Programmable LED indicator

The most popular currcnt indicator in electronics is almost certainly the Iight-emitting diode (LED) which is available in a number of colours (red, green, blue, yellow, as well as dual colours) and variations (round, square, flashing). Unfortunately, these virtually indestructible devices are often abused: terrainals cut too short, current too high, burnt by a soldering iron, and many others. Most of these abu ses maybe prevented by the circuit described here: it enables the LED indication to be adapted to the circuit you are working on (flashing or not flashing, red, green and so on).