This circuit was found in a 90's Electronic Design. The circuit can be adapted to use modern components. The power supply is made with 5 V which allows its use as a shield sensor.
This circuit was found in a 1973 publication. The SCR may be the TIC106 and must use a heat sink,...
This circuit is from the time when slide projects were used. We find it in a 90's Wels’ Think...
This circuit was found in a Radio Electronics Constructor, English magazine of April 1976; The...