Designed for the audio track, this circuit was found in a Popular Electronics from the 90's. Other operational can be used and R7 can be 470 k. The frequency is 1 kHz.
The CK722 transistor used in this circuit is one of the first commercial types in the world. The...
This automatic dimmer for incandescent lamps was found in a European publication from the 1980s. The...
This traditional doubler configuration with the 555 can be found in other articles on the author’s site....