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 got this circuit from Radio Electronics from July 1990. The circuit mimics the sound of the red...
This circuit regulates the output voltage of a 12 V source or other value, given by the zener. The...
These reset circuits when the power is turned on were found in an 80's EDN. The circuit also...