This LED diode test is suggested by the Texas Instruments optoelectronics manual. The transformer current can be between 50 mA and 300 mA and the voltage between 6 and 9 V.
This circuit is from Motorola's Linear Interface ICs of 1993. The circuit can be implemented with...
We find this circuit in an American 1980s documentation. It triggers an alarm in the event of a...
This circuit was obtained in a 70s American documentation. The integrated circuits of the time are...