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.
This 1960s Japanese commercial AM radio uses 6 germanium transistors and is powered by 4...
This well-designed bistable circuit was found in a 1970s documentation. Transistors can be current...
This microamplifier was found in a Popular Electronics from June 1968. It is an experimental...