This series and parallel sensor circuit was found in Popular Electronics from the 1990s. Any SCR can be used and the supply voltage depends on the load.
This partial circuit that must be added to a preamplifier output transistor as in CB19186E...
This 4-competitor TTL speed game was obtained in a 1980s documentation, but can still be easily...
We find this circuit in an American publication of 1978. The integrated circuit is the CMOS 4013...