This is a different circuit for a component from the past, the zirconium arc lamp used in projectors. The circuit is from an August 1972 Radio Electronics magazine.
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...