This circuit was found in an American documentation of the 90s. Optical resources with the LDR as a lens can help in obtaining directivity and sensitivity.
The circuit used is the 4093 configured as an inverter in this application from Radio Electronics from...
We find this circuit in a 1977 technical documentation. The circuit generates signals in a wide...
In the figure we have a way to obtain a 15 V symmetrical source with a 30 V single winding...