[R-390] OT: 30V regulator?

[Bill Hawkins]

There's a lot of talk about voltage, but not about current. Both
are required to pick a regulator.

I've used a Triplett 630 NA for as long as I could afford a good
meter. I value its portability, and would not think of tying it
to a line cord.

The 30 volt source draws microamps, easily done with a zener diode.
That's what the zero ohms adjustment is for. You can't do insulation
resistance without it. You can build a DC/DC converter for 1.5 to
30 volts at low current with a few parts. But how are you going to
turn off the 30 volt multivibrator when it's not needed?

The 1.5 volt source is another matter. It draws hundreds of milliamps
on the X1 scale. Really does seem easier to change batteries than to
remove the instrument's portability. Test lead resistance matters at
those currents.

Please excuse this humble opinion if it conflicts with your own
faulty reasoning.

Bill Hawkins