We found this circuit in a 1996 publication. The circuit uses components that are still common. The timing depends on C1, which can be changed, and the triac can be of any type.
A ring and pendulum of stripped wires form the sensor for this alarm. Once triggered, to reset, you...
Designed for the audio track, this circuit was found in a Popular Electronics from the 90's. Other...
An interesting basic circuit for projects is shown in the figure. It consists of a digital...