This anti-theft circuit was found in a 1985 documentation. It uses common components that can still be found easily. The relay is 12 V and the circuit has timings of 3 minutes and 20 seconds.
This configuration is also valid for other operators and the formula for calculating the gain is...
This inductively coupled oscillator was found in an American documentation from the 90's. The...
This circuit was obtained from an Analog Devices manual from the 90's. The integrated circuit is...