We found this circuit with duty cycle adjustment in the May 1988 Radio Electronics magazine. The source must be symmetrical, and the frequency given by R3 and C1.
This circuit uses a CA3140, an operational amplifier with FETs in the input stages. Equivalent can be...
Found in a Popular Electronics from the 90s, this circuit has a configuration that has been widely...
This circuit was found in an American 80s circuit manual. The components used are unusual. The...