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.
This circuit was found in an American documentation from 1970. We can increase the number of...
The presented circuit allows to control the valve of a tap. The positioning of the emitter and the...
I found this circuit in an old British magazine from 1976. It is possible to test operational...