is ohmmeter safe

I soldered a header strip onto a esp32 for a streaming speaker project and it doesn't work. I want to check if I joined any of the pads together.

It seems that 1.5v is typical voltage for an ohmmeter. Is it safe to test for joins or could I fry the esp32? Should ground be connected on the esp32?


It's safe if you power down first.

1.5V at what current ? (uA?)

It is inversely proportional to the range. We are (usually) referring to a digital multimeter which generally measures using an actual 200 mV scale which means it will not "see" a silicon semiconductor junction except on the "diode test" setting which applies about 3 V but measures only to 2 - a LED will generally light up but not register.

So for 200 mV, 200 Ohms means a 1 mA current, for 2 kΩ it would be 100 µA and so on.

You would be more likely to damage it with ESD from probing then the meter. Wear proper grounding equipment and follow appropriate practices. Is 1.5V typical? No ohm measurements are a voltage measurement across the unknown resistor with a known current. I have several ohm meters and they are all different as far as the voltage from there internal current source.

I usually use a 5-30X magnification lense to visually inspect my small soldering, and a small flat screwdriver/needle/smallest mill for dremel to scrape between the leads if I'm unsure, if its really close you can measure just to be extra safe, next time do it before you turn it on for the first time

Resistance & voltage measurements ARE SAFE. If you measure resistance with the circuit powered-up you'll get an invalid reading and you might temporarily interrupt proper circuit operation but you won't permanently damage anything. I don't think I've ever seen it affect circuit operation, but theoretically it could happen. And, usually the reason you're measuring resistance in a circuit is because something isn't working...

Current measurements are where things get "dangerous". An ammeter is essentially a short-circuit so if you don't connect it properly you can short-out stuff and/or blow a fuse in the meter. That's why meters often have a separate current-measurement connection... So you are less-likely to accidentally have the meter in current-measurement mode.

....And if fact, current measurements (with a multimeter) are rare, and it's a pain because you have to break the circuit and insert the meter in series... I measure voltage & resistance "every day" at work but I can't remember the last time I measured current. But I do " cheat" because my bench power supply displays voltage & current.

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.