[fun] Weird electronic circuits collection

[Piotr Wyderski]

Hello,

just out of curiosity, could youl please name the weirdest
practical components abuses/entering the non-linear region/
unusual, non-obvious, but still legitimate applications you know of?
I think it is fun to learn about them, here is my list:

1. Saturable reactors and all that spawns from them.
2. Parametric resonance-based magnetic digital circuits. (google =>
parametron)
3. Negistor oscillator.
4. Single-transistor photovoltaic (rly?) negative voltage generator.
5. Transformerless valve audio amplifiers.
6. Dynatron oscillator.
7. Voltage regulator valves used as Geiger counters.

Best regards, Piotr

[tabb...@gmail.com]

VDF as valve in various apps. It does depend what you mean by legitimate.


NT

[pcdh...@gmail.com]

Resetting an op amp integrator by inverting the power supplies. (Turns the ESD diodes into a bridge.)

Dimly illuminated LEDs as subpicoamp switches with controllable bias current (as used in Footprints).

Inverted BJT switches.

Pease's voltage inverter (zener the BE junction and C goes below E)

Williams-tube (CRT) memory

Cheers

Phil Hobbs

[whit3rd]

On Thursday, December 7, 2017 at 9:52:03 AM UTC-8, Piotr Wyderski wrote:

> just out of curiosity, could youl please name the weirdest
> practical components abuses/entering the non-linear region/
> unusual, non-obvious, but still legitimate applications you know of?

A common sensor for liquid nitrogen levels, is a carbon resistor.
Resistance of carbon (a semimetal) goes up sharply when it
gets cold.

Wiegand wire; a magnetic core that toggles between
two permanent-magnet polarities, is a B field sensor element
that generates accurate repeatable pulses.

Microwave oven: an odd use for oscillator vacuum tubes.

[Lasse Langwadt Christensen]

universal remote using the transmit LED as light sensor for recording ir

[George Herold]

Reverse biased GaAs LED as Spad. (single photon avalanche detector.)
http://nebula.wsimg.com/0b846f1e91ab9c7442a61c8c35680a51?AccessKeyId=027C3581808C75E81679&disposition=0&alloworigin=1

Very inefficient, but fun.

It started on SEB when someone questioned the V_rev. max of all leds
as 5V.

George H.

[John Larkin]

Cheap rectifier diodes used as kilovolt:nanosecond pulse generators.

PHEMTs used as diodes

PHEMTs used as switches (they are generally characterized as linear RF
things)

Transistors used as reference zeners

LVDS receivers used as comparators

PV optocouplers used as floating power supplies, sort of what you
mentioned.

Mosfets used as heaters

Surface-mount resistors ditto

PCB traces ditto

CRTs used as signal processors

PMTs as noise generators (like radar jammers)

Vacuum tubes as vacuum gages

Capacitors used as power amps

Capacitors used as varicaps

Varicaps used as opamp front ends

Capacitors used as temperature sensors

Neon bulbs used as xray detectors

Mosfets ditto

DRAMS used as imagers

EPROMS as xray detectors

FR4 used as a thermometer

Water used as a resistor







--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

[bitrex]

Korg MS-20 voltage-controlled filter, using reverse-biased BJTs as the
variable resistance element:

<http://www.aleph.co.jp/~takeda/radio/img/MS20Clone2.gif>

Soviet Polivoks voltage-controlled filter, adjust cutoff frequency by
current-controlling op-amp GBW:

<http://m.bareille.free.fr/modular1/vcf_polivoks/vcf_polivoks_sh0.gif>

Use a bridge rectifier as a variable resistance:

<https://www.google.com/patents/US4039980?dq=yasuo+nagahama&hl=en&sa=X&ei=ZMsnVc3QCMvFsAWsxIHwBA&ved=0CFUQ6AEwCA>

Page 11 of this app note where an entire McIntosh 75 tube power
amplifier is used as a schematic component for an isolated high voltage
op-amp power booster:

<http://www.ti.com/lit/an/snoa600b/snoa600b.pdf>

High voltage regulator using an LM317 and pass tube with the LM317
connected between the tube's cathode and grid:

<https://www.tubecad.com/2008/11/16/lm317%20hv%20reg.png>

Build an audio power amp out of voltage regulators:

<http://www.electroschematics.com/wp-content/uploads/2012/06/1watt-7905-stereo-amplifier.jpg>


You can make a LDO out of a TL431 and a couple other parts. You can make
a MFB filter out of a TL431. You can use two TL431 to make a high-gain
differential amplifier. You can make just about anything out of a TL431

[Joerg]

Making smoke :-)

https://www.youtube.com/watch?v=rAB5AfpOd_0

--
Regards, Joerg

http://www.analogconsultants.com/

[Joerg]

On 2017-12-07 12:29, bitrex wrote:

[...]

> Build an audio power amp out of voltage regulators:
>
> <http://www.electroschematics.com/wp-content/uploads/2012/06/1watt-7905-stereo-amplifier.jpg>
>

I built a 1kW+ RF amp from five color TV horizontal flyback tubes
because they were formally rated at 30W plate dissipation. That way we
got around the 150W plate dissipation limit. Many ham radio operators in
Germany did that.

Years later they closed this loophole and legislated 750W max RF output.
Not sure if older amps are grandfathered but knowing Germany they
probably aren't.

This is the amp:

http://www.analogconsultants.com/ng/images/PL509amp2.jpg

Below is the "post-loophole" amp I built, throttled to 750W but it could
send that into an almost dead short if needed:

http://www.analogconsultants.com/ng/images/QB5amp2.jpg

[...]

[whit3rd]

Contact wear (as in relay points) maximized
and named 'electrical discharge machining'.

Mercury-in-vinegar with an iron nail, the 'Beating Heart'
oscillator. <https://youtu.be/m6631u7d4E0>

Battery powered, Oxford bell <https://youtu.be/UtQGYz4f3YQ>
... which is uneconomic (no repeat battery sales)

[bitrex]

Wasn't there some European country that in the early days of radio taxed
receivers on the number of tubes they had, so some clever company had a
custom tube built that contained all the plates, grids, and cathodes
required to make a suphert, inside a single envelope? LOL

[Joerg]

Never heard of that one but I could imagine their tax guys pulling such
a stunt. I still have grandpa's radio which has such a tube. It can be
called the first integrated circuit because there are also resistors and
caps in it:

http://lampes-et-tubes.info/rt/rt175.php?l=f

Some European countries used to set property taxes according to the
number of windows so frugal people bricked up a few windows to save on
taxes.

[Chris Jones]

Using the current limit and thermal limit of (many) 7805 regulators as a
temperature controlled heater for diesel injection pumps running on
straight vegetable oil:
http://www.trappertricks.de/eheizung/
(not my idea, but I thought it was quite clever)

[Piotr Wyderski]

Lasse Langwadt Christensen wrote:

> universal remote using the transmit LED as light sensor for recording ir

Same in many of the closet lighting systems, the LEDs are used as door
opening sensors for a moment.

Best regards, Piotr

[Piotr Wyderski]

John Larkin wrote:

> LVDS receivers used as comparators

BTDT.

> PV optocouplers used as floating power supplies, sort of what you
> mentioned.

I have never used it in practice (so far), learnt about it from you.

> Mosfets used as heaters

BJTs ditto. CA3046 used as a heater, sensor and active ovenized element
of something temperature-sensitive.

> PCB traces ditto

Common way to heat the mirrors in buses.

> CRTs used as signal processors

As storage elements -- yes, but processsing?

> Capacitors used as power amps

How? Electrostatic amplifiers based on saturable dielectrics? (another
item to be added to the list).

+arc oscillators

> Capacitors used as varicaps

Another idea I learnt from you, could be very potent.

> Varicaps used as opamp front ends

What for?

Best regards, Piotr

[Piotr Wyderski]

tabb...@gmail.com wrote:

> VDF as valve in various apps.

Why?

> It does depend what you mean by legitimate.

As strange a circuit as you wish, but without irreversible
violation of its SOAR. BC107 used for switching kiloamperes
wouldn't count. ;-)

Best regards, Piotr

[Tom Gardner]

On 07/12/17 22:10, Joerg wrote:
> Some European countries used to set property taxes according to the number of
> windows so frugal people bricked up a few windows to save on taxes.

And in the UK, many remain bricked up 1.5 centuries after
the tax disappeared. (The tax itself also lasted 1.5 centuries)

[Dave Platt]

In article <f8tsj1...@mid.individual.net>,

Joerg <ne...@analogconsultants.com> wrote:

>> Wasn't there some European country that in the early days of radio taxed
>> receivers on the number of tubes they had, so some clever company had a
>> custom tube built that contained all the plates, grids, and cathodes
>> required to make a suphert, inside a single envelope? LOL
>
>
>Never heard of that one but I could imagine their tax guys pulling such
>a stunt. I still have grandpa's radio which has such a tube. It can be
>called the first integrated circuit because there are also resistors and
>caps in it:

If you dig through the old radio-design literature you'll find all
sorts of interesting designs.

There are some in which the incoming signal flows through the same
tube elements twice: e.g. it's both an RF amplifier and an audio
amplifier. There's a separate detector stage with a high-pass on its
input and a low-pass on its output.

There are other radios (quite a few) which share significant parts of
the circuitry between the AM and FM RF/IF paths. In some cases, a
triode or pentode which serves one role for AM reception, serves a
completely different role for FM reception.

And, yeah, tubes with two different sets and types of elements (e.g. a
pentode on one side and a triode on the other) were quite common.

I don't recall ever hearing of one which rolled up "magic eye"
tuning-indicator functionality with a more functional active section
such as a pentode, but it wouldn't surprise me much if at least one
such existed.

[Piotr Wyderski]

pcdh...@gmail.com wrote:

> Resetting an op amp integrator by inverting the power supplies. (Turns the ESD diodes into a bridge.)

Powering and clocking an MCU at the same time by connecting a coil to
its XTAL_IN pin and some other pin and using the ESD diodes as an RF
bridge rectifier.

Best regards, Piotr

[Michael A Terrell]

Dave Platt wrote:
>
> If you dig through the old radio-design literature you'll find all
> sorts of interesting designs.
>
> There are some in which the incoming signal flows through the same
> tube elements twice: e.g. it's both an RF amplifier and an audio
> amplifier. There's a separate detector stage with a high-pass on its
> input and a low-pass on its output.

That was called a Reflex radio.

[Chris Jones]

Didn't Vyvyan throw the toilet out the window in the young ones, to
avoid the toilet tax? I read that the toilet tax is being / has just
been reintroduced in some form.

[tabb...@gmail.com]

On Thursday, 7 December 2017 20:12:28 UTC, John Larkin wrote:

> CRTs used as signal processors

> Capacitors used as power amps

> Varicaps used as opamp front ends

how do you do those 3?

> FR4 used as a thermometer

Terrible capacitance tempco, but is it worth the additional circuitry you need to turn that into a temperature signal?


NT

[Joerg]

There are also FET stages that work in both directions in transceivers.
I think the Atlas 210 and 215 series are among them. I've got one that
still needs repair.

[Tom Gardner]

Ah yes. That was the best evocation of student life in the 70s :)
Given one of the houses my daughter lived in, I'm not sure it has
changed too much. Three examples:
- a hole appeared in the kitchen floor (not a trapdoor like
in my kitchen floor)
- the boiler failed, but one shower continued to have hot water;
apparently it was fed from next door!
- there was a problem with the electrical distribution where it
entered the house. The electricity companies refused to touch
the equipment because it was too old and couldn't be isolated

[pcdh...@gmail.com]

The superregen.

That trick of putting current boosters controlled by resistors in series with the supply pins of an op amp.

Avalanche transistors.

SCR inverters

Magnetic parametric dividers for generating 20-Hz telephone ring tones from 60 Hz

Cheers

Phil Hobbs

[bitrex]

I sketched out an idea for a one tube regenerative reflex radio a while
back but haven't had a chance to build it yet. I should do that before
the end of the winter to take advantage of the good SW listening season

[Joerg]

They have weird wiring in the UK. As a student I stayed in a cheap
London hotel. You had to insert a coin into a box at the end of a long
hallway for a few minutes of hot shower water, then run as fast as you
can to the _other_ end where the shower was. Tick-tock-tick-tock, every
second counted. The timing was a bit erratic and occasionally it blitzed
off mid-stream. Ice cold water shot out. YOUWEEE! Then you had to insert
another coin. However, now you were naked and soaped up, plus there were
10 or more doors to hotel rooms along that hallway ...

[John Larkin]

On Thu, 7 Dec 2017 23:54:59 +0100, Piotr Wyderski
<pete...@neverland.mil> wrote:

>John Larkin wrote:
>
>> LVDS receivers used as comparators
>
>BTDT.
>
>> PV optocouplers used as floating power supplies, sort of what you
>> mentioned.
>
>I have never used it in practice (so far), learnt about it from you.
>
>> Mosfets used as heaters
>
>BJTs ditto. CA3046 used as a heater, sensor and active ovenized element
>of something temperature-sensitive.
>
>> PCB traces ditto
>
>Common way to heat the mirrors in buses.
>
>> CRTs used as signal processors
>
>As storage elements -- yes, but processsing?

I made it to the National Science Fair with my project "The
Cathode-Ray Tube as an Active Circuit Element". The idea was to sweep
the electron beam in a circle and sweep a mask, optical or
electrostatic pickup, and get a signal.

Bell Labs made a CRT ADC for early digital phone systems. An electron
sheet was deflected by the audio, and hit a grey-coded mask. 8 bit
companding!

Remember flying-spot scanners?

>
>> Capacitors used as power amps
>
>How? Electrostatic amplifiers based on saturable dielectrics? (another
>item to be added to the list).

Hi-K dielectrics vary C radically with voltage. So a low-power DC bias
can modulate a big AC signal.

>
>+arc oscillators

Some triggered spark gaps were awesome, kilovolts in picoseconds.
Early lidars used spark gaps and PMTs, to measure cloud heights and
such.

>
>> Capacitors used as varicaps
>
>Another idea I learnt from you, could be very potent.
>
>> Varicaps used as opamp front ends
>
>What for?

Some early Philbrick (discrete, potted) opamps and one TI amp
(monolithic) used a varactor bridge as the front end. It was AC
modulated, and the AC bridge imbalance signal was amplified and
synchronously detected. Nothing else was as good, for a while.


How about color TV HV rectifier tubes as xray sources?

"Foxhole radios" used a rusty razor blade as the detector. They may
have been tunnel diodes. Razor blades used to rust.

[Tim Williams]

"Piotr Wyderski" <pete...@neverland.mil> wrote in message
news:p0cgs2$g9r$1...@node2.news.atman.pl...

>> CRTs used as signal processors
>
> As storage elements -- yes, but processsing?

Yup, they put a perforated metal plate in there instead of a phosphor
screen; perforations just happened to correspond to binary codes. Apply
deflection, you've got an ADC!

More involved tricks, I'm not sure, but that's a good example.

>> Capacitors used as power amps
>
> How? Electrostatic amplifiers based on saturable dielectrics? (another
> item to be added to the list).

Parametric amplifier, I assume.

>> Varicaps used as opamp front ends
>
> What for?

IIRC, there was an HP electrometer that did this. Varicaps have low
leakage, thus, parametric op-amp with much lower input bias current than
other methods.

There's a lot of "measure thing with completely different property" in
physical instruments, like atomic structure by resonant frequency (AFM), or
gravity waves by interferometery (or every other damned thing with
interferometry, because it's so good). It seems odd to apply the same
principle with electronics (as you're starting and ending with electronic
signals), but sure, why not? :)

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/

[John Larkin]

Just make an LC or schmitt oscillator where a bit of the PCB is the
capacitor. It's ideal for compensating FR4 problems elsewhere on the
same board. An FR4 PCB cap has a tempco around -900 PPM/K.

[John Larkin]

On Thu, 7 Dec 2017 11:16:58 -0800 (PST), whit3rd <whi...@gmail.com>
wrote:

>On Thursday, December 7, 2017 at 9:52:03 AM UTC-8, Piotr Wyderski wrote:
>
>> just out of curiosity, could youl please name the weirdest
>> practical components abuses/entering the non-linear region/
>> unusual, non-obvious, but still legitimate applications you know of?
>

>A common sensor for liquid nitrogen levels, is a carbon resistor.
>Resistance of carbon (a semimetal) goes up sharply when it
>gets cold.

Silicon diodes are used as temperature sensors at liquid helium temps.
Below 20K, the tempco gets extreme.

One liquid helium level sensor is a vertical piece of wire in a tube.
Apply current and it gets superconductive in the liquid and resistive
in gas; measure the voltage.

>
>Wiegand wire; a magnetic core that toggles between
>two permanent-magnet polarities, is a B field sensor element
>that generates accurate repeatable pulses.

Core memory is actually pretty weird.

>
>Microwave oven: an odd use for oscillator vacuum tubes.

[pcdh...@gmail.com]

>>> Varicaps used as opamp front ends
>>
>> What for?

>IIRC, there was an HP electrometer that did this.  Varicaps have low
>leakage, thus, parametric op-amp with much lower input bias current than
>other methods.

The most famous is the Philbrick P2. Pease wrote an article or two on it.

Cheers

Phil Hobbs

[John Larkin]

Shock lines, NLTLs, are cool; a transmission line with nonlinear
elements. A voltage step gets faster as it propagates down the line.
It has been done with varactor diodes, hi-K capacitors (discrete and
continuous strips) and with saturating magnetics.

[George Herold]

Was one of those written about by B. Pease in one of J. Williams
Analog Circuit anthologies?

George H.

[George Herold]

On Thursday, December 7, 2017 at 7:02:31 PM UTC-5, John Larkin wrote:
> On Thu, 7 Dec 2017 15:32:58 -0800 (PST), tabb...@gmail.com wrote:
>
> >On Thursday, 7 December 2017 20:12:28 UTC, John Larkin wrote:
> >
> >> CRTs used as signal processors
> >
> >> Capacitors used as power amps
> >
> >> Varicaps used as opamp front ends
> >
> >how do you do those 3?
> >
> >> FR4 used as a thermometer
> >
> >Terrible capacitance tempco, but is it worth the additional circuitry you need to turn that into a temperature signal?
> >
> >
>
> Just make an LC or schmitt oscillator where a bit of the PCB is the
> capacitor. It's ideal for compensating FR4 problems elsewhere on the
> same board. An FR4 PCB cap has a tempco around -900 PPM/K.

Nice trick. I was guessing you used it as temp sensor for a power
pass element.

George H.

[John Larkin]

On Thu, 07 Dec 2017 15:57:27 -0800, Joerg <ne...@analogconsultants.com>
wrote:

I've heard a rumor that you have to pay a tax in the UK just for
having a television. But that's too silly to be real.

[Joerg]

That was always the case in Germany as well. AFAIK they now went farther
and made it a poll tax. You are by default presumed to have access to
radio and TV, even if just through a computer somewhere, so you must pay
radio and TV tax.

[Michael A Terrell]

John Larkin wrote:
>
> Remember flying-spot scanners?

I have one. It is part of a B&K 1077 TV Analyst.

Here is a photo from a unit of that series:
<http://www.labguysworld.com/1077B_049.jpg> shows the CRT, the slide
holder, and at the left side of the case is the phototube.

[Tom Gardner]

Tis (almost) true, I admit.

It has an interesting side effect: every hour contains >58 minutes
of TV program. And often a high quality programme.

And, of course, you aren't the product being sold.

Very few British people would have it any other way.

[John Larkin]

We get the BBC mysteries. It's shocking how many murders you guys
have.

[whit3rd]

On Thursday, December 7, 2017 at 2:55:03 PM UTC-8, Piotr Wyderski wrote:
> John Larkin wrote:


> > CRTs used as signal processors
>

> As storage elements -- yes, but processsing?

Yep, done with a swept function generator that makes a curled trace, and minimize
the transmitted light through a negative of a cloud-chamber track. When
the curvature matches the trace, the output light signal dip tells you what the
track curvature was...

Oscilloscope/photocell with a paper mask to make arbitrary function generator.

[tabb...@gmail.com]

On Thursday, 7 December 2017 23:02:05 UTC, Piotr Wyderski wrote:
> tabbypurr wrote:

> > VDF as valve in various apps.
>
> Why?

because one can? You do get light as well as sound. And VFDs are free. And they can run direct off the mains.


> > It does depend what you mean by legitimate.
>
> As strange a circuit as you wish, but without irreversible
> violation of its SOAR. BC107 used for switching kiloamperes
> wouldn't count. ;-)
>
> Best regards, Piotr

6w from a 1w IC may be a bit borderline then.


NT

[k...@notreal.com]

On Fri, 8 Dec 2017 01:09:24 +0000, Tom Gardner
<spam...@blueyonder.co.uk> wrote:

We invented this thing called the "fast-forward" button.

>And, of course, you aren't the product being sold.

Doesn't work that way.

>Very few British people would have it any other way.

Not surprising for socialists. My SIL is a Brit and wouldn't think
about returning.

[tabb...@gmail.com]

We do have tv tax, about £150 a year for colour, I forget what the B&W cost is now, if it still exists.

But quality programming? Er, no. The BBC's justification for the tax has largely ceased to exist.

PS put 2 coins in not 1, you get twice the time.


NT

[tabb...@gmail.com]

On Friday, 8 December 2017 01:18:34 UTC, John Larkin wrote:

> We get the BBC mysteries. It's shocking how many murders you guys
> have.

Those are fairly typical villages, some are worse. They only count murders officially once they're solved & thus proven. When you're over here it's not wise to dig up someone's plants.


NT

[John Larkin]

Yes, it's in the 1991 book:

https://www.dropbox.com/s/gm8ot0bqcbkd21o/Philbrick_Varicap_Amp.JPG?raw=1

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

[John Larkin]

Yeah, I've never seen a BBC mystery where the Chief Inspector failed
to find the murderer.

Sherlock had one get away, and Poirot let a train full of killers get
away with it.

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

[John Larkin]

My remote button of choice is OFF.

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

[John Larkin]

On Thu, 07 Dec 2017 12:36:29 -0800, Joerg <ne...@analogconsultants.com>
wrote:

>On 2017-12-07 09:51, Piotr Wyderski wrote:
>> Hello,

>>
>> just out of curiosity, could youl please name the weirdest
>> practical components abuses/entering the non-linear region/
>> unusual, non-obvious, but still legitimate applications you know of?

>> I think it is fun to learn about them, here is my list:
>>
>> 1. Saturable reactors and all that spawns from them.
>> 2. Parametric resonance-based magnetic digital circuits. (google =>
>> parametron)
>> 3. Negistor oscillator.
>> 4. Single-transistor photovoltaic (rly?) negative voltage generator.
>> 5. Transformerless valve audio amplifiers.
>> 6. Dynatron oscillator.
>> 7. Voltage regulator valves used as Geiger counters.
>>
>
>
>Making smoke :-)
>
>https://www.youtube.com/watch?v=rAB5AfpOd_0

Exploding parts is fun.

https://www.dropbox.com/s/4x34e1kisggy4de/ExFets.jpg?raw=1

https://www.dropbox.com/s/5it6rgc1wxcp8ah/Ex-Resistors.JPG?raw=1

https://www.dropbox.com/s/oz62u59ourty079/Z420_C1.JPG?raw=1

[John Larkin]

On Thu, 7 Dec 2017 13:56:03 -0800 (PST), whit3rd <whi...@gmail.com>
wrote:

>Contact wear (as in relay points) maximized
>and named 'electrical discharge machining'.
>

Relays can make hundred-volt pulses with sub-ns rise times.

[Piotr Wyderski]

tabb...@gmail.com wrote:

>>> VDF as valve in various apps.
>>
>> Why?
>
> because one can?

OK. :-)

> And VFDs are free.

The Noritake graphics VFDs are far from free.

Best regards, Piotr

[Tom Gardner]

There again, the Yanks beat the Brits.

Miss Marple (etc) couldn't have kept up with Jessica
Fletcher's workload: Cabot Cove has the highest
murder rate, followed by Ystad. (No doubt our
very own false-flag Putin puppet, Cursitor Doom, will
use the latter as evidence that Sweden is a dangerous
place!)

https://www.theguardian.com/media/mediamonkeyblog/2012/aug/23/fictional-tv-town-murder-rate
derived from the *wonderful* radio programme "More or Less",
where bona-fide statisticians examine popular claims to see
the degree of truth in them
http://www.bbc.co.uk/programmes/p00wzvls

[Klaus Kragelund]

On Friday, December 8, 2017 at 12:08:34 AM UTC+1, Piotr Wyderski wrote:
> pcdh...@gmail.com wrote:
>
> > Resetting an op amp integrator by inverting the power supplies. (Turns the ESD diodes into a bridge.)
>
> Powering and clocking an MCU at the same time by connecting a coil to
> its XTAL_IN pin and some other pin and using the ESD diodes as an RF
> bridge rectifier.
>
That's nice :-)

[Piotr Wyderski]

John Larkin wrote:

> Bell Labs made a CRT ADC for early digital phone systems. An electron
> sheet was deflected by the audio, and hit a grey-coded mask. 8 bit
> companding!

Now that's neat, never heard of!

> Remember flying-spot scanners?

Yes, I do.

> Hi-K dielectrics vary C radically with voltage. So a low-power DC bias
> can modulate a big AC signal.

Can you get to the 10:1 range using the off the shelf caps?
With magamps it's pretty a no-brainer.

> How about color TV HV rectifier tubes as xray sources?

Counts, but they were rather actively fighting with that
using the HV metal cages than using it to an adventage.

> They may have been tunnel diodes. Razor blades used to rust.

Assuming the price, availability and packaging isn't a problem,
would you find any use for tunnel diodes in modern applications
(in quantity, the bench-scale experiments don't count)?

Best regards, Piotr

[David Brown]

On 08/12/17 05:15, John Larkin wrote:
> On Thu, 7 Dec 2017 17:51:33 -0800 (PST), tabb...@gmail.com wrote:
>
>> On Friday, 8 December 2017 01:18:34 UTC, John Larkin wrote:
>>
>>> We get the BBC mysteries. It's shocking how many murders you guys
>>> have.
>>
>> Those are fairly typical villages, some are worse. They only count murders officially once they're solved & thus proven. When you're over here it's not wise to dig up someone's plants.
>>
>>
>> NT
>
> Yeah, I've never seen a BBC mystery where the Chief Inspector failed
> to find the murderer.
>
> Sherlock had one get away, and Poirot let a train full of killers get
> away with it.
>

Yes, but Poirot was Belgian, not British. And Sherlock Holmes was
inspired by a French detective (who also pioneered using fingerprints,
IIRC).

[David Brown]

We have the same sort of thing in Norway. And some of our TV "tax" is
used to buy in programs from the BBC.

The strange thing about having national television channels like the BBC
and NRK is that they are more independent than private ones. They are
not dependent on commercial financing, they don't have to appease
government bodies to keep renewing their licences, and they are not run
by shady gazillioneres with political motives (like Murdoch, or that guy
in the James Bond movie).

[Piotr Wyderski]

Tim Williams wrote:

> More involved tricks, I'm not sure, but that's a good example.

Yes, once you told me about the ADC, it's obvious that this
is a generic technique that can play back any waveform "recorded"
on the shielding "screen".

>> How? Electrostatic amplifiers based on saturable dielectrics? (another
>> item to be added to the list).
>

> Parametric amplifier, I assume.

I don't know, but not necessarily. If you apply enough DC bias to reach
the dielectric saturation knee, it's dual to an ordinary magamp. I'm
curious what dielectric was used.

Thanks, Piotr

[David Brown]

I would have guess Midsomer to be top of the list - but I suppose not
all the murders take place in the village itself.

Still, is the competition about quantity - or quality?

The Americans do the special effects better, and no one beats them for
TV explosions and gun battles - but I think British crime series beat
them in subtlety, plot, and humour.

For some reason, Norway has "Easter Crimes" ingrained in the culture -
for a couple of weeks around Easter, TV is full of murder mysteries.
There are so many that it involves a lot of complex planning to have
your DVR taping two series while you are simultaneously watching another
- you can't miss any of them. British series dominate, followed by
Scandinavian ones - American ones just don't count as /real/ murder
mysteries. (Things like CSI are popular in the rest of the year, but
that's just for a bit of shoot-them-up fun with cool looking lab work.
It's not a mystery.)

[Piotr Wyderski]

John Larkin wrote:

> I've heard a rumor that you have to pay a tax in the UK just for
> having a television. But that's too silly to be real.

No, it is not silly enough. In Poland you have exactly the same,
you pay a tax for *owning* a TV set (or a radio), not for watching it.
I repeat, it is for *owning a TV set*, not for the ability to receive
the broadcast. If you receive it on a laptop using an USB dongle, for
example, you don't pay the tax, because there is no TV set, you know...
The purpose is to sponsor the regime TV and radio stations.

Best regards, Piotr

[bill....@ieee.org]

And TV programs unsubtle enough that you don't miss anything by fast-forwarding through them

> >And, of course, you aren't the product being sold.
>
> Doesn't work that way.

The advertisers see it exactly that way. Krw hasn't realised this yet ...

> >Very few British people would have it any other way.
>
> Not surprising for socialists. My SIL is a Brit and wouldn't think
> about returning.

Britain isn't all that socialist. You have to sell the socialist principles as "fair play". And anybody who could put up with krw for any length of time has complex needs - which is to say, has to be as nuts as krw.

--
Bill Sloman, Sydney

[Tom Gardner]

Precisely.

They are also free to take more risks.

They can also "do" a "Faulty Towers" or "Young Ones"
without the risk of it degenerating as M*A*S*H did
over the years.

In the US "we" are the product being sold, and it
shows. Here we are the customer, and it feels like it.

[David Brown]

You mean for the 10 minute "get another beer and make more popcorn"
intervals between every 5 minutes of actual program - 3 minutes of which
is a recap of the last part of the show?


When we watch American shows, we invariably do so by "taping" it on the
DVR. The commercial stations here don't have anything like as many
commercial slots, or as high a percentage of advertising time. But even
without the adverts, you still get the "we'll be back after the break"
message followed by a re-cap to suit audiences with the short-term
memory of a goldfish with dementia.

(We still watch some American shows - some of your programs are good.)

>
>> And, of course, you aren't the product being sold.
>
> Doesn't work that way.

Yes, it /does/ work that way with national channels like the BBC or the
NRK. For their own programs, not only do you not have adverts but they
don't have product placement or other commercial endorsements.

>
>> Very few British people would have it any other way.
>
> Not surprising for socialists. My SIL is a Brit and wouldn't think
> about returning.
>

Everyone has their own preferences.

[Allan Herriman]

On Thu, 07 Dec 2017 15:29:36 -0500, bitrex wrote:

> On 12/07/2017 12:51 PM, Piotr Wyderski wrote:
>> Hello,
>>
>> just out of curiosity, could youl please name the weirdest practical
>> components abuses/entering the non-linear region/ unusual, non-obvious,
>> but still legitimate applications you know of?
>> I think it is fun to learn about them, here is my list:
>>
>> 1. Saturable reactors and all that spawns from them.
>> 2. Parametric resonance-based magnetic digital circuits. (google =>
>> parametron)
>> 3. Negistor oscillator.
>> 4. Single-transistor photovoltaic (rly?) negative voltage generator.
>> 5. Transformerless valve audio amplifiers.
>> 6. Dynatron oscillator.
>> 7. Voltage regulator valves used as Geiger counters.
>>

>>     Best regards, Piotr
>>
>>
>>
>>
> Korg MS-20 voltage-controlled filter, using reverse-biased BJTs as the
> variable resistance element:
>
> <http://www.aleph.co.jp/~takeda/radio/img/MS20Clone2.gif>
>
> Soviet Polivoks voltage-controlled filter, adjust cutoff frequency by
> current-controlling op-amp GBW:
>
> <http://m.bareille.free.fr/modular1/vcf_polivoks/vcf_polivoks_sh0.gif>
>
> Use a bridge rectifier as a variable resistance:
>
> <https://www.google.com/patents/US4039980?dq=yasuo
+nagahama&hl=en&sa=X&ei=ZMsnVc3QCMvFsAWsxIHwBA&ved=0CFUQ6AEwCA>
>


More VCFs:

I saw a 4069 used as a four channel matched voltage controlled variable
resistor in a VCF.
One of the remaining inverters was in the feedback path of an opamp to
linearise the control voltage - resistance characteristic.

This was in a guitar effects pedal. It was a phaser, and the phase
shift network had four single pole phase shifters in series.
Each stage had a series C and an R to
ground which was the N-ch fet in the inverter output. The inverter
-ve rail was at analog ground ( = mid rail for the opamps). The
inverter inputs and positive rail were connected to the control
voltage, which was driven from the linearising circuit.

The first time I looked at it, I thought WTF? How can that work? But
it sunk in after a few seconds.

There were four of these in series.

___
.--|___|--.
| |
| |
___ | |\ |
Vin --o---|___|---o---|-\ |
| | \ |
| | >-o------ Vout
| || | /
'----||-----o---|+/
|| | |/
|
Vcontrol |
+ ---. |
| | |
| |' |
'---| >O--'
|/ CD4069 (1 of 6)
|
|
GND

(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

The control voltage linearity was improved by a separate lineariser
circuit, using one of the spare inverters and an opamp, like this:


|\|
V in------|-\ ___
| >----|___|--+
I ref >-----+-----|+/ |
| |/| |
| |
| |
Vcontrol | |
+ ---+-------------------------+
| | |
| |' |
'---| >O--'
|/ CD4069 (1 of 6)
|
|
GND

(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Here, the 'R' synthesised is Vin / Iref

Allan

[David Brown]

Countries vary on the details of how national TV licences are handled.
The common one is that a household needs to have a TV licence if they
have a working TV. If you buy a TV in a shop, they will check that you
have a licence or register you for one if you don't. In theory, you can
avoid it - you could even get the TV antenna clipped off so that you
could not receive the signals. The license covers as many TV's as you want.

Most countries have had, or are having, debates about how to deal with
getting licence fees from households that don't have any normal TV's,
but watch via pads, telephones, Chromecast, etc.


There used to be "TV detector vans" that patrolled the streets, with
antennas and racks of equipment to spot people who had their TV's on.
If someone had a TV but was not registered as a licence payer, they'd
get a knock on the door and charged a fine. (In reality, the vans
equipment didn't actually do /anything/ - they could simply assume that
if people were at home in the evening, the chances are they were
watching TV.)

[Piotr Wyderski]

David Brown wrote:

> Countries vary on the details of how national TV licences are handled.
> The common one is that a household needs to have a TV licence if they
> have a working TV.

This is exactly how it works in Poland. A per-household "licence"
for owning at least one TV set. Or a radio, because they are handled
separately, the cost is lower then. Having a TV set implies having a radio.

> If you buy a TV in a shop, they will check that you
> have a licence or register you for one if you don't.

In Poland they are not allowed to check that. It's the buyer's
obligation to go to the post office and register. The post officers
can visit you at home to check that, but since they are not the Police,
you don't have to let them enter your property. Being sufficiently
rude is all one needs for not paying for the "licence".

Best regards, Piotr

[Tauno Voipio]

On 8.12.17 02:21, John Larkin wrote:
>
> Core memory is actually pretty weird.
>

Maybe the memory core logic in the British Elliott 803 computer
of yesteryear is then a bit more weird. It is possible to use
memory cores a logic elements. The fan-in and fanout are pretty
modest: around 3. The logic needs a three-phase non-overlapping
clock to keep the data flowing in the intended direction.

--

-TV

[jrwal...@gmail.com]

On Friday, 8 December 2017 10:39:57 UTC, David Brown wrote:

> There used to be "TV detector vans" that patrolled the streets, with
> antennas and racks of equipment to spot people who had their TV's on.
> If someone had a TV but was not registered as a licence payer, they'd
> get a knock on the door and charged a fine. (In reality, the vans
> equipment didn't actually do /anything/ - they could simply assume that
> if people were at home in the evening, the chances are they were
> watching TV.)

I thought they did actually receive the local oscillator leakage - but
maybe this stopped being effective when receivers got better shielded.

John

[David Brown]

I have heard a variety of explanations for what they might or might not
do. I suppose things like detecting the weak leakage signals could be
possible. But there is no way they could drive along the road and
pin-point which flat in a block of flats is watching TV - and it is in
the denser and cheaper housing areas where you would get the highest
rates of non-payment. So the real effect of the vans is psychological,
to make people think they can't get away with cheating.

[Gerhard Hoffmann]

Here in Germany it is even more rude.
Each and every household pays, whether there is a TV or not.
And if you have a home office, it is fairly easy to be counted twice.

The non-private state owned TV system is badly needed as a benefice
for retired polititians with certain, eh, merits.
They must make sure that is is independent, after all.

\Gerhard

[Tim Williams]

Most (all?) logic input protection diodes are actually BJTs between
substrate and VDD.

Pulling an input below VSS causes the majority* of that current to flow into
VDD, not VSS!

*The input pin is the emitter, substrate base, and VDD collector. Alpha is
small (alpha is emitter current gain), so a lot does still go into VSS (base
current).

VDD diodes don't have significant hFE, except maybe in a low-leakage
application where you're hammering on some pins. Typically, hFE is 0
between gates, and ~0.03 between inputs of a single gate (for multiple-input
types).

On that note, most modern logic latches up over 100mA. Latchup current is
limited by internal resistance, usually not much more than I_H. I measured
170mA on an 'HC.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: https://www.seventransistorlabs.com/

"Piotr Wyderski" <pete...@neverland.mil> wrote in message
news:p0bv3s$ds6$1...@node1.news.atman.pl...

[Joerg]

They didn't have the right inspecteur.

https://www.youtube.com/watch?v=cyPdQuSGcbs

--
Regards, Joerg

http://www.analogconsultants.com/

[Tim Williams]

From the bygone era:

Vacuum tube inverted operation. Use grid as plate, and plate as grid.
Dissipation is way lower, and mu_inv = 1/mu (which consequently means Rp is
extremely low, making this semi-popular for direct drive tube amps).

The balance of currents in tetrodes and pentodes. Namely: as plate voltage
drops (into the [voltage] saturation region), screen current shoots up.
(Cathode current remains ~constant, and the screen-plate system acts like a
long tailed pair upon that current.) Or if you vary Vg3, you can cut off
the plate, diverting current to the screen. Thus, dual-control pentodes can
be used as single balanced mixers (g1 = tail current, g3 = diff pair
voltage, g2 and a = output currents).

This leads to certain negative-resistance properties with a single tube:
http://www.r-type.org/articles/art-135.htm

Tetrodes: secondary emission results in a negative resistance region in the
normal plate curves. Mostly undesired and optimized out of newer types
(beam tetrodes), but old types (like the #24) had a strong effect.

Secondary emission was also harnessed in some types, e.g. EFP60. Of course,
that's not a bug, it's a feature.

[Phil Hobbs]

How about the cat detector vans of the Ministry of Housinge?

"Housinge?"
"It was spelled like that on the van. I'm very observant."

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
https://hobbs-eo.com

[k...@notreal.com]

On Thu, 07 Dec 2017 20:16:31 -0800, John Larkin
<jjla...@highlandtechnology.com> wrote:

>On Thu, 07 Dec 2017 20:45:32 -0500, k...@notreal.com wrote:
>
>>On Fri, 8 Dec 2017 01:09:24 +0000, Tom Gardner
>><spam...@blueyonder.co.uk> wrote:
>>

>>>> I've heard a rumor that you have to pay a tax in the UK just for
>>>> having a television. But that's too silly to be real.
>>>

>>>Tis (almost) true, I admit.
>>>
>>>It has an interesting side effect: every hour contains >58 minutes
>>>of TV program. And often a high quality programme.
>>
>>We invented this thing called the "fast-forward" button.
>>
>

>My remote button of choice is OFF.

We're not taxed on that one either.

[k...@notreal.com]

On Fri, 08 Dec 2017 11:30:20 +0100, David Brown
<david...@hesbynett.no> wrote:

>On 08/12/17 02:45, k...@notreal.com wrote:
>> On Fri, 8 Dec 2017 01:09:24 +0000, Tom Gardner
>> <spam...@blueyonder.co.uk> wrote:
>>
>
>>>> I've heard a rumor that you have to pay a tax in the UK just for
>>>> having a television. But that's too silly to be real.
>>>
>>> Tis (almost) true, I admit.
>>>
>>> It has an interesting side effect: every hour contains >58 minutes
>>> of TV program. And often a high quality programme.
>>
>> We invented this thing called the "fast-forward" button.
>
>You mean for the 10 minute "get another beer and make more popcorn"
>intervals between every 5 minutes of actual program - 3 minutes of which
>is a recap of the last part of the show?

There are 42-45 minutes of show for every hour broadcast, just as
there always has been. They do stack it up at the end but that's
marketing. Yes, that's how you use a FF button (surprised that you
had to be told but I guess all technology passes you by).

>
>
>When we watch American shows, we invariably do so by "taping" it on the
>DVR. The commercial stations here don't have anything like as many
>commercial slots, or as high a percentage of advertising time. But even
>without the adverts, you still get the "we'll be back after the break"
>message followed by a re-cap to suit audiences with the short-term
>memory of a goldfish with dementia.

But you get to pay tax *AND* watch commercials. Fun! There are no
recaps after commercials. You're lying.

>(We still watch some American shows - some of your programs are good.)
>
>>
>>> And, of course, you aren't the product being sold.
>>
>> Doesn't work that way.
>
>Yes, it /does/ work that way with national channels like the BBC or the
>NRK. For their own programs, not only do you not have adverts but they
>don't have product placement or other commercial endorsements.

Not in the sense that "you're the product" on the Internet. Your
viewing tastes aren't sold (individually), as they are anytime you
browse the Internet.

>>
>>> Very few British people would have it any other way.
>>
>> Not surprising for socialists. My SIL is a Brit and wouldn't think
>> about returning.
>>
>
>Everyone has their own preferences.
>

Yes, apparently snowflakes are drawn to socialism. like moths to fire.

[Wond]

On Thu, 07 Dec 2017 15:59:27 -0800, John Larkin wrote:

> On Thu, 7 Dec 2017 23:54:59 +0100, Piotr Wyderski
> <pete...@neverland.mil> wrote:
>
>>John Larkin wrote:
>>

>
> "Foxhole radios" used a rusty razor blade as the detector. They may have

> been tunnel diodes. Razor blades used to rust.

They didn't _have_ to be rusty- you had to put the point of the safety
pin right at the edge of the lettering. Gillette blue blades were good.
My first radio, from a Radio Craft magazine.

[John Larkin]

On Fri, 8 Dec 2017 10:32:07 +0100, Piotr Wyderski
<pete...@neverland.mil> wrote:

>John Larkin wrote:
>
>> Bell Labs made a CRT ADC for early digital phone systems. An electron
>> sheet was deflected by the audio, and hit a grey-coded mask. 8 bit
>> companding!
>
>Now that's neat, never heard of!
>
>> Remember flying-spot scanners?
>
>Yes, I do.
>
>> Hi-K dielectrics vary C radically with voltage. So a low-power DC bias
>> can modulate a big AC signal.
>
>Can you get to the 10:1 range using the off the shelf caps?
>With magamps it's pretty a no-brainer.

This is extreme:

https://www.dropbox.com/s/ilppasx0ym7b98y/Ccap_CV.JPG?raw=1

>
>> How about color TV HV rectifier tubes as xray sources?
>
>Counts, but they were rather actively fighting with that
>using the HV metal cages than using it to an adventage.
>
>> They may have been tunnel diodes. Razor blades used to rust.
>
>Assuming the price, availability and packaging isn't a problem,
>would you find any use for tunnel diodes in modern applications
>(in quantity, the bench-scale experiments don't count)?

Germanium TDs are still made and used as zero-bias RF detectors. I
don't think anyone still makes the switching types.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

[tabb...@gmail.com]

On Friday, 8 December 2017 04:15:52 UTC, John Larkin wrote:

> On Thu, 7 Dec 2017 17:51:33 -0800 (PST), tabbypurr wrote:
> >On Friday, 8 December 2017 01:18:34 UTC, John Larkin wrote:
> >
> >> We get the BBC mysteries. It's shocking how many murders you guys
> >> have.
> >
> >Those are fairly typical villages, some are worse. They only count murders officially once they're solved & thus proven. When you're over here it's not wise to dig up someone's plants.
> >
> >
> >NT
>
> Yeah, I've never seen a BBC mystery where the Chief Inspector failed
> to find the murderer.
>
> Sherlock had one get away, and Poirot let a train full of killers get
> away with it.

those programs are in contrast to reality, where attention is liable to not be paid when warranted.


NT

[tabb...@gmail.com]

On Friday, 8 December 2017 09:22:27 UTC, Piotr Wyderski wrote:
> tabbypurr wrote:
>
> >>> VDF as valve in various apps.
> >>
> >> Why?
> >
> > because one can?
>
> OK. :-)
>
> > And VFDs are free.
>
> The Noritake graphics VFDs are far from free.
>
> Best regards, Piotr

Indeed, when new. When in dead VCRs, nukes etc all VFDs are free.

Someone made a dual audio triode using VDF technology, it makes no sense.


NT

[tabb...@gmail.com]

On Friday, 8 December 2017 09:47:58 UTC, David Brown wrote:

> The strange thing about having national television channels like the BBC
> and NRK is that they are more independent than private ones. They are
> not dependent on commercial financing, they don't have to appease
> government bodies to keep renewing their licences,

Not sure which alternate reality that's from

[Piotr Wyderski]

John Larkin wrote:

> https://www.dropbox.com/s/ilppasx0ym7b98y/Ccap_CV.JPG?raw=1

Great contribution, thanks! So you can do 10:1 at the rated voltage.
This effect can have some interesting niche applications.

Best regards, Piotr

[DemonicTubes]

On Thursday, December 7, 2017 at 4:55:39 PM UTC-7, pcdh...@gmail.com wrote:

> That trick of putting current boosters controlled by resistors in series with the supply pins of an op amp.
> Cheers
>
> Phil Hobbs

I'm not understanding this one. Can somebody provide me with a hint?

[John Larkin]

His cop pal said out loud that Father Brown was the angel of death.
And everywhere that Lord Peter went, even on his own honeymoon, bodies
appeared.

>
>Still, is the competition about quantity - or quality?
>
>The Americans do the special effects better, and no one beats them for
>TV explosions and gun battles - but I think British crime series beat
>them in subtlety, plot, and humour.

Absurd plots. There is something to be said for straightforward Philip
Marlowe brutality.

--

John Larkin Highland Technology, Inc

picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

[Lasse Langwadt Christensen]

some variation of this

https://consort3.files.wordpress.com/2010/10/widlarboost2.jpg

[Tim Williams]

"John Larkin" <jjla...@highlandtechnology.com> wrote in message
news:mshl2dtqqig08k74v...@4ax.com...

> This is extreme:
>
> https://www.dropbox.com/s/ilppasx0ym7b98y/Ccap_CV.JPG?raw=1

Why does the left side show an asymptote?

Normally, C levels out to ~nominal at 0V, and usually rises slightly in the
first few volts.

[whit3rd]

On Friday, December 8, 2017 at 1:32:13 AM UTC-8, Piotr Wyderski wrote:
> John Larkin wrote:
>
> > Bell Labs made a CRT ADC for early digital phone systems. An electron
> > sheet was deflected by the audio, and hit a grey-coded mask. 8 bit
> > companding!
>
> Now that's neat, never heard of!

The patent makes interesting reading: it was also an introduction of Gray code
(by Frank Gray, it's never 'grey code')

<https://www.google.com/patents/US2632058>

[John Larkin]

Here's an over-the-top version, to make a super-precise current amp to
drive an NMR gradient coil.

https://www.dropbox.com/s/mtnrinyvzmspeov/L620_Out.jpg?raw=1

This is a "perfect class B" circuit, effectively class B with zero
crossover error.

[John Larkin]

Oh, here's the corresponding leakage curve.

https://www.dropbox.com/s/dlet57gmlntxx9h/Ccap_Leakage.JPG?raw=1

I think it failed (small bang) about 270 volts.

--

John Larkin Highland Technology, Inc

[Clifford Heath]

On 09/12/17 01:48, David Brown wrote:
> On 08/12/17 15:20, jrwal...@gmail.com wrote:
>> On Friday, 8 December 2017 10:39:57 UTC, David Brown wrote:
>>
>>> There used to be "TV detector vans" that patrolled the streets, with
>>> antennas and racks of equipment to spot people who had their TV's on.
>>> If someone had a TV but was not registered as a licence payer, they'd
>>> get a knock on the door and charged a fine. (In reality, the vans
>>> equipment didn't actually do /anything/ - they could simply assume that
>>> if people were at home in the evening, the chances are they were
>>> watching TV.)
>>
>> I thought they did actually receive the local oscillator leakage - but
>> maybe this stopped being effective when receivers got better shielded.
>>
>
> I have heard a variety of explanations for what they might or might not
> do. I suppose things like detecting the weak leakage signals could be
> possible. But there is no way they could drive along the road and
> pin-point which flat in a block of flats is watching TV

How much radio DF (foxhunting) have you done?
I'd be very surprised if you couldn't get a very good
directional fix on any LO leak, before even "hunting
on strength".

- and it is in
> the denser and cheaper housing areas where you would get the highest
> rates of non-payment. So the real effect of the vans is psychological,
> to make people think they can't get away with cheating.

Clifford Heath

[Clifford Heath]

On 08/12/17 21:22, Allan Herriman wrote:
> On Thu, 07 Dec 2017 15:29:36 -0500, bitrex wrote:

>
>> On 12/07/2017 12:51 PM, Piotr Wyderski wrote:
>>> Hello,
>>>
>>> just out of curiosity, could youl please name the weirdest practical
>>> components abuses/entering the non-linear region/ unusual, non-obvious,
>>> but still legitimate applications you know of?
>>> I think it is fun to learn about them, here is my list:
>>>
>>> 1. Saturable reactors and all that spawns from them.
>>> 2. Parametric resonance-based magnetic digital circuits. (google =>
>>> parametron)
>>> 3. Negistor oscillator.
>>> 4. Single-transistor photovoltaic (rly?) negative voltage generator.
>>> 5. Transformerless valve audio amplifiers.
>>> 6. Dynatron oscillator.
>>> 7. Voltage regulator valves used as Geiger counters.
>>>
>>>     Best regards, Piotr
>>>
>>>
>>>
>>>

>> Korg MS-20 voltage-controlled filter, using reverse-biased BJTs as the
>> variable resistance element:
>>
>> <http://www.aleph.co.jp/~takeda/radio/img/MS20Clone2.gif>
>>
>> Soviet Polivoks voltage-controlled filter, adjust cutoff frequency by
>> current-controlling op-amp GBW:
>>
>> <http://m.bareille.free.fr/modular1/vcf_polivoks/vcf_polivoks_sh0.gif>
>>
>> Use a bridge rectifier as a variable resistance:
>>
>> <https://www.google.com/patents/US4039980?dq=yasuo
> +nagahama&hl=en&sa=X&ei=ZMsnVc3QCMvFsAWsxIHwBA&ved=0CFUQ6AEwCA>
>>
>
>
> More VCFs:
>
> I saw a 4069 used as a four channel matched voltage controlled variable
> resistor in a VCF.
> One of the remaining inverters was in the feedback path of an opamp to
> linearise the control voltage - resistance characteristic.
>
> This was in a guitar effects pedal. It was a phaser, and the phase
> shift network had four single pole phase shifters in series.
> Each stage had a series C and an R to
> ground which was the N-ch fet in the inverter output. The inverter
> -ve rail was at analog ground ( = mid rail for the opamps). The
> inverter inputs and positive rail were connected to the control
> voltage, which was driven from the linearising circuit.
>
> The first time I looked at it, I thought WTF? How can that work? But
> it sunk in after a few seconds.
>
> There were four of these in series.
As published in one of the Australian electronics magazines
in the late 70's. I still have the version I built, hopped
up with extra stages. I might even have some recordings of
the band we used it in.

Clifford Heath.

> ___
> .--|___|--.
> | |
> | |
> ___ | |\ |
> Vin --o---|___|---o---|-\ |
> | | \ |
> | | >-o------ Vout
> | || | /
> '----||-----o---|+/
> || | |/
> |
> Vcontrol |
> + ---. |
> | | |
> | |' |
> '---| >O--'
> |/ CD4069 (1 of 6)
> |
> |
> GND
>
> (created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)
>
> The control voltage linearity was improved by a separate lineariser
> circuit, using one of the spare inverters and an opamp, like this:
>
>
> |\|
> V in------|-\ ___
> | >----|___|--+
> I ref >-----+-----|+/ |
> | |/| |
> | |
> | |
> Vcontrol | |
> + ---+-------------------------+
> | | |
> | |' |
> '---| >O--'
> |/ CD4069 (1 of 6)
> |
> |
> GND
>
> (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
>
> Here, the 'R' synthesised is Vin / Iref
>
> Allan
>

[Lasse Langwadt Christensen]

once 99.9% have a TV it is easier to just make a list of households that
doesn't pay and got tell them to stop cheating ;)

here they changed it from "TV license" to a "media license", so if you have
tv,radio,internet or smart phone you have to pay

[DemonicTubes]

Interesting and clever circuit, thank you for sharing.

Please forgive my ignorance: What are the opto-couplers for? Also, R5 and C7, are those for impedance matching to your load?

[John Larkin]

To shut off the output fets when we want truly zero output current.
NMR is insanely sensitive, and sometimes we want very zero gradient
field.

> Also, R5 and C7, are those for impedance matching to your load?

That damps resonances in the cables and the load coil, to keep the
fets from oscillating. Audio amps usually have a similar thing, which
they call a Zobel Network.

The amp drives the high side of the gradient coil. The low side
returns to ground through a current shunt, and there is an overall
closed-loop control on the actual current. This amp is nowhere good
enough open-loop.

[John Larkin]

On Fri, 8 Dec 2017 13:34:07 -0600, "Tim Williams"
<tmor...@gmail.com> wrote:

>"John Larkin" <jjla...@highlandtechnology.com> wrote in message
>news:mshl2dtqqig08k74v...@4ax.com...
>> This is extreme:
>>
>> https://www.dropbox.com/s/ilppasx0ym7b98y/Ccap_CV.JPG?raw=1
>
>Why does the left side show an asymptote?

Hand drawn, ran out of paper. The numbers are right.

>
>Normally, C levels out to ~nominal at 0V, and usually rises slightly in the
>first few volts.

This cap might do that, but I didn't notice. My main concern was using
it as a bypass or a switching regulator output, so I just wanted the
gross curve. More capacitance wouldn't bother me!

Here's another one:

https://www.dropbox.com/s/d8tyke1minfc5c6/Samsung_47U_CV.JPG?raw=1

--

John Larkin Highland Technology, Inc

[k...@notreal.com]

The compliance costs seem silly (though Brits have always had a silly
streak). Just tax everyone. Pay it from general funds, or whatever.

[John Larkin]

On Fri, 8 Dec 2017 11:05:45 +0100, Piotr Wyderski

<pete...@neverland.mil> wrote:

>John Larkin wrote:
>

>> I've heard a rumor that you have to pay a tax in the UK just for
>> having a television. But that's too silly to be real.
>

>No, it is not silly enough. In Poland you have exactly the same,
>you pay a tax for *owning* a TV set (or a radio), not for watching it.
>I repeat, it is for *owning a TV set*, not for the ability to receive
>the broadcast. If you receive it on a laptop using an USB dongle, for
>example, you don't pay the tax, because there is no TV set, you know...
>The purpose is to sponsor the regime TV and radio stations.
>
> Best regards, Piotr
>

Do they tax books too?

How about if you sing in the shower?

[Lasse Langwadt Christensen]

they have their own funds so they are "independent" though most of the board are politicians and the government set how much they can collect

and it means it is easy to see how much they get, and complain about it

[Lasse Langwadt Christensen]

> I've heard a rumor that you have to pay a tax in the UK just for
> having a television. But that's too silly to be real.
>

don't some of your tax money end up paying for PBS?

[alie...@gmail.com]

On Thursday, December 7, 2017 at 3:59:39 PM UTC-8, John Larkin wrote:

>
> How about color TV HV rectifier tubes as xray sources?

Scientific American had an Amateur Scientist article on rolling your own.

Scared my mother when I built that one.


Mark L. Fergerson