Thank You Wilfred Klatt

RE: Thank You Wilfred Klatt

eye-zen — Fri, 18 Aug 2017 22:23:28 GMT

aahhhh - wonderful valves - i still use them everyday - whenever iturn my stereo amplifier on or decide to play my guitar... Yes i use valve amplifiers - for my stereo its one i homebuilt 30 yrs ago and it still runs a dream - uses 12ax7 and 12au7 valves in the preamp stage and 2 el34s in the final stage.

As for guitar well im old school - i own a 1963 marshall valve plexi - Still the iconic rock and roll amplifier of all time ....

And yes valve amplification does make a difference - it DOES seem warmer and more alive than semiconductor amplification - although i must be honest some of the newer microcontrolled amp simulators can get close and i expect on a blind listening test it would be extremely difficult to pick them... my 2c's worth to a great discussion. And yes i had a wilfred Klatt in my younger days - His name was Ken Saxon and he was a ham radio operator who built all his own gear - all valve stuff too - and he instiled in me an interest in electronics and valves that has remained with me for almost 50 yrs...

RE: Thank You Wilfred Klatt

DAB — Mon, 10 Jul 2017 17:36:25 GMT

Great project John.

Yes, we all had someone who helped fan to flames of a budding engineer or maker.

I do remember the old light beam devices.

A simple relay device to turn equipment or lights on or off when someone broke the beam.

Predates the IR laser based security beams.

DAB

RE: Thank You Wilfred Klatt

the-dubster — Mon, 10 Jul 2017 17:13:02 GMT

Nice read there John, like Mark I was also lucky(ish) enough to be there at the back end of valve technology. I do remember fixing an old Valve/ Transistor hybrid TV many MANY moons ago - I'm sure that's what did for my back!!

I do love digging old stuff out occasionally and seeing if I can bring it back to life (my local cemetery has banned me). . . . . . . .

I have a bunch of Nixie Tubes in an old timer/counter, one day I'll make a replacement for my rather modern looking Sunrise Clock.

Until then I'll live vicariously through those who actually get around to doing stuff!!

RE: Thank You Wilfred Klatt

mcb1 — Mon, 10 Jul 2017 10:30:54 GMT

Very interesting.

I hadn't really thought about sensing light back in the valve days.

I was lucky enough to work with valves when I started, but they were being pushed aside rather quickly by semiconductors.

It is rather amazing that in less than one generation, we've progressed from valves, to discrete, then to small modules, smd and microprocessors.

Mark

RE: Thank You Wilfred Klatt

jc2048 — Mon, 10 Jul 2017 09:18:01 GMT

Thanks, John, that's fascinating. (And thank you Wilfred Klatt, without whom you might not be here blogging.)

You immediately got me puzzling over the light sensor. I've always been aware of photomultipliers, but didn't realise people were using sensors like this (effectively the 'photo' without the 'multiplier').

There's a site here selling secondhand ones

http://www.sphere.bc.ca/test/photo-tubes.html

There are some really beautiful tubes on that page.

According to that, what you've got is a 'gas photodiode'. So I guess the large surface would be the cathode [stop me if I'm getting this wrong], and the wire at the focus down the centre would then be the anode. And it's the photoelectric effect (that Einstein wrote his famous paper about) that results in the surface emitting electrons which then make their way to the anode. If that page is right, the light current is only of the order of 1uA, so it's just as well that the second tube has a high input impedance and can make use of that to control the relay. What would the target material be? Tungsten perhaps, or would it be something more exotic? And what role does the gas play? [I'm just musing out loud - I don't expect an answer.]

Just found this - an RCA app note

http://www.tubebooks.org/Books/Atwood/RCA%201941%20Phototubes.pdf

They're careful not to say what the target material is (trade secret I suppose and it looks like it varies anyway, depending on the spectral response required). The gas is to improve the sensitivity. Again they don't say what gas it is, though they do say that it glows blue if you raise the anode voltage to the point where there's a continuous discharge [which they're obviously cautioning against]. Seems like a major market for these devices back then was the movie industry (for reading the soundtrack off the edge of a film).

I assume that they've painted the tubes to stop the whole thing latching up (the glow from the second tube feeding light back to the sensor and holding it on). Wonder what it was used for in a power generation context?

I can remember tubes from radio and TV sets and, specifically, the repairman calling to swap the non-functioning ones in the black-and-white TV set that we rented whenever it stopped working. Although I've never designed with them [I wouldn't know how, though apparently they're a bit like MOSFETs in their operation], I do get nostalgic when I see glass envelopes containing small wire sculptures. That era must have been the high point when it comes to the aesthetics of component design - now we just have boring lumps of black resin to look at.

RE: Thank You Wilfred Klatt

shabaz — Mon, 10 Jul 2017 06:47:00 GMT

Hi John,

It was very interesting reading about this! Great repair too.

Thanks to Wilfred Klatt and yourself, many people are inspired by your blog posts.