On Thursday, March 20, 2014 12:16:03 AM UTC-4, wrote:
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 perfect condition but doesn't get used very often. This battery retrofit circuit takes power from the 6.30 volt filament transformer and is built around 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 circuit but it occurred to me that I should probably be concerned about the current that the LM317 will be dissipating when the meter is used on the low ohms range. Does anyone have a feel for the size that an adequate sized heat sink should be in order to handle this? Thanks, Lenny

Besides the things I've already mentioned regarding digital vs. analog, I've tried checking transistors and diodes with a digital, and I suppose that you can do it but perhaps it's because I've been doing this all my life with something like a 260, trying to do this with a digital drives me nuts. And Trevor you asked how you insulted me. You referred to my meter as a "piece of ****". You've never used it nor have you ever seen it. So where the hell did that come from? You may have your own opinions but there was no reason for that comment. Lenny