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thyratron rectifier

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#21
dave slagle said:

If you need to get more than the 350V from the 394, you need to limit the current to the grid and I found that a 1K resistor from grid to plate allowed me to go upwards of 600V where I ran out of rotation on my variac. I do think I noticed a change in sound when run this way an I'd be interested if Ginluca would try the different configurations and report back.

dave
Click to expand...

That's something to try! Thanks for the tip. I am in the process of building a circlotron and I will again use thyratrons (the bigger WE393As this time) ... I'll avoid the mixed bridge. Soundwise, was it better or worse?
 
#22
Hi Gianluca.

I found that the 393 will not give you any more voltage than the 394 used grid as plate. It essentially behaves as a 394 with double the filament draw. (same goes for the 323) if you need more voltage you need to go to the 287 or the 354.


dave
 
#23
I know... I just use them as I found a cheap source for NOS WEs and they are prettier than the smaller 394.

354 is a hell of filament ... 17A, isn't it? I never found one. Large globe tubes are cutier, they are indeed gorgeous. I have 1 NOS globe 866A by RCA ... still looking for a companion. :xeye:

Gianluca
 
#24
just fired some of these puppies up.... dave

img_4578_150.jpg
 
#26
coresta said:
Hi , this is the heart of the systeml . The variable condenser will change the slope of the sinus voltage fed to the grid and thus change the conducting time of the conducting periode of the gas ... exactly the same as an halogen lamp fed by a variable triac "variator" 😉
Click to expand...

o.k. - understood - how big i can expect to have that cap....pF, nF, uF...??
i am total idiot related thyratrons......


kevinkr said:



Coresta is dead right, the left hand transformer provides the grid voltage for firing the tube each half cycle, the phase shift network changes the firing angle so that the half wave output can be "chopped" to vary duty cycle and hence effective power into the load, and the right hand transformer provides the voltage to the load. This is basically a half wave lamp dimmer.. :devilr:

I am not sure whether or not grid and plate should be tied together, I'm just wondering about the dissipation rating of the grid, you are using it in ways for which it was not intended.
Click to expand...


ohhh.... so the right transformer is actually the power transformer and the left one is providing the grid bias voltage.........this is still very confusing to me - i must admitt - can somebody draw a schematic with parts values that can be expected for power supply of lets say 200Vdc and using some of the thyratrons mentioned.....323, 394, 354 or something..... the intended current ... lets say 100mA... can somebody do the favour for me PLEASE.....
 
#27
sunrise said:

can somebody draw a schematic with parts values that can be expected for power supply of lets say 200Vdc and using some of the thyratrons mentioned.....323, 394, 354 or something..... the intended current ... lets say 100mA... can somebody do the favour for me PLEASE.....
Click to expand...


Hey! Never mind the schematic you posted. Just use the thyratron as you usually do with rectifiers but tie the grid to the hi voltage and leave the plate alone. With a choke input you will need 250V+250V at the secondary of the power tranny (well something near that value ... you know, it depends on a number of factors). You can series connect the filaments to a 5V secondary to heat the thyratrons.

Gianluca
 
#35
394a wiring

Gluca said:
Ciao

I am using them in my 211 preamp. I believe I am drawing something around 50-60mA. Its a full bridge (thyratrons + solid state diodes) to get 500VDC out of a 300+300VAC transformers.

Thyratrons need many amperes for the filaments. If my memory doesn't fail, 394A filament runs at 3.5A. The bigger 355As and 354As a whopping 15A!

Gianluca
Click to expand...

Can you show me how you wired these in a drawing? I'm interesting in using a set up like this also.
 
#37
sunrise, did you just want to use the thyratron as a simple diode, or were you after phase regulated control of output voltage because of ????

Phase regulation is going to introduce additional higher frequency ripple harmonics that you then have to filter out - unless you are actually wanting to modulate your music with higher frequency mains related harmonics?

You may encounter gross reverse recovery inefficiency and disturbance if you were aiming for a capacitor input type filter circuit.
 
#40
sunrise said:
thanks guys for any info...

i have found somewhere this schematic for half wave manually controled rectifier.......
the left transformer is clear - high voltage...
the one in the middle also - heating of the tube....
but the oneon the right is not very clear to me......what's he used for.....
and also - that variable capacitor - what is he used for and how to tune it - to what to tune it.....
Click to expand...

No, the left one is an ignition transformer, and the cap adjusts the moment when it ignites, i.e. near the 0V crossing.
 
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