Found in an American 1980s documentation, this circuit compares signals from two TTL sources, providing an output that depends on the frequency difference. The circuit can be used as a shield.
We obtained this circuit from the 1977 National Semiconductor FET Databook. The frequency depends only...
In this circuit, Motorola's Linear Interface ICs, R3 is used to compensate to high source...
The coil L2 has 64 turns of wire 28 or thinner wire in a 1 cm form coreless and L1 10 turns on L2....