This circuit was obtained in a documentation from the National Bureau of Standards of 1968. The circuit is of low current and the output can be changed to voltages between 2 and 30 V.
This dual adjustable power supply was found in the June 1990 issue of Radio Electronics magazine....
We found this simple alarm circuit in a 1986 documentation. The circuit uses sensors of the NA...
This circuit, from a 1973 documentation, can be made with BC549 transistors. The frequency depends on...