This circuit uses a wire potentiometer, but the current is much more intense in the control thanks to the 2N3055 which must be mounted on a heat sink.
This circuit is from a 1979 publication. The sensor consists of plates or screens that, when...
Found in an 80's documentation this circuit uses an integrated from the uncommon era today. Other...
This circuit was found in a Popular Electronics from the 90s. It uses a LASCR which is a photo-SCR...