If you’ve worked on a project with small LEDs, you know the frustration of determining their polarity. This ingenious LED Probe from [David] packs a lot of useful features into a simple, ...

This circuit can be used to test up to three LEDs at once, connected in series. You can easily increase that number by using a higher supply voltage. If you do so, you should allow 2.7 V for each ...

The simple Diode and LED Tester presented here costs under £5 to build (including all components, the battery and a cheap case) and will indicate the polarity of almost all types of LED and other ...