Insulation tester

[Nick]

I began this project about seven years ago and it has been laying about doing nothing for ages.
Inspired by a flee-market find it is back again.
It was going to be a range extender for an AVO 8/9.
It now has its own dial and I have started looking into the regulation for using lower test voltages.
The main unit has an SMPSU chip and LOPT from an old VGA screen.
The output voltage shot up with just 20 volts HT
It is the low end of the focus chain I need to find now.
That voltage needs taming big time.

This is a bit scary - What are you trying to achieve here?

For 17th Edition insulation testing you only need 500V or 1000V in exception cases (for higher voltage systems than domestic). What you seem to be building is a breakdown tester which could destructively test insulation - of course, once insulation has been tested to breakdown, it cannot be reused as it will no longer be to spec - there may well be carbon tracking etc.

I've spent a lot of time messing with HV - up to 500,000 V - Using a LOPT is fun, but difficult to control - if you are testing insulation, you need to control the parameters of that test pretty well in order to get meaningful results. Colour LOPTs can generate up to 25KV, B&W ones somewhat less (a few KV) - they are not current limited and can kill. Safety. Safety. Safety.

Finally, the inside of that box looks highly unsafe - the LOPT and HV side should be physically separated and isolated from the LV side of the circuit and preferably have an earthed screen. Special HV connectors and cable also need to be used...