This is the factory setting (National Semiconductor) of the TDA2006 as an audio amplifier. The circuit works with 24 V and the diodes can be 1N4148.
This circuit with LDR and neon lamp has its operating frequency given by the light. The circuit is from...
Found in American documentation from the 90s, this circuit can be used as a shield with the...
This tone recognizer circuit that relies on R5 and C1 was found in the December 1994 issue of...