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.
With this circuit it is possible to control an operational amplifier so that it switches an input...
This circuit consists of a traditional amplifier version with complementary output using BD series...
This circuit was obtained from a Texas Instruments 1985 document. The circuit is powered by 1.5 V...