This 6-tube two-channel amplifier was found in an American documentation from 1947. The circuit is two-channel with a separation of bass and treble.
A binary counter until 2" or a divide-by-the same value can be built by cascading n 4013...
We can control the frequency of an oscillator from digital circuits or from the output of a...
Found on Popular Electronics this circuit has variations found throughout this site and section....