Plasma transistor

Isn't that what Joerg makes from time to time?

On a sunny day (Tue, 28 Oct 2014 16:08:26 -0400) it happened "Tom Miller" wrote in :

As far as I understand this it is a small thyratron:

As switch - logic gate - yes. Als LINEAR device (transistor) that would be difficult.

Also I am quite sure that nuclear radiation can trigger the gas...

So, wait for it in the shop... :-) Tjernobyl... :-)

Another goofy press-release invention. Sounds useless and, especially, unreliable. A transistor with a built-in plasma etcher.

Related:

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

The multivibrator is cool.

Here's a 2 megawatt plasma transistor:

The thing that it was used to trigger ran at somewhat higher power.

Has anybody get the data sheet for this gadget?

On a sunny day (Tue, 28 Oct 2014 18:26:46 -0500) it happened "Tim Williams" wrote in :

I like this very much, thank you for posting that link.

Now I never have to buy transistors again...

Wonder how fast, how high frequency you can get with an LC.

He's also got a CdS-cum-MOSFET, and there's the CdS-pair-cum-UJT:

Tim

On a sunny day (Wed, 29 Oct 2014 07:51:53 -0500) it happened "Tim Williams" wrote in :

Cool, I have some UJTs from ebay, but this, with 2 CDS cells and a LED, I have never seen before. Learned some new trick :-). It is great how he goes into basic theory too.

Main advantage of UJT oscillators is that those are not very supply voltage sensitive, as it is all about that semiconductor resistor ratio.

Someone used to make a TO3 packaged CdS photoresistor, the idea being to make an AC power amp, with a small lightbulb as the input.

On a sunny day (Wed, 29 Oct 2014 08:48:28 -0700) it happened John Larkin wrote in :

In the old tubes based teefee studio in the audio mixer they used CdS cells with a light bulb mounted in some tube to control the volume of each audio channel. One of our jobs was to replace and calibrate those things on a regular basis so the faders would work correctly. Seems to make a nice noise free control.

The bummer about CdS and CdSe cells was their extreme instability with time, temperature, and illumination history. They were fine in places like Wein bridge oscillators where absolute value stability doesn't matter.

They made nice choppers, too. HP made a DVM that went down to 1 mV full-scale needle deflection. The input chopper and output demod were CdSe cells with a light bulb and a clock-motor-light-chopper wheel. Cool.

The HP425A works like that, but the low scale is 10 uV fullscale. It has current ranges from 10 micro-micro-amperes (we'd say 10 pA) up to 3 mA.

I have an HP 7035B plotter which uses this: judging by the austere design and lengthy revision history, it doesn't at all look like a traditional HP instrument (aside from the print quality of the manual); I think it was designed by another company which was bought by HP back in the day.

Looking at the circuit board, you might be quite perplexed by the use of only two 2N3055s (on small heatsinks) to supply bidirectional drive to two motors, but it makes perfect sense as you follow the circuit.

The photocells in question are very "narrow" (little or no interdigitation) and TO-39 packaged; they are coupled to neon tubes via some fishpaper tubes or something like that.

Tim

Thanks. :)

A shame about the shaky camera though... I need a proper tripod one of these days.

That 'Powermaster' of mine goes pretty low, I think under 100 ohms in daylight.

Tim

Writing traffic tickets from three states away? A laser show from the ISS? Or, the future's so bright, you have to wear shades...

Since I probably already have a little purple light all my own, I Googled.

What looks to be the same data table appears on a Japanese page, about halfway down.

These guys

Matt Roberds