Found in na 1970 EDN this circuit has a parallel regulation providing a symmetrical output of 15 V. The transistors are from that time.
This setting appears with variations at various points on this site. This is from a Motorola...
This circuit emits an audible signal when the mains voltage ceases. The circuit is from a 1973...
The figure shows how to control the counting of a 4017 with a start and stop switch. | Clique na...