Found in a 1967 Ferranti documentation, this circuit uses a LDR from that time as a sensor. Transistors can be replaced with modern equivalents.
The frequency depends on the coil and is not found in the original documentation but should be...
This is a device for those who need to show that they know how to use digital electronics but have...
Using an operational amplifier with FET, this circuit from a 1977 publication can generate...