I have some G4S10 thyratrons. Have been playing with ideas such as guitar effects and synth use, but why not rectification. The thyratron rectifiers I've seen are using the grids to control the output, kinda half wave PWM of sorts. But I just want to use them as rectifiers, no fancy control.
I see on one thread here that the grids should go to the power transformer, leave plates floating, and that's it. But surely that can't be right? The grids are only to turn the device on. As a rectifier it should be on the whole time.
So is it not right to connect the grid to the cathode?
Also, I see claims of 'choke input only' but thyratron's magnificance is their incredible pulse current durability, is it not? So I'd think a cap input supply is no prob...?
Any tips before I wire this up? Thanks.
I see on one thread here that the grids should go to the power transformer, leave plates floating, and that's it. But surely that can't be right? The grids are only to turn the device on. As a rectifier it should be on the whole time.
So is it not right to connect the grid to the cathode?
Also, I see claims of 'choke input only' but thyratron's magnificance is their incredible pulse current durability, is it not? So I'd think a cap input supply is no prob...?
Any tips before I wire this up? Thanks.
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Thanks I've seen that. I am thinking of making a variable b+ on a guitar amp, where thyratrons are controlled to give added 'sag' or compression.
But for Hifi I just want to use them as straight rectifiers. Nothing complex at all. I have yet to see such simple use of them, I guess b/c that is a waste of a thyratron. But I have them, want ot use them, am lazy, just want a plain high voltage for my Hifi amp.
I guess it's time to just do it and see...I'm sure many others have some thyratrons laying around collecting dust.
Maybe time to try a coil gun...
But for Hifi I just want to use them as straight rectifiers. Nothing complex at all. I have yet to see such simple use of them, I guess b/c that is a waste of a thyratron. But I have them, want ot use them, am lazy, just want a plain high voltage for my Hifi amp.
I guess it's time to just do it and see...I'm sure many others have some thyratrons laying around collecting dust.
Maybe time to try a coil gun...
Thyratron's won't turn on unless their grid is made positive or negative with regards to the cathode. In a lot of cases the gas forms a screen around the grid once turned on. I built a version of the Teletype PSU - XG1-2500 Thyratron's. - YouTube This is the best source of info I found on thyratron's - https://frank.pocnet.net/other/Philips/Philips_ThyratronsForModernIndustry_1961.pdf
Andy.
Andy.
It has a screen grid, so a little more quirky but effectively the same.
The on-state voltage drop is fairly constant, rather than a nicer resistance characteristic that helps smooth the edges of the current waveform (a major attraction of normal valve rectifier diodes).
The 1Apk current waveform limit is very limiting, and indicates you need careful attention to turn-on and normal operating conditions. Perhaps either look up charts, or use sim like PSUD2 (although they don't have a model for a thyratron afaik).
You may also need to ensure compliance with a heater warm-up time.
The on-state voltage drop is fairly constant, rather than a nicer resistance characteristic that helps smooth the edges of the current waveform (a major attraction of normal valve rectifier diodes).
The 1Apk current waveform limit is very limiting, and indicates you need careful attention to turn-on and normal operating conditions. Perhaps either look up charts, or use sim like PSUD2 (although they don't have a model for a thyratron afaik).
You may also need to ensure compliance with a heater warm-up time.
I brought a thyratron blinker to Burning Amp 2019 - The guts were in a small box with a compact SMPS for high voltage, minus bias, grid driver and a filament supply, with a 3C23 mercury vapor thyratron on top. The thyratron operated as a triggered relaxation oscillator, and delivered pulses of blue light...
I also have a simiar setup continuously driving an 833a mercury vapor rectifier, no high voltage needed for that tube.
I am contemplating doing something similar for the Xenon-filled versions of these tubes - a bit more complex because of the higher striking voltage for the Xenon-filled rectifier.
I also have a simiar setup continuously driving an 833a mercury vapor rectifier, no high voltage needed for that tube.
I am contemplating doing something similar for the Xenon-filled versions of these tubes - a bit more complex because of the higher striking voltage for the Xenon-filled rectifier.
Did some measurements with a low voltage transformer, ca +-35Vp output. Compared to a BYW29E soft recovery diode. Half wave rectification into 1kohm resistor load, and two cap values, one 47uF and one 300uF.
One very interesting thing with the thyratron is how it will not conduct untill it has ca 17V over it, so it does not rectify very 50Hz sine. The harmonics are therefore starting at lower frequencies, as low as 2Hz with a low 1mA load.
But the harmonics created by the way the thyro turns on and off is not so good I think, creating more higher frequency hash than the reference silicon diode.
Different values for the cathode resistor helps. No resistor and the harmonics are greater. Have not experimented much yet...
The lower frequency of conductance can place the main harmonic lower than hearing which may seem good, but the higher hamonics are not good, besides the capacitance must be higher for the same ripple, further complicating the thing.
One very interesting thing with the thyratron is how it will not conduct untill it has ca 17V over it, so it does not rectify very 50Hz sine. The harmonics are therefore starting at lower frequencies, as low as 2Hz with a low 1mA load.
But the harmonics created by the way the thyro turns on and off is not so good I think, creating more higher frequency hash than the reference silicon diode.
Different values for the cathode resistor helps. No resistor and the harmonics are greater. Have not experimented much yet...
The lower frequency of conductance can place the main harmonic lower than hearing which may seem good, but the higher hamonics are not good, besides the capacitance must be higher for the same ripple, further complicating the thing.
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I think the reason for the increased ringing with the thyrotron is the very low capacitance of 2-3pF. This lets the transformer inductance ring easier since it does not damp it down, while a BYW29 has huge amounts of capacitance (ca 200pF at 1V) compared to tube rectifiers. If I place a 10-20pF cap across the thyratron it might help... Or ?
Yes it seems this thyrotron turns on when Vp>17-18V. So it depends on the load, and cap value, as to how fast the voltage drops low enough to make the thyro conduct again. So with high enough load, or small enough C, it can conduct every cycle. Alternatively with a light load, one can get it to conduct very seldomly, my test at 1mA load and 47uF it was at 2Hz. Had I used more capacitance, it will be even slower.
So if I tame the high frequency hash, it may be interesting in some applications. Not sure it is useful at all tho.
So if I tame the high frequency hash, it may be interesting in some applications. Not sure it is useful at all tho.
Your circuit is very crude , they use grid driver circuits so the conduction is controlled . It seems that hydrogen filled are produced even today for radar , laser , very fast switching . Peak anode voltage can be 40KV , so they can't be replaced with semiconductors at least in a simple way .
For diy electronics you could use them for light maybe ...
For diy electronics you could use them for light maybe ...
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I happen to have some hydrogen ceramic thyratrons, if you still want to try that... it's JAN 8765 to be specific. I see some fantasy prices for those on ebay... but I am not interested in waiting 200 years to sell them so I'm sure we can work something out.
Yes indeed, as crude as they get...or as simple as possible. I tried to explain in my first post that I want to use the thyratrons as simple rectifiers, NOT fancy complex controlled rectifiers. I purposely made that single half wave rectifier to test them and then since that was so simple I figured why not compare to a decent soft recovery Si diode.
I asked if anyone had inputs on using thyratrons as simple rectifiers, no one did, so I built the circuit while on a Teams meeting...
And of course, if I actually build a rectifier circuit it will be full wave, so it'll get plenty fancy.
They do indeed work as rectifiers, but their low impedance when they trigger seems to create high order harmonics, not sure that is a good thing. If I ever get the urge I might try to tame them.
I was looking for something much bigger, the 8765 would only make 8-10 kW power in the induction heater I had in mind. I needed a 100 times more. Anyway, I am over 70 now and those days are gone, but thanks for the offer
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