We found this circuit in a Radio Electronics magazine from December 1969. The circuit uses a low-power MOSFET that is not very common today.
This circuit found in a European publication from the 1980s, is based on PLL 566. The frequencies...
The circuit shown, with the printed circuit board, was found in an article in the June 1990 issue...
In the figure we have a simple timer with two voltage comparators of the four of an LM339. The...