This automatic brightness control that uses an LDR as a sensor, was found in American documentation from the 1980s. Resistors in series with LEDs depend on the desired current.
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...