This latched alarm uses a double relay for this purpose and can control higher power external loads like a siren. The circuit is from 1974 documentation and has a very low consumption.
In the figure we have the way to connect 6 solar cells in order to obtain higher voltage and...
This circuit has a maximum frequency of 10 kHz and a linearity better than 0.01%. The circuit is...
This circuit was obtained in a 1961 magazine, but it can be easily assembled today, as the...