[John L Stewart]

Here ya are Patrick, a constant voltage PS that can be varied over a range of 500 to 2500 volts. I will leave it to you to come up with an amplifier suitable to make use of this beast!

Again, this is one of my efforts before 1965. Not much new here, all analogue regulated power supplies are essentially the same, whether CV or CC.

They all need some kind of reference, a gas tube, zener & some folks have used Hg batteries. Then some kind of resistive network to sample the output. A comparison is made to the reference, then amplified by vacuum, germanium or silicon. The amplified error controls a passer element. And that too can be vacuum, germanium or silicon. Or a hybrid design using a combination of these. All depends on what the end result needs to be. And how many $$$$ are available.

The design elements are no different than an audio FB amplifier. Only the controlled variable is different.

This one used 3x 813 as the passer. The main amplifier is very much straight forward, 12AX7 differential comparator, 12AU7 amplifier & EL 360 for a very large voltage shift.

The error amp can be on either the +ve or –ve lead. But for most CV tube work it is preferable to have the error amp on the –ve lead. That creates a problem for HV applications as it does here. That last stage needs something like the EL360 that can handle very high voltages reliably.

Much easier with SS since there are both PNP & NPN devices. So the error amp can be on the +ve or –ve lead, no problem.

For the tube CC supply the error amp can be put on the +ve lead, no problem. The –ve lead is simply brought out separately to the load terminal. One of the projects I worked on used a CC supply to run a 2500 Watt Philips magnetron. I designed & built that one too. It was good for 4500 volts at One Amp.

The AC to DC conversion uses a Hammond autotransformer followed by a Hammond transformer. The rectifier is a full bridge of 12 Philips PH103s & 12 resistors of 470K in parallel. Followed by an oil filled cap of 2 microF, 3KV.

These daze SS makes things easier, but brings a lot of complexity with it.

Cheers to all, John