Electrical – How to check continuity or shorting using arduino

arduinomultimeter

I was trying to build a multimeter using an arduino (just for learning purpose). I am able to measure voltages directly using analogRead() and for measuring currents I am using a o.o1ohm shunt resistor. However, I cannot figure ot how to built a circuit to check shorting (i.e the buzzer would beep if there is a short just like in a DMM). Can anyone help me please?

Thank you.

Best Answer

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. A simple pull-up resistor will form a potential divider with the DUT (device under test).

The voltage at the GPIO will be given by $$ V_{TP} = \frac {R_{DUT}}{R_{DUT}+R_1}$$

You should be able to work out the rest.

  • Change the resistor value if you want more or less sensitivity.
  • There is no protection on the input to this tester so make sure your DUT is unpowered before connecting up.
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