Published by Philips in 1965 documentation, the sensor for this circuit is a common LDR. The transistors are general-purpose types from the time, only TR3 is a power type according to the load.
We found this circuit in an old documentation, using an operational of the time. The circuit...
This circuit shows how to use a 3-terminal voltage regulator as a low frequency oscillator by...
The circuit bellow uses two NPN transistor to drive heavy loads up to some amperes. The maximum...