This circuit allows the activation of a remote telephone bell made with a common piezoelectric capsule. The circuit does not need power, as it is powered by the line call signal itself.
The circuit presented, from 2006, serves to control loads at a distance, robots, etc. It can be...
This circuit is given in two versions, having been found in a publication from the 90s. The second...
I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245....