In the figure we have a circuit of an analog computer published in the Radio Electronics magazine of June 1958. Accuracy depends on the components used, mainly the potentiometers.
This circuit from a Popular Electronics shows how to take the audio signal from a telephone line...
The coil of this transmitter has 4 coils of wire 26 or 28 in the form of 1 cm without core and on it...
In the figure we have another configuration of filter that uses the four Norton amplifiers of the...