[R-390] OT: 30V regulator?

[Bob Camp]

Hi

The 30 volt setup in that meter is a *very* low current affair.  
Without a schematic I'm only guessing, but 50 ua is probably the  
maximum current draw. Most of the time the current draw is zero. A 9V  
battery and a capacitor based DC-DC converter would do a very nice  
job. Anything beyond that is going to pull *way* more current for the  
regulator than your total load.

If you never want to replace the battery again, take a look at a  
stack of lithium coin cells. At 3 volts each, a stack of 10 will do  
the trick. Lithiums last pretty much forever on the shelf ...

Bob
KB8TQ