We know that LED is a two terminal semiconductor device. It is used in most of the electronic circuits as a sign or visual representation to the normal human to know that circuit is working properly.

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 ...

High-brightness LEDs, with independent delay and duration, find use in a visual-inspection application. This circuit is not complex, but it saved the day in an application involving visual inspection ...