I have a control card where two pins can be shorted with a push button to trigger an action (5V can be measured between the two pins.)
- If I briefly short the pins with a jumper, the action is triggered as expected
- If I short the pins with a current-meter: nothing happens. By that I mean that I'm trying to measure the current between the two pins. I would expect the current meter to short the circuit, trigger a current and measure it.
My question: is that because the current-meter has too big of an internal resistance, or is it something else ? I reckon the approach is pretty naive but it got me curious now.
Background of why I'm doing this: I intend to remotely control the action using an Arduino. My idea is to use an optocoupler that acts as a push button (and keep both circuits isolated.) Then I wondered if I would need a resistor to avoid frying the optocoupler's transistor so I tried to measure a current. Apparently it doesn't work.
Also, should I be worried that my optocoupler will also have too big of a resistance to make the circuit work?
EDIT: I feel very stupid, but I think my multimeter is simply broken :/ It does measure voltages, but setting it to current even fails to measure a current through a simple resistor.