This circuit triggers an alarm in the event of a power failure. The circuit is from an 80's documentation, being powered by 9 V battery. The parts are common today.
A 3-input OR gate can be made with an LM3900 amplifier, as shown in the figure. The purpose of the...
This simple transistor circuit is from a 1950s publication. There were no LEDs at that time so an...
In the figure we have a TTL logic interfacing circuit as CMOS logic using a 6N139 optocoupler...