This circuit was found in an American 1980s documentation. The transistorized step is the receiver's last IF and the diode is the receiver's existing detector.
A touch in this circuit turns-on the lamp or the relay. Power supply is according the lamp or...
Found in a Popular Electronics from the 90's, this circuit uses integrated from that time, today...
This isolated shield for triac was found in old European documentation. The resistor R1, in fact,...