Found in old American documentation, this circuit is intended for the control of heating elements. The SCR must have current according to the controlled load. Transistors are from the time.
This circuit uses an unusual PLL, the 4046 CMOS. We found it in the October 1994 issue of...
This alarm circuit was found in a 1989 Poptronics, but all the components used are common, as the...
We found this circuit in a 1995 documentation. It can measure frequencies from 100 kHz to over 100 MHz...