This small audio amplifier circuit in complementary symmetry was found in the 1974 Mullard Databook. The output pair can also be the BD135 and 136.
This circuit, for older machines, fires a second flash with the light received with the first, thus...
This circuit was found in a 90s Popular Electronics. The circuit indicates if a transmitter is working,...
Here is another project that is based on an astable multivibrator, in a demonstration of the...