We found this circuit in the March 1995 issue of Electronics Now magazine. The circuit has a frequency range determined by C1 and R3. The signal generated is square.
Using the 4001 integrated circuit, this latching relay can employ any general-purpose transistor. The...
This proximity relay circuit was found in the July 1990 Radio Electronics magazine. The supply...
This circuit is from a 1970 publication. The time constant is given by 1.3R x C where R is the...