300V AC source needed for multimeter calibration

[DrJoe]

I'm in the process of restoring an ancient Triplet Multimeter (model 60). I need a 300V AC source for calibration (60 Hz).
Any ideas for the most economical way to get there?

I was thinking about the voltage multiplier that Dave explained in the Uni-T UT513 Insulation tester teardown (episode #468) but I have no idea what diodes and capacitors to use in the circuit or if special precautions are needed as far as voltage isolation cut-outs on the circuit board.

A 120:300V transformer is about $50 and I was hoping to do it cheaper.

The only ac source I have besides direct mains is a signal generator that only does 10V peak to peak.

Thanks,
DrJoe

[BillWojo]

Does it really have to be 300VAC? Small 240 to 120VAC control transformers are cheap, look on ebay. Run it backwards with 120VAC in and you should get 240 out the other side.

BillWojo

[mij59]

I was thinking about the voltage multiplier that Dave explained in the Uni-T UT513 Insulation tester teardown (episode #468) but I have no idea what diodes and capacitors to use in the circuit or if special precautions are needed as far as voltage isolation cut-outs on the circuit board.

An isolation tester uses a dc voltage, so you'll have to convert it to a ac signal.