This circuit with the NE602 was found in the February 1997 Electronics Now magazine. The NE602 integrated circuit is not very common these days.
The Motorola MOC501O optocoupler has a complete amplifier inside the sensor, enabling the...
This circuit is suggested by the Texas Instruments manual of linear applications of the 90's. The...
This circuit was found in the Radio Electronics magazine of May 1990. The supply voltage depends on...