I am trying to build a board to sense circuit voltage relative to ground at different points on a breadboard. I would want the board to work regardless of configuration of the circuit. The only exception would be the location of GND, which would be the same always.
There are two ways I was thinking about doing this:
- Voltmeter Modules:
My first idea was to get either a 2 terminal or 3 terminal voltmeter. I believe 3 terminal is less invasive to the circuit, but please correct me if I am wrong. My thoughts were that this would need to be powered externally so that it wouldn't effect the voltage within the circuit, whereas the 2 terminal voltmeter is actually using some of the voltage to power itself? Also I was assuming that the 3 terminal voltmeter would not have an effect on the circuit even if it was attached to a common ground within the circuit. Anyways I was wondering if you could verify these assumptions and offer some advice on the best one to use. Or let me know if this is a terrible idea (aside from the fact that is would be space intensive with all the voltmeters) :).
- Arduino Voltage Reading
My second idea was to use an Arduino and a multiplexer to sense the voltage within the system. Again I wasn't sure what effect the Arduino would have on the system if any if it is constantly attached and sometimes reading? The voltage I could sense would be based on the resistors I use. I then could use the Arduino to do something with the signals to make them visible to the user.
If you have any feedback on my questions, the solution you think would be the best, or alternative solutions, I would love to hear it!