1. Home
  2. Electronics (German)
  3. Unusual functions of cheap parts
  4. Page 3

Unusual functions of cheap parts

Certainly.

I used arc welding glasses when conducing these experiments.

Some trivia:

In the silent film era, actors had eye problems due to the UV radiation from arc studio lamps.

Most of the usable illumination from the arc lights is actually from the glowing carbon electrodes.

"Automatic arc lights" used a solenoid in series with the arc to keep the distance constant between the poles regardless of carbon electrode burnout. I assume that if this is to be used with a AC arc light, both the moving coil as well as the static coil should carry the arc current.

Paul OH3LWR

Reply to
Paul Keinanen
Loading thread data ...

E.G the CMOS 4007. See the old handbooks for a '100dB amplifier' based on a RCA chip - there was a wiring error in that old description - IIRC it was 3800? - whatever, the 4007 is the same chip.

Murray vk4aok

Reply to
Murray

The Motorola McMOS handbook (2nd edition 1974) warns about this usage by pointing out that by cascading three such AC coupled stages, the last stage will be saturated by the noise from the first stage.

Paul OH3LWR

Reply to
Paul Keinanen

formatting link

Yes, a co-worker at a former job and myself peeled the top off a 22pin dram chip (we went through several brands to find one that had the memory array in one large area rather then 4 smaller areas) and then replaced the top with a microscope slide cover. By re-reading the array and timing how long it took for the ones to decay to zeros (or visa versa) we were able to get about 4 levels of gray scale. A tiny lens from a broken camera view finder was mounted above the chip and I rigged up a way to move the chip back and forth to focus. Our first 'subject' was a 60w light bulb. We were using an AppleII (gives you an idea of how long ago this was) to do the image processing. We both went 'crazy' when we saw the '60 Watt' from the top of the bulb on the screen! The resolution of our camera wasn't even as good as early SSTV (maybe 64 x 64 pixels) but it did work.

Reply to
wa2mze(spamless)

Take one P channel Jfet and one N channel Jfet and connect them in series so the two sources are together, connect the gate of each transistor to the other one's drain. This is known as a lambda connection, and if you plot the voltage vs current from drain to drain you will see a negative resistance region, usually around 3v (depending on the transistors). The circuit will work as a tunnel diode oscillator up to 100-200mhz.

Reply to
wa2mze(spamless)

Did you know that a carbon arc acts as a negative resistance? Run the arc on DC and put an LC tuned circuit in series with the arc (coil of heavy copper tubing) and you have a powerful oscillator.

Reply to
wa2mze(spamless)

connect the

after

necessary.

reliable

heater) or

ignition.

out.

I

put

course

Exactly-when I was a kid we made them like this all the time. As I recall, it came from "700 scientific experiments, with illustrations"...

>
Reply to
Rick

I've used a light bulb in series with a rectifier to charge a car battery (just make sure that line ground goes to chassis ground ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

John Devereux wrote in news: snipped-for-privacy@cordelia.devereux.me.uk:

To save power, use the LEDs of a backlight to measure the ambient light to decide to switch the backlight on or not.

M.

--
Bitte auf mwnews2@pentax.boerde.de antworten.
Reply to
Matthias Weingart

We worked with a company that was developing an xray imager, and was buying very expensive electrically conductive glass (gigohms per square sort of range.) They discovered that certain welding glass was identical and about 1/20 the price.

John

Reply to
John Larkin
[...]

you mean forward biased? Reverse breakdown of most cheap LEDs is IIRC around 100V.

Oliver

--
Oliver Betz, Muenchen (oliverbetz.de)
Reply to
Oliver Betz
[.....]

btw, do you know a standard complementary pnp-transistor for the 2N2369, such like 2N3905 but with higher ft and less feedback capacitance? It seems that the manufactorers have almost no data on their internet pages.

mfg. Winfried

Reply to
Winfried Salomon

Going the other direction, I used the elements from a toaster as a load to discharge wet-cell lead-acid batteries. It was a discharge/charge cycling test.

John

Reply to
John - KD5YI

A 2N2369 is a gold-doped NPN, gold-doped to kill storage time and improve recovery from saturation. I don't recall any PNP device with gold-doping... or the equivalent.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

As a youngster I played with TTL DIP-ICs in my chamber and my parents next room felt that the tv was going crazy. The pins had long wires...

- Henry

schrieb im Newsbeitrag news: snipped-for-privacy@g43g2000cwa.googlegroups.com...

Reply to
Henry Kiefer

The 4007 is the classic crystal oscillator circuit. Don't forget the temperature characteristics!

- Henry

"Murray" schrieb im Newsbeitrag news:43884488$0$12455$ snipped-for-privacy@per-qv1-newsreader-01.i>

Reply to
Henry Kiefer

That is not new to me but thanks! Is the oscillator useful at 150MegHz? Modulable? Maybe I can make transmitter... Tell us more, please.

cu - Henry

"wa2mze(spamless)" schrieb im Newsbeitrag news:tT_hf.27576$ snipped-for-privacy@bignews6.bellsouth.net...

I

diode,

diode.

another

some

Reply to
Henry Kiefer

Don't forget the LED as an low-noise zener diode with integrated function control. Some high-fidelity enthusiasts use this in good audio amplifiers.

- Henry

"ehsjr" schrieb im Newsbeitrag news:R3thf.9922$BU2.983@trndny01...

I

diode,

diode.

another

some

Reply to
Henry Kiefer

There even exists LED specially taylored to the needs of doing duplex operation.

- Henry

"Frithiof Andreas Jensen" schrieb im Newsbeitrag news:dm6msq$bvk$ snipped-for-privacy@news.al.sw.ericsson.se...

light

yield

LED.

Reply to
Henry Kiefer

Bob Pease of National Semi mentioned a ONE AND ONLY transistor circuit above/under voltage rail converter (with detailed theory). I cannot remember the details. But interesting if sometime a slightly voltage behind the power rail is needed. For example to power a CMOS Opamp now doing rail-input.

- Henry

Reply to
Henry Kiefer

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.