This circuit for a simple alarm system was suggested in an article in Electronics Now magazine. The circuit has a small power stage that can be changed.
This circuit was obtained in the 1990 Motorola Linear Databook. The circuit uses a 139 series...
We found this circuit in an English publication from 1980, but it can be assembled with BC548...
The circuit shown in the figure has a very high switching speed and can work with currents up to...