We found this circuit in the April 1979 Radio Electronics magazine. Note the filter capacitor bank that can now be replaced by a single equivalent value capacitor.
The transistors of this circuit may be general purpose and the power supply comes from the TTL...
We found this circuit with the CMOS4046 in the August 1994 Electronics Now magazine. The circuit is...
This setting appears with variations at various points on this site. This is from a Motorola...