .58 VDC. That's really quite low!
The other one that was posted here, which has the 10 ohm resistor in
series with the LED's cathode lead to sense the current, is very
snotty. It sometimes fails to come on when powered on, and then draws
200 mA excessive current when it's not oscillating.
> Obviously you are limited by the VBE of the bipolar transistors - can
> you get low Vbe transistors?
Silicon transistors always have .6Vbe. You can use germanium which
have about .2 Vbe, but they tend to be lower current and power than
silicon. The circuit in this URL gets around this by using a starter
circuit with a JFET.
http://www.ece.uvic.ca/~jbornema/Journals/064a-97ia-jmd.pdf
> James
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
Watson A.Name - Watt Sun, Dark Remover
<127.0.0.1> mentioned...
Ummm... How about 50 amps? Motorola's 2N2728 germanium power
transistor was made specifically for power converters operating at low
voltages. However its Vceo is only 5V.
We used to make 100 watt 12VDC to 120VAC inverters from a pair of
2N457A germanium power transistors. You can still find germanium
power transistors around. I think I saw some on Ebay.
Watson A.Name - Watt Sun, Dark Remover
j...@jmwa.demon.contraspam.yuk mentioned...
> I read in sci.electronics.design that Mark Jones <127.0.0.1@?.?> wrote
> (in <6NednXSrft-...@buckeye-express.com>) about '1.5V, 2-NPN
> White LED Driver Circuit (LTspice)', on Fri, 9 Jan 2004:
> >In news:FPukV0BTet$$Ew...@jmwa.demon.co.uk (John Woodgate):
> >> I read in sci.electronics.design that james <thedat...@yahoo.com>
> >> wrote (in <16a7c3ae.04010...@posting.google.com>) about
> >> '1.5V, 2-NPN White LED Driver Circuit (LTspice)', on Fri, 9 Jan 2004:
> >>
> >>> Obviously you are limited by the VBE of the bipolar transistors - can
> >>> you get low Vbe transistors?
> >>
> >> For simple, room temperature applications for personal use, it is not
> >> unreasonable to use germanium transistors (Vbe = 0.2 to 0.3 V), and some
> >> types are still available.
> >
> >
> > Aaah, but can they switch any appreciable current?
> >
> It depends on which devices are still available, of course. There were
> some devices rated at 20 A at least, but they probably aren't available
> any more. Of course, they were slow. Typical fbeta of 3 kHz, IIRC.
I see power transistors on Ebay. Like
http://search.ebay.com/search/search.dll?cgiurl=http%3A%2F%2Fcgi.ebay.
com%2Fws%2F&MfcISAPICommand=GetResult&ht=1&from=R7&ebaytag1=ebayreg&qu
ery=germanium+power&query2=germanium+power&search_option=1&exclude=&ca
tegory0=&minPrice=&maxPrice=&ebaytag1code=0&st=&SortProperty=MetaEndSo
rt
Or if that's too much, just do a search and type in germanium power.
But I fail to see why anyone would want those weird Russian power
transistors. :-P
Go to www.nteinc.com and get the data sheet for the replacement for
2N457A, which is the NTE104, good for a hundred watts. It's a bit on
the expensive side, see mouser's listing for it.
http://www.mouser.com/index.cfm?&handler=search.listcategory&Ntt=*NTE1
04*&terms=NTE104&Dk=1&D=*NTE104*&N=0&crc=true
John Woodgate
Remover <alond...@hotmail.com> wrote (in <MPG.1a6a0699eea2f335989b23@n
ews.dslextreme.com>) about '1.5V, 2-NPN White LED Driver Circuit
(LTspice)', on Sat, 10 Jan 2004:
>Ummm... How about 50 amps? Motorola's 2N2728 germanium power
>transistor was made specifically for power converters operating at low
>voltages. However its Vceo is only 5V.
ft = 1 Hz? (;-) I remember the ADZ11 and 12, which had fbeta about 3 kHz
and not much beta.
Watson A.Name - Watt Sun, Dark Remover
j...@jmwa.demon.contraspam.yuk mentioned...
> I read in sci.electronics.design that Watson A. Name - Watt Sun, Dark
> Remover <alond...@hotmail.com> wrote (in <MPG.1a6a0699eea2f335989b23@n
> ews.dslextreme.com>) about '1.5V, 2-NPN White LED Driver Circuit
> (LTspice)', on Sat, 10 Jan 2004:
>
> >Ummm... How about 50 amps? Motorola's 2N2728 germanium power
> >transistor was made specifically for power converters operating at low
> >voltages. However its Vceo is only 5V.
>
> ft = 1 Hz? (;-) I remember the ADZ11 and 12, which had fbeta about 3 kHz
> and not much beta.
I went over to Fry's this afternoon to pick up a spray can of some
DeoxIT (see other thread), and I checked the price of the NTE104.
Mouser lists it for $16, and Fry's has it marked as $9.99. It has a
Ft of 10 kHz.
I used a Deltakit Mark 10 CD ignition system for many years on my van,
and it used two germanium power transistors for the inverter, both
were mounted directly to the heatsink and case because the collectors
were at ground. I had no thermal problems with them, even tho the CDI
was in the engine compartment.
analog
I think I remember that someone posted that they actually built this
circuit and it worked but had some problems at low voltage.
Unfortunately, now that I have a little time to respond to that post,
I can't seem to find it (perhaps it has expired from my newsserver).
If the original poster hasn't expired as well could he or she please
repost that message.
Thank you.
Michael
(snip)
> and it used two germanium power transistors for the inverter, both
> were mounted directly to the heatsink and case because the collectors
> were at ground. I had no thermal problems with them, even tho the CDI
> was in the engine compartment.
>
Ahhh yes ... the venerable Delta CDI. A couple friends had those. That
was back in the days of disco, helmet hair, wallpaper shirts, flaired
doubleknit pants, platform shoes .....
I opted for the Heathkit CDI for my '71 Pinto. That was a goodie too.