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.
This circuit was found in an 80's documentation using an NE5514, operating at the time. The font...
This circuit generates sinusoidal signals between 300 and 3000 Hz. We find a 303 Circuits from the 90's....
This circuit from a 2003 documentation, has a protection system that disarms the power supply if...