Hmmm, Remember first ever popular transistor RCA CK722 PNP Ge junction type? When I got one of them at such a high price and built a small receiver with it, what an excitement. Was back in the '50s. Now I am using florescent lights and dimmers in the house. Waiting for LED lights to become cheap in price. Tony, VE6CGX
According to Tony Hwang :
A thyristor is not a vacuum tube. Thyristors are semiconductors - "four layers of alternating N and P-type material" according to Wikipedia. Some sources consider thyristor to be synonymous with SCR, others have thyristor include GTOs, Triacs, SJTs, SITH and MCTs too.
Didn't have much call to play with vacuum tube switching circuits, power or otherwise - most of my playing around with tubes was RF, with RF mid-power amp tubes and 0D3-type regulator tubes being the more exotic stuff.
That said, we may be getting access to a 60' radio telescope dish to do a little serious radio astronomy. The dish steering system is a vacuum tube and electric motor implementation of an H-bridge, similar to that used to steer things like shipboard radars. The modern semiconductor version is used in the small scale for hobby robots.
This has an example circuit for the small scale:
We don't believe the vacuum tube portion will still be working (the dish been locked for ~15-20 years), so we're thinking that we will have to replace everything but the movement motors with modern solid-state very high power H-bridge modules. Eg: a hundred A at 600V or something silly like that.
I've played with those (and mentioned them backthread)
He meant thyratrons, I think the 2d21's were the smallest ones and I don't remember the number of three huge ones that controlled our Lepel 400KW 250KHz alloy bearing surface welders.
It gets hard to remember all these names when you're old enough to remember real power control. Also, no one mentioned carbon piles, another version of early "dimmers" ;-)
-- larry / dallas
Yeah, I figgered later he meant thyratron.
The closest I got to those (which isn't very close) is to the particle accelerator in the basement of the University of Toronto that, if I recall correctly, was doing pulses in the megawatts range at 400Mhz with Klystrons.
Aside from that, my exposure to the "big" stuff was multi-kilowatt tube transmitters.
You got that right.
This is not an answer to any of the above, but i thought it may be of interest. I have in my posesion, a 1920,s dimmer switch. It is a large 'jelly mould' shape in brass with brown ceramic mount. At first glance it looks like a standard togle type light switch exept for the size - diam 95mm, depth 90mm - and the fact that it has many ventilation holes in the brass cover. The toggle however slides up and down. This is connected to two blades which in turn slide against two sets of carbon pads. Iy was new and boxed when I found it while clearing out an old store and to my knowledge has never been used. It is stamped with a rating of 70 watts & 110 volts DC and after a bit of digging around I have dicovered that very early electricity was generated localy and supplied as 110volts dc to a few of the better properties in our town. I think that the supply was intented for very early domestic lighting only.
Does anyone know anything else/conflicting etc
What kind of light bulbs are you using?
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