This General Electric circuit produces pulses of light only when light stops shining on the sensor. Equivalent SCRs can be used and the trigger adjustment is done in a trimpot. The maximum load is 40W.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...