DAC controlled high voltage source

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Lebowski

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Hello folks,

I am currently designing and building a testing device which requires a controllable high DC voltage source (0 - 270V) @ max 75mA. I would like to control this circuit using a DA-convertor (0-5V) on a microcontroller. I do not have much experience with power electronics, and I don't seem to find a lot of information about this subject. Can anyone please point me in the right direction?

Kindly looking forward to your replies,

Lebowski
 

Hello there,

You can use High voltage Op-amp after DAC output. But high DC voltage source (0 - 270V) @ max 75mA that may be a big deal for you.


Best regards,
 

To get 270 VDC, you need 200V AC, so the obvious device to start with is a mains (230V) to 200 V transformer rated at 20 watts (270 X .075). This is very unusual device and may have to be made for you. The first alternative is to get a mains isolation transformer 230 in 230 out. But it is likely to be alot bigger and expesive then you really need (20 watts), another alternative is to have, say 4 mains to 50 v transformers (>5W each) and connect them in series to get your 200V. Another way would be to have a transformer to reduce the AC to 24 V, then another transformer wired the other way around to step it up again.
Frank
 

You could likely adapt this circuit to generate the output. You would make the upper voltage supply 275V and the bottom supply -5V for your 270V output. The op amp bias power circuit would need to be changed (upper resistor increased to 22kΩ and the bottom resistor and zener removed). Also the transistor ratings would need to be checked to insure that they could withstand the increased total voltage increase from 250V to 285V.

Edit: The above circuit has a inverting output. For a non-inverting output you could add an inverting op amp circuit with a gain of 1 in front of the input.
 
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