AMB Laboratories DIY Audio

[VGH]

Hi everyone,

I'm planning to do some BJTs matching.
Would it be fine to use a new 12V 23A battery (the one which is often used in DMMs)
as a power source?

Ta

[amb]

Sure, any 12V DC source (that could supply a few mAs without significant voltage drop) will work. Note that the 23A battery typically has only 55mAH capacity so it might drain down if you are trying to match a lot of devices.

[VGH]

Note that the 23A battery typically has only 55mAH capacity so it might drain down if you are trying to match a lot of devices.

That is OK, I have a few of those batteries

A bit off-topic:
Ti, I have one of those cheap DMMs. It works fine from my point of view (all measurements make sense) but it drains a new battery in about 3 minutes. It happened from day one (should’ve returned one, but didn’t have a chance). As I understand, there is a short somewhere? Any chance me fixing it without having much knowledge in electronics in general? I’m just a bit curious..

[amb]

A bit off-topic:
Ti, I have one of those cheap DMMs. It works fine from my point of view (all measurements make sense) but it drains a new battery in about 3 minutes. It happened from day one (should’ve returned one, but didn’t have a chance). As I understand, there is a short somewhere? Any chance me fixing it without having much knowledge in electronics in general? I’m just a bit curious..

Do you have another DMM to check this one for a partial short at the battery? You can also try to measure its current draw from the battery. Since everything is working, it would seem to be it's just a case of bad design (circuit draws too nuch current for the type if battery used).

[VGH]

Do you have another DMM to check this one for a partial short at the battery? You can also try to measure its current draw from the battery.

Yes, I've got a couple of, again, cheap ones. There is zero continuity between battery pads.
I tried to measure the current draw. In 200 mili-amp scale I got a reading of 0.03-0.04.
(tried to measure resistance with DMM in question at the same time, the reading remained the same)
In 2000 micro-amp scale I got nothing. Weird
After these checks the battery votage dropped from 11.9V to 11.3V