We found this active crossover in a Radio Electronics magazine from June 1961. Note the different adjustment ranges. The signal must be applied to the amplifier input.
This circuit can generate signals from 100 kHz to 50 MHz depending on the crystal and the...
The circuit in the figure represents a typical application of a phototransistor exciting a relay...
Found in Philips documentation from 1968 this circuit operates at frequencies up to 10 MHz with 76...