This circuit is from a 1968 Electronic Design. The circuit uses transistors of the time that can be replaced with modern equivalents. More stages can be used to get higher tension.
In the figure we have the way to obtain an adjustable 1 to 10 mAconstant current source. The...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...
This alarm uses several sensors that directly trigger a sensitive relay. A larger relay can be...