This 50 Hz rejector or notch filter was found in a 1975 documentation. Other frequencies can be obtained by changing components. The filter uses a Wien network and must use a symmetrical power supply.
The modified Hartley oscillator, seen in figure 2, can generate signals ranging from 3 MHz to 10...
This circuit produces a high voltage (above 5,000 V) to ionize the air around a needle that acts...
Found in American documentation from the 90s, this circuit provides three timings given by the...