This circuit was found in 1960s Radio Electronics. The circuit uses components from that time. The triac is according to the controlled load. The sensor is a common LDR.
Obtained from an English publication, this circuit actually needs a current limiting resistor,...
This circuit has its gain determined by the control DC voltage. The circuit is from a Radio...
This oscillator is a 1950s application of one of the first types of commercial transistors, the...