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Which OP is using?

Control and Amplify High Voltages Effectively and Safely with the Right High Voltage Op Amp

Hi Miguel,

This is my latest design. It's been something I've wanted to build for my 576 for about a year so I could draw a complete set of characteristic curves for vacuum tubes with a large cutoff voltage. The ADHV4702-1 high voltage op amp makes it very straightforward to generate the necessary negative grid voltage to drive tubes to cutoff. Gain is fixed at 10x so any step adjustments are made directly on the curve tracer. The only trouble with the ADHV4702-1 is that it's a QFN package, so it's a bit of a pain to solder.

I'd be happy to hear any feedback, other features that might prove useful, or applications it would be appropriate for. The current design is pretty application specific and the layout of the banana jack interconnects are for easy mating to the 576 and 577. The +0/-200v output doesn't lend itself to many other applications, but it could prove useful in the right situation. It can happily output 20ma @ 200v continuously. I suppose it could be useful as a negative bias generator when breadboarding or repairing vacuum tube circuits...

-Chris

It is a nice design. I like the compactness of it. I just figured out the Step Gen output and External input "trick" this past week. I wonder if the Tek engineers had this multiplier in mind when they added those jacks? It sure makes it simpler to hook up an external multiplier.

I like the one I made based upon ChuckA's design (I admit I am biased : ) ) as I can leave it hooked in and select "0" multiplication (as well as 50). Though the one I built goes to "only" -150V. I also prefer a linear power supply over a switcher and a wall wart supply.

Dave

My first batch of 10 sold out on eBay. Thank you to anyone/everyone who purchased a unit. I have built another 10 and renewed the listing:

If anyone from this group were to be interested in one, I'd be happy to give a 10% discount. Feel to reach out to me directly as well and we can bypass the eBay fees and sales tax.

-Chris