This simple but clever continuity tester sports two LEDs: RED LED = circuit resistance is < approx 10K, GREEN LED = circuit resistance <10Ω. It consumes approx 8mA from a 9V battery. When not ...

No multi-meter? For troubleshooting most household things, a continuity tester is extremely handy. And as it turns out, you can make your own from the dollar store for next to nothing. [Carlyn] sho… ...

Inside, a pager vibration motor is connected, vibrating when continuity is found. The circuit runs from a 1.5V AA battery which neatly fits inside the marker shell.