Found in a Popular Electronics from the 90's, this circuit detects the approach of objects by the reflection of the radiation emitted by the LED. The relay is a 12 V sensitive type.
We found this circuit in an Analog Devices documentation from the 90s. The circuit is based on a...
This circuit turns off a load after an interval of 8 to 80 seconds adjusted on the potentiometer. The...
Found elsewhere in this section, this circuit is from the April 1971 Radio Electronics magazine. Note...