quarantine continuity meter

A tiny DIY continuity tester that can be built at home using minimal supplies. Male-to-female jumper cables are used as probes.

The circuit is simply a coin cell battery (CR2032), an SMD resistor and LED and a two-pin-header in series. I used another two-pin header to mount the SMD LED. The resistor and LED should be roughly matched to the battery voltage. I am using a red SMD LED and a 499R resistor on this 3V battery.

The battery is connected to the rest of the circuit using small coils of copper enamel wire that press onto the two poles of the battery. Everything is housed in some cardboard that was recycled from packaging material. The header pins can be brought out through holes in the cardboard, so that the LED is visible and the probes can be conected on the outside. The coils are placed so that they come into contact with the battery when the cardboard is folded closed. Everything is held in place with simple household tape.