Answers to old-fart electronics quiz

[Martin Blume]

We once bought a "transient recorder" instead of a printer because
only the IT department was allowed to buy IT equipment.

Another reason: by second wife was a computer late in WW II. She
worked in a room with lots of others working a Frieden
calculators.

I have a book from my father's library (from the 50s) where they
talk about "computers". It took me a while to figure out that they
meant human beings (and lots of them ...).

Martin

 

[Martin Eisenberg]

4. Who developed the op amp, and when?

Electronic amplifiers used in feedback loops to simulate other
things (electronic analog computation) appeared about 1938.
That, by the way, is how the term "analog" infiltrated
electronics; earlier one heard of power, audio, radio, and
occasionally pulse and "switching" electronics.

So the idea was that an "analog" device behaves analogously to
another system, do I understand that right?

relaxation oscillator

I would like to take the opportunity to ask just what that
"relaxation" is about. Google gives all kinds of references but no
definition of the term that I've found in the heap.


Martin

 

[Ian Bell]

Max Hauser wrote:

snip

24. What is a couplate? a micromodule? the difference between thin-film
and thick-film hybrid circuits?

Thin-film hybrid circuits contain components (resistors, capacitors,
wiring)
deposited with a screening process onto a ceramic substrate. In
thick-film hybrids, the components are discrete but leadless and they are
attached to a
ceramic substrate after separate fabrication. In both cases, transistor
and IC dice also get attached after separate fabrication. These circuits
are called "hybrid" because they mix discrete-component and
integrated-circuit t echnologies.

Thick film hybrids also have screened resistors - at least in the UK.

Ian

 

[Jan Panteltje]

Did you ever find an EQ80 - nonode FM detector?

Nope

 

[John Larkin]

Max Hauser wrote:

snip


Thick film hybrids also have screened resistors - at least in the UK.

Ian

And thin-film hybrids have vacuum deposited - not screened - resistors
and conductors.

John

 

[JeffM]

relaxation oscillator

I would like to take the opportunity to ask
just what that "relaxation" is about.
Google gives all kinds of references
but no definition of the term that I've found in the heap.
Martin Eisenberg

I didn't have any problem with Google (2nd listing):
http://www.google.com/search?hl=en&...ation+oscillator"+glossary&btnG=Google+Search

They don't use resonant tanks
and, with the exception of Blocking Oscillators, don't use an L.
They are non-sinusoidal: they conduct, then stop conducting (relax).

 

[Max Hauser]

I stand happily corrected! -- M

 

[Max Hauser]

JeffM seems to have nailed it.

The whole subject of "first-order" oscillators (i.e., single timing or
energy-storage element), which might at first seem simple, is rich with
theoretical implications. One of the many talented graduate students at the
Technical University of Delft wrote a good thesis on first-order oscillators
around 1993 that is in my library.

"Relaxation" oscillators as a practical matter charge up a storage element,
sense a level of charge, and then -- do NOT stop the charging (that's a
regulator, as in a toilet-tank mechanical feedback system) but instead,
release the charge, irrevocably, until it has dropped to a level to start
charging again Unijunction transistors (UJTs) are an excellent
one-component sensor/discharger for a capacitive relaxation osc. and served
me well in timers and sundry gadgets 30 years ago. FAR less power than the
sometimes-notorious "555" timer and less finicky. (My counterparts today
however throw around PIC microcontrollers as readily as I deployed
Unijunctions.)

The best example I saw of a relaxation oscillator consisted of the
distinguished professor Donald O. Pederson (who more or less started
academic IC research in the US about 1960) late one afternoon sitting in the
back of a seminar after he had introduced the speaker. He very rhythmically
nodded off, caught himself, and straightened up, restarting the periodic
cycle.

 

[N. Thornton]

From: "N. Thornton" <[email protected]>

The famous "long-tailed pair" patent, so named of course because the HUGE
resistor in the cathode path was often drawn longer than usual due to its
large value -- draftsman's (UK draughtsman's) option, I've seen it even into
the 1960s -- was about 1936, I have the info, just not handy; it was
British, assigned to the BBC if I recall. That was the basis for most DC
amplifiers with tubes that were not "chopped." My own point concerned the
popularization and elaboration of the operational amplifier as a mainstream
product. Substantive information about developments of op amps in the
19-teens would be very welcome and could even be a major historical
contribution; pls get in touch if you find it.

This is curious, I could have sworn the picture of the ECG was from
well before then. So either
my memory's amiss, though I cant think how I could square that
interpretation with my library,
or else perhaps it used a different differential input circuit,
or less likely, it could be a surprise to us all.

When I get the chance to go over there I'll try and dig it up. Then
I'll withhold it from you till youve told me every amplifier class
that exists

Regards, NT

 

[John Woodgate]

I read in sci.electronics.design that N. Thornton <[email protected]>

Then
I'll withhold it from you till youve told me every amplifier class
that exists

Legitimate ones (standardized by IEC): A, AB, B (AB and B with suffixes
1 for no grid current and 2 for with grid current in valve/tube
amplifiers), C, D.

Obscure (no proper definitions): E, F

Plausible: G, H (output stages with multiple supply voltages)

Proprietary: S, T.

 

[John Woodgate]

I read in sci.electronics.design that Max Hauser <[email protected]>

The best example I saw of a relaxation oscillator consisted of the
distinguished professor Donald O. Pederson (who more or less started
academic IC research in the US about 1960) late one afternoon sitting in the
back of a seminar after he had introduced the speaker. He very rhythmically
nodded off, caught himself, and straightened up, restarting the periodic
cycle.

So THAT'S why they are called 'relaxation oscillators'.

 

[Bob Stephens]

I didn't have any problem with Google (2nd listing):
http://www.google.com/search?hl=en&...ation+oscillator"+glossary&btnG=Google+Search

They don't use resonant tanks
and, with the exception of Blocking Oscillators, don't use an L.
They are non-sinusoidal: they conduct, then stop conducting (relax).

One that I see all the time is the igniter circuit for gas ranges or
heaters. A voltage charges up a capacitor exponentially until it reaches
the breakdown voltage of a neon bulb which fires, depleting the charge on
the cap and the whole cycle begins again. The output is applied to a step
up coil which feeds a spark gap, igniting the gas.

Here's a question that's always interested me. In the old days, gas stoves
were inherently fail-safe. The pilot flame heated a thermopile which
generated a current to a solenoid valve in the gas line. If the pilot went
out, the thermocouple would cool and the spring loaded solenoid would close
off the gas supply - beautiful. Today's electrical controls allow the user
to turn the knob part way, releasing gas into the room without necessarily
turning the knob all the way into the ignite position right away - or ever.
How come UL and CSA etc. don't have a fit about this?


Bob

 

[Mike]

Answers to answers to "Answers" (to date)
....



If I were moderating this group (God forbid) I would prohibit such questions
and others like them, because they can be hard to answer definitively but
easy to feel certain about.

Indeed, but history does not progress by censoring the questions until the
answer is certain. In the absence of certainty, some theories could be
refuted, even if none was offered in its place. In my view, "We don't know"
is a perfectly valid answer to many historical questions.

-- Mike --

 

[N. Thornton]

I read in sci.electronics.design that N. Thornton <[email protected]>
'Answers to old-fart electronics quiz', on Fri, 23 Jan 2004:

Legitimate ones (standardized by IEC): A, AB, B (AB and B with suffixes
1 for no grid current and 2 for with grid current in valve/tube
amplifiers), C, D.

Obscure (no proper definitions): E, F

Plausible: G, H (output stages with multiple supply voltages)

Proprietary: S, T.

Thanks John, maybe I'll let Max off now No seriously I'll dig it up
when I have the chance.


Regards, NT

 

[N. Thornton]

I read in sci.electronics.design that N. Thornton <[email protected]>
wrote (in <[email protected]>) about
'Answers to old-fart electronics quiz', on Fri, 23 Jan 2004:

Legitimate ones (standardized by IEC): A, AB, B (AB and B with suffixes
1 for no grid current and 2 for with grid current in valve/tube
amplifiers), C, D.

Obscure (no proper definitions): E, F

Plausible: G, H (output stages with multiple supply voltages)

Proprietary: S, T.

Hi

For anyone interested theres EER as well - no nothing to do with him.
This explains it:

http://lists.contesting.com/archives/html/Amps/2002-10/msg00189.html


Any more I'm all ears!

Regards, NT

 

[John Woodgate]

I read in sci.electronics.design that N. Thornton <[email protected]>

Thanks John, maybe I'll let Max off now No seriously I'll dig it up
when I have the chance.

OK. For extra credit, what is a 'pi mode' output stage?

 

[Ian Bell]

I didn't have any problem with Google (2nd listing):
http://www.google.com/search?hl=en&...ation+oscillator"+glossary&btnG=Google+Search

They don't use resonant tanks
and, with the exception of Blocking Oscillators, don't use an L.
They are non-sinusoidal: they conduct, then stop conducting (relax).

Used to make simple ones with a series R connected to parallel neon tube and
capacitor. Connect to high volts supply, capacitor charges up until neon
strike voltage reached which then discharges the cap and the cyle repeats.
Sawtooth waveform is typical output of a relaxation osc.

Ian

 

[John Larkin]

The best example I saw of a relaxation oscillator consisted of the
distinguished professor Donald O. Pederson (who more or less started
academic IC research in the US about 1960) late one afternoon sitting in the
back of a seminar after he had introduced the speaker. He very rhythmically
nodded off, caught himself, and straightened up, restarting the periodic
cycle.

Earthquakes, too.

John

 

[Jim Thompson]

Earthquakes, too.

John

I did that once at a seminar an ICE associate and I were presenting at
Kodak in Rochester.

After a red-eye flight my associate went first, speaking in a most
soothing monotonic voice.

I promptly fell asleep and rolled out of a student desk in the back of
the auditorium, brushing the light switches as I fell to the floor...
plunging the whole place into darkness.

That was more than thirty years ago. There are still people at Kodak
who remember the event ;-)

...Jim Thompson

 

[Tweetldee]

[repost]

8. Traditional op-amp ICs were designed whenever possible to run on +- 15
volts. Why that voltage?

Allowing a clean output swing of +- 10V, a convenient scale for their
original service as analog-computer computation elements. Vaccuum-tube op
amps set the trend earlier with +- 100V standard output swings. See also
Note 3 on op amps.

Welcome back.

This brought to mind a fairly long running discussion, from a few years
ago, that never came to a definitive conclusion. (That you probably
know the answer to).

Why was the 7400 TTL power supply 5+/-5% volts?


Mark Zenier [email protected] Washington State resident

Speed considerations were a primary driving factor. The risetimes,
falltimes, etc., that were chosen as desing goals for the TTL family
dictated that the voltage excursions be kept to a minimum. Transistor
technology had not yet reached the low voltage potentials of today's
semiconductors. A low Vcc level had to be chosen, and 5V was a good
compromise for power consumption, voltage excursions, rise and fall times,
etc for the technology.
--
Tweetldee
dgmason44 at comcast dot net (Just subsitute the appropriate characters in
the address)

Never take a laxative and a sleeping pill at the same time!!