Using a 4046 PLL we found this circuit in the December 1989 issue of Radio Electronics magazine. The circuit operates at 220kHz, but this frequency can be changed by changing C3.
E) This circuit uses a reversible double contact relay to obtain the trigger lock with the...
We found this circuit in a 1964 Electronic Design. Transistors can be modern general-purpose...
This circuit was found in a 1979 magazine. We can use any JFET like MPF102 or BF245. The relay is 12 V...