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 ...

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 circuit has been designed for transistors to determine whether the pin is emitter, base or collector as well as the type if NPN or PNP polarity, and can also be used in testing diodes. 4011 – a ...

The CT20 is a two-part system consisting of a master continuity tester/transmitter and a two lead, bi-color (red/green) LED remote probe. The continuity tester/transmitter is used for local continuity ...