This circuit was found in a 1967 RCA documentation. The components are of the time. The circuit limits the current to 50 mA when the battery is fully charged.
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...