Found in 1968 Mullard documentation, this circuit uses period components. The transistors are matched pairs and the sensor is an Indian photocell of the time.
The LM567 is a PLL tone decoder that can also be used as a double oscillator as shown in the...
Originally designed to analyze the shape of light pulses from a flash for photographic...
This interesting control circuit was found in an Electronics Now from 1988. Through it we can...