The sensor is S1 in this alarm that we found in a Radio Electronics magazine from May 1971. Several sensors can be used in series. The SCR supports equivalents from the 106 series.
The purpose of this circuit is to eliminate RF picked up by a turntable. The circuit is from a...
This circuit synchronized by the power grid can be used as a shield. We found it in an 80's...
This is a very simple version in which we simply fit the jacks, plugs with red and green LEDs,...