This 1-transistor circuit for currents up to 50 mA was found in the August 1974 Radio Electronics magazine. The transformer is 50 to 200 mA.
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...