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Update= lots of members have said this is not pracitcal, I know that. I just wan't to know how high current rated the diodes have to be in relaction to the input current
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
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Posts: 374
Thinking about the cascade in a simple way, it has to shift charges between two groups of capacitors which has to happen in one half cycle, so the current rating needs to be twice the desired output current. Another problem arises: as you're charging and discharging capacitors, the current waveform is strongly dependent on your driving waveform and may be a multiple of the output current. Plus, you're looking for the pulse SOA rating here. Why would anyone build a villard cascade / CW multiplier / Greinacher circuit (the latter invented it) for 10A anyway?
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
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>> for a vttc, of course!
in this case you should start with half or full bridge converter that is fed by 350..400V generated by a PFC boost converter which will involve a serious number of well-designed magnetic components such as storage chokes, a transformer and several filter chokes. You could as well buy a neon sign transformer but that wouldn't be the same, would it?
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
That's silly! :P If you knew how to use all that converter stuff, you could forget the vacuum tube and build a SSTC.
The time-honoured way of powering a VTTC is with the transformer, capacitor and diode salvaged from a microwave oven. You also need a RF bypass capacitor, to stop the RF from the tube oscillator going back into the power supply and destroying it.
Multiplying up 240V line voltage with a cascade is only practical for smaller, lower powered VTTCs using TV sweep tubes. (120V line is even worse.)
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
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Of course it is, sorry for that Building a regulated high voltage supply with more silicon than is in the glass envelop of a tube just doesn't make sense but I can think of no better way to get rid of the line frequency/harmonics. I tend to forget what 803 wanted. So how about, let's say, 10-15 toroid core transformers with their secondaries in parallel and their 240V primaries in a diode-split assembly
No when I ment 10 amps, Iment input. I want around 600 milamps in. THis is just making things simpler, when you double the voltage , thats a voltage multiplier to. So why can't you use multipliers all thw way? It wouldn't make things worse except higher voltage drop off and lower efciency. Any way, it makes things lighter and cheaper
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in a villard cascade do the diodes have to be rated of 1/2 the input current?
Building a regulated high voltage supply with more silicon than is in the glass envelop of a tube just doesn't make sense but I can think of no better way to get rid of the line frequency/harmonics. I tend to forget what 803 wanted. So how about, let's say, 10-15 toroid core transformers with their secondaries in parallel and their 240V primaries in a diode-split assembly 