Found in a documentation from the 90's, this circuit uses only one integrated circuit. The resistors in series with the LEDs depend on the power that can be between 5 and 12 V.
This type of circuit is widely used in old cassette recorders and tape players, regulating the...
We found this circuit in an old documentation from the 70s, but it can be assembled with modern...
This circuit with transistors from a 1995 publication. The circuit is powered by a voltage taken...