This circuit is from Mullard documentation from 1969. Transistors support current equivalents. Output transistors must be mounted on heat sinks.
The phototransistor of this alarm can be of any type. The relay must be sensitive type according...
This circuit was adapted from a 1995 Electronics Now magazine. He shows how to implement a type of...
This alarm circuit is from a 1987 publication, however the components used are still modern. The...