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 ...

Testing for failure with a multimeter is only partially effective, whereas a dedicated optocoupler testing circuit provides ...

3V is sufficient to turn on any LED, but is within its reverse break down voltage rating (that is why I did not use the common 9V battery). Short circuit current is approx. 30mA. I used a 3V lithium ...

If you are using infrared (IR) hardware in an IoT, embedded, or mobile hardware project and are currently experiencing difficulties debugging IR communications, using one of the circuits shown below ...