I found this circuit somewhere, (I can't remember) to replace the 1.50 volt battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that is in p erfect condition but doesn't get used very often. This battery retrofit cir cuit takes power from the 6.30 volt filament transformer and is built aroun d an LM317. With a trim pot you set it for 1.55 volts and you never have to change a battery again. It also needs to occupy an area no larger than the battery presently does.
As much as I like keeping things original, I'm worried that the battery is going to leak and rot the inside of the unit. I was going to build the circ uit but it occurred to me that I should probably be concerned about the cur rent that the LM317 will be dissipating when the meter is used on the low o hms range. Does anyone have a feel for the size that an adequate sized heat sink should be in order to handle this? Thanks, Lenny