Powering DMM off LM317 instead of 9V battery , but what voltage ?

[lordvader88]

I don't have a 9V adapter so I'm going to use a 12V SMPS wall-wort with an LM317 circuit (only for the DMM, not other circuits too) . Just wondering tho the likely lower voltage I can get away with feeding it. Its a Brymen869. The battery light kicks in at 6.5V when its just reading AC wall hum in my room. I've never measured the output of the DMM when its pushing out current. But I'm sure it doesn't need 9V all the time since batteries aren't usually there, and its less likely to fail over time.

[IanB]

Can you try that again, but in English?

[Daruosha]

If I understood correctly, you want to power your DMM with an external power supply instead of the internal batteries. And if this assumption is correct, it's a VERY bad idea to do it with a non-isolated power supply. In fact running a handheld DMM from any power source other than batteries would reduce the safety by a huge margin and in order to do it properly you have to consider lots of safety issues (true isolation from mains power, avoid sharing grounds in your DMM and the circuit which you measure and .... ).

Long story short: don't do it if you don't know how to do it.

[lordvader88]

Yeah I'm more asleep than I realize, and yeah I just looked it up and its a bad idea, no wonder I have seen a video of someone recommending it .

I did hook it up and run it up only tested a resistor and a capacitor. Oh well, I need a rechargeable 9V, and built a charger circuit, no problem.