Using the integrated circuit 723 we found this power supply in an article in the magazine Radio Electronics from August 1971. The transistor may be a BD136 equipped with a heat sink.
This interesting circuit, which can be used as an alarm, was found in a 1997 documentation. It...
In the figure we have the 4047 application-circuit which consists of the monostable version in...
With this circuit it is possible to excite direct current relays from an alternating signal,...