This reinforcing stages from a 1960s documentation. No information is given about the transformer and the transistor admits equivalents.
Found in Popular Electronics from the 90s, this circuit aims to drive a solar panel, constantly changing...
This circuit triggers an LM380 oscillator, producing an audio tone with light falling on the LDR....
This circuit was found in a 1967 American documentation. The switching diode (tunnel) used is an...