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Old-fart electronics quiz

J

John Woodgate

What's the difference between an EL84, UL84 and PL84?

The first letter of the type number or the heater characteristics
What did Armstrong invent?

An up-market range of British cars (with Siddeley) or FM
What is a PI tank?

One that carries Professional Indemnity insurance or shunt C-series L-
shunt C
How do you make a phototransistor out of an OC71?

Trade it or scrape the paint off
What is the formula for a parallel plate capacitor?

Cu + O2 + 4N2 or C = 8.9 x Ak/d pF, k = relative permittivity.
What is a constant K filter?

One with all the component values equal to 1024, or a legacy type which
has long been superseded.
What is rhe meaning of the following classes of emission, A1, A2 and A3?

A1 is the best and the others are not as good. Or A1 = CW, A2 = MCW, A3
= voice modulation.
What does SSTV stand for?

Simon Stanley Thompson-Vermont (who owns an Armstrong-Siddeley) is a
rather intolerant person, so he doesn't stand for very much. Or Slow-
Scan Television.
What is a BALUN?

An old working place, the opposite of a NULAB. Or a balanced-to-
unbalanced transformer.
 
J

John Woodgate

I read in sci.electronics.design that N. Thornton <[email protected]>
It must have been enough to raise the patients heartrate, as an opamp
running on 200v with no visible form of safety protection at all, not
even a cord grip, and the patient hooked up via saltwater buckets, is
not exactly confidence inspiring.

I went to a lecture by a medical electronics pioneer (he did a lot of
work on ultrasound scanners) who told the story of the development of
the defibrillator. At first, they used 120 V dry batteries, but nurses
WOULD put instruments across the terminals and flatten them. So then
they used the 240 V mains supply, rectified, but that was too much
juice. It wasn't that it killed patients, because most of them died
anyway, but when it killed a few surgeons ...

So someone looked at the problem and came up with the capacitor-
discharge type as seen on TV, TIME after TIME after TIME! (;-)
 
J

John Larkin

~Negative-resistance zener
^^^^^^^^^^

Actually, you can semi-legitimately think of a td as a zener diode
whose junction is so thin that the breakdown voltage crosses over zero
to the other side. So the initial current peak is actually the edge of
the zener breakdown.
Yup, but with a 4th terminal (2nd gate) for turnoff

Crystal-controlled

Can't you make an LC Pierce?
Astable multivibrator

Or maybe a flip-flop with AC coupled, maybe diode-steered, trigger
inputs.
and K means 10%

OK.

John
 
M

Max Hauser

Joe said:
Speaking of interesting old-farts...
Where is Bob Pease when we need him?
He would have fun with this.

He did, I believe. Remember that this is a re-posting, it has been here
once or twice in the past. Bob, like me, is not particularly new to
sci.electronics (nor is the observation new that the 'Net is full of junk,
it has always been). Also, productivity is not an _absolute_
disqualification for reading these groups
 
J

John Larkin

means youre dealing with a history enthusiast. Imagine 512M of core
memory! I'm trying to remember the spacing of the cores, lets say 1/4"
x 1/4". A 512M sheet would then be about 22000 inches long on each
side. To reduce that to a cube with say 1/4" spacing between planes,
we'd get a cube of 49" on each side, a 4 foot cube. I'm surprised, as
that sounds doable. Why then did many core memory computers come with
just 1k?

My first computer, a PDP-8, had 4k of 12-bit memory, and I managed to
run control system simulations on it, in Focal. That memory cost about
a dollar a byte. I vaguely remember a press release in Electronic News
where IBM announced a breakthrough: core memory had just broken the
$50,000 per megabyte boundary.

Near the end, the cores were barely visible, and a 4 kbit plane was
just a couple of inches square.
a valve, not certain if its a rectifier or a thyratron, probably the
latter.

A very stupid toob?



John
 
F

Frank Bemelman

John Woodgate said:
One with all the component values equal to 1024, or a legacy type which
has long been superseded.

Nope, it's that Ctrl-K manouvre that JT makes with every nerveous
twist he makes ;)
 
M

Martin Eisenberg

Matt said:
Martin Eisenberg said:
Randy Yates wrote:
[...snipped out of courtesy...]
What is *that*?

That's the easy way to remember the resistor color coding
scheme. The 3 color bands on a resistor give its value in ohms.
The first two bands are digits (Black = 0, Brown = 1, Red = 2,
Orange = 3, etc), and the 3rd band is a power of 10. Brown,
black, red, for example, is 10 *10^2 ohms, or 1 KOhm. The last
band is silver or gold for 10 or 5% tolerance.

Thanks to all who answered. I thought it was a mnemonic from the
context in Randy's post, but I neglected to make the connection to
the English color names because English is not my mother tongue.
Since I'm minoring in EE, I'll probably be related a native relative
of that -disgusting- sentence sooner or later ;)
For those of you who find Randy's version offensive, there is a
nicer version that's more difficult to remember. I don't
remember it.

Jim Weir gave another version which I find indeed harder to remember.
If anyone knows yet another one, I'd like to hear it!
The version I originally learned is even more offensive than
Randy's -- it began with "black boys" in order to disambiguate
the colors that start with "B". I'm young enough to have grown
up during a period of politcal correctness, so hearing a
mild-mannered acquaintance recite that mnemonic exactly *once*
was sufficient to burn the image of those words onto the the
slab of neurons responsible for my long term memory.

It's certain that my soul was somehow diminished in the process,
but I have never, ever, forgotten how to read a resistor.

LOL!


Martin
 
J

John Larkin

Programmed Data Processor. The story behind the name is told in a
Creative Computing magazine circa 1977.

They called them PDPs so people could order them without the
management approvals associated with buying a "computer."

Didn't know that was an acronym. I know the plural is Vaxen.

We had a dual-VAX setup: one was Max the Vax and the other was Maxine
the Vaxine.

John
 
J

Jan Panteltje

Quotes

"Anyone who has had actual contact with the making of the inventions
that built the radio art knows that these inventions have been the
product of experiment and work based on physical reasoning, rather than
on the mathematicians' calculations and formulae. Precisely the opposite
impression is obtained from many of our present day text books and
publications." - Edwin H. Armstrong
This is important, think Farnsworth and the fusor, he invented the TV AND
the fusion reactor, now go in sci.physics and see test their knowledge.
See the fuss they make for a few milliseconds fusion... Farnsworth had
continuous fusion.
 
J

Jan Panteltje

What's the difference between an EL84, UL84 and PL84?
6.3 V heater, 150 mA heater, 300mA heater, all are penthode
audio output (some 4 watts?)
What did Armstrong invent?
'Small step for man, Big step for man kind' hehe
What is a PI tank?
New US weapon...
No pi filter output in transmitter you mean (supply via choke)?
How do you make a phototransistor out of an OC71?
remove black paint.
What is the formula for a parallel plate capacitor?
Have to look it up oops.
What is a constant K filter?
K? dunno
What is rhe meaning of the following classes of emission, A1, A2 and A3?

What does SSTV stand for?
Slow Scan Television, I actually did it!
What is a BALUN?
Coupling method for antenna for example
You?

;-)

I will think about some things myself.....
But you guys know everything ....
This I was actually asked at some exam (sixties):
When you have an IF amp with a 10.7MHz and a 455 KHz (or 450 hehe JW)
tuned ciruit in series, would you design the 10.7 or the 455 (450) connected
to the collector of the driving transistor, and why.
 
J

John Larkin

This is important, think Farnsworth and the fusor, he invented the TV AND
the fusion reactor, now go in sci.physics and see test their knowledge.
See the fuss they make for a few milliseconds fusion... Farnsworth had
continuous fusion.

The ultimate test for lab-scale fusion - electrolytic cold fusion,
multipactor, whatever - is whether the inventor promptly died from
neutron irradiation. If he didn't, he didn't achieve fusion.

John
 
N

N. Thornton

John Woodgate said:
I read in sci.electronics.design that Jim Thompson
4ax.com>) about 'Old-fart electronics quiz', on Sun, 18 Jan 2004:
We definitely had them in Europe, but I never owned one, being content
to keep one TV for 28 years. I'm not aware that there was a need for
frequent readjustment, and I used to service TVs for food in those days.

I think spot wobblers were quite common here, and considered almost
necessary on large screens. I think....


Regards, NT
 
N

N. Thornton

Active8 said:
maybe. he did develope the feedback amp for sure. It was the
feedforward amp prior to that, but at the time, ou couldn't get
good tubes cheap enough to make the feedforward amp work right.

Do tell us more...


Regards, NT
 
J

John Woodgate

I read in sci.electronics.design that Jan Panteltje
01.evisp.enertel.nl>) about 'Old-fart electronics quiz', on Sun, 18 Jan
2004:
When you have an IF amp with a 10.7MHz and a 455 KHz (or 450 hehe JW)
tuned ciruit in series, would you design the 10.7 or the 455 (450) connected
to the collector of the driving transistor, and why.

That's a question of a very different nature from the LED one. It's
about electronics, for a start!

It's also not so easy to answer, unless you know details of the typical
design of such stages. Most graduates would not know, and no discredit
for that.

What were your answers (both of them!)?
 
R

Randy Yates

Matt Timmermans said:
Martin Eisenberg said:
Randy Yates wrote:
[...snipped out of courtesy...]
What is *that*?

That's the easy way to remember the resistor color coding scheme. The 3
color bands on a resistor give its value in ohms. The first two bands are
digits (Black = 0, Brown = 1, Red = 2, Orange = 3, etc), and the 3rd band is
a power of 10. Brown, black, red, for example, is 10 *10^2 ohms, or 1 KOhm.
The last band is silver or gold for 10 or 5% tolerance.

For those of you who find Randy's version offensive, there is a nicer
version that's more difficult to remember. I don't remember it.

The version I originally learned is even more offensive than Randy's -- it
began with "black boys" in order to disambiguate the colors that start with
"B". I'm young enough to have grown up during a period of politcal
correctness, so hearing a mild-mannered acquaintance recite that mnemonic
exactly *once* was sufficient to burn the image of those words onto the the
slab of neurons responsible for my long term memory.

It's certain that my soul was somehow diminished in the process, but I have
never, ever, forgotten how to read a resistor.

Thank you Matt!
 
P

Paul Burridge

Scrape the black paint from the outside of its tiny glass test-tube
looking package.

Is that the device where the three leads exit the base in a straight
line with the centre one slightly off-set towards one of the outer
leads and a paint-spot on the edge near the bottom of the
encapsulation for assisting in pin identification? Mullard, wasn't it?
 
S

Sigvaldi Eggertsson

John Woodgate said:
I read in sci.electronics.design that Al Clark <[email protected]>


It must be terribly dull in Iceland then. What do they do in the long
summer evenings and the loooong winter nights? Between eruptions, of
course.

We talk about sex of course but the favorite topic of discourse seems
to be politics and weather.
 
S

S.M.Taylor

Paul said:
Is that the device where the three leads exit the base in a straight
line with the centre one slightly off-set towards one of the outer
leads and a paint-spot on the edge near the bottom of the
encapsulation for assisting in pin identification? Mullard, wasn't it?

Yep. PNP.First transistor I ever used, courtesy of my father.

Steve
 
J

John Crighton

Yep. PNP.First transistor I ever used, courtesy of my father.

Steve

I bought three of those OC71s in the early 1960's for a guinea,
my auntie who was a tayloress at that time earned four guineas
per week. Just for interest Paul, they were used in a
Super regen. RC receiver with a valve (XFY34) RF amplifier,
miniature little thing. 1.5V heaters and 22 volt main supply.
The valve cost me 15/6 from the Clyde model dockyard,
a hobby shop along Argyle street in Glasgow. The transistors
came from a disposal shop near "The Barras," an open air
market place similar to Pettycoat lane/Portobello road in
your area.

John Crighton
Sydney
 
J

Jerry Avins

Fred said:
I consider the rape scandal to be minor compared to the
institutionalized tacit approval of murder of civilians. The most
egregious case recently publicized about those so-called Special Forces
and their murder of Vietnamese civilians is a case in point. The
individuals involved were not real Special Forces- they appear to be a
collection of truly sub-normal IQ types the Army threw together to go
behind enemy lines and harass the Vietcong. The reality was that they
avoided the Vietcong and harassed hapless Vietnamese farmers- summarily
murdering them capriciously. Their so-called actions were of absolutely
no tactical value whatsoever. There was an official investigation, and
the Army concluded that many of the acts were murder, but they went on
to conclude that prosecution would serve no useful purpose. I consider
this to be a major obscenity. Recent interviews with some of these swine
show that they have absolutely no remorse whatsoever- they did it to
survive they say. This is total BS- they are psychopaths and morons- and
the worst crime against nature was that they did survive.

Fred,

I don't disagree. I believe, however, that rape at home and wanton
murder in a battle area arise from the same mindset. The great war
horrors from Vietnam that I heard directly from the perpetrator was told
as an adventure story, like reminiscences of an overnight hike in camp.

The narrator was a pilot who flew daily bombing sorties over North
Vietnam for two weeks straight, then went to Tokyo for a week's R&R. His
orders were to fly a big loop over the ocean to drop his bombs on those
days when he couldn't, because of weather or flak, reach his assigned
target. (One doesn't land with bombs on board!) He seemed very proud
that he and other squadron members had worked out a way to get home
quicker. They would climb high, then dive, then pull up sharply and
release their bombs while climbing. That way, the bombs fell on the
countryside (and, when they wanted extra kicks, in towns) entirely at
random. What fun!

One day, flying home, A spotter on a hilltop fired on him with his
rifle. As he turned to begin a strafing run, the spotter dived into a
hole in the ground and disappeared. The same thing happened the next
day, but after that, he saved his "surplus" bombs for the mountain top.
The pilot and the spotter began a routine. The spotter would shoot at
him with rifle fire as he began his bombing run, then dive into the
bunker. as the plane passed over, the spotter would emerge and fire
again. Then one day, the spotter opened fire with a 20 mm canon (or
something similar), putting some holes in the plane. The pilot told us
of his skill in quickly leaving the scene. When I asked what happened
the next time, he said, "I never went back. He was trying to *kill* me!"
When I asked the pilot what he had been trying to do, he said, "That's
different. He's a gook." In Colorado Springs, he would probably have
said, "That's different. She's a broad." Same detachment, same result.

Jerry
 
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