Peak voltage detector schematic

Ignoramus20878 · 2005-11-29T20:29:41+00:00

I would very much like to make some sort of a "peak voltagedetector". A device that, when plugged into a circuit, after awhile, builds up an adequate representation of peak voltage. Thatwould be again for my IGBT inverter. That's for peak voltages under, say, 1 kV. I tried making one from just a cap and diode, but multimeters woulddischarge it too quickly and getting reliable readings is difficult.After reading the art of electronics, something like this comes tomind:Make a small capacitor charged by diode (and a series resistor tolimit current). After a while, voltage would build up there. Connect a voltage divider (say, 1 megohm and 1 kOhm in series). To thecap. That would be a 1:1001 divider. Connect that as input to some sort of FET based amplifier (that takesvoltage and does not require input current) that produces samevoltage, but at higher current. That would be the input ot a regularmultimeter.The multimeter reading would need to be multiplied by 1000 to get theactual voltage. Alternatively to all this, does anyone know if higher end multimeterslike Fluke 8050A (which I have) can measure voltage withoutdischarging the cap so much? I have one lying around somewhere.i

Nov 29, 2005 21 Replies

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Ignoramus5455 20 years ago

One more question, is the output of his opamp going to be enough to reliably read it with a multimeter? It looks like yes, but I want to double check. I really want to build a nice PVD.

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Ignoramus5455 20 years ago

Thanks. I printed out the datasheet and will read it on the train. I basically want to build something that would detect up to 2000v peak voltage, say.

Do you know if typical little resistors are protected up to that voltage? I have some from an assortment that I bought off ebay.

My plan is to make a circuit based on

- voltage divider -> diode -> capacitor -> opamp -> multimeter

maybe with 1000 times reduction in voltage read my multimeter.

So if I read 0.625 v on the multimeter, I know that there is 625 v peak voltage.

thanks.

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