We found this circuit in the April 1982 Radio Electronics magazine. It contains a good power stage whose transistor must be mounted on a good heat sink.
This circuit is intended to apply the music signal from a stereo to a telephone line for the...
This tachometer from a 1994 publication has a bargraph scale with the well-known LM3914 integrated...
This traditional triplier configuration with the 555 can be found in other articles on the...