This alarm siren circuit has a latch. We found it in an article in the January 1975 Radio Electronics magazine. Note the power given by Rx and the speaker. It can be increased by changing Q1.
This circuit was obtained from an old publication from 1974 but can still be assembled with some...
This level matrix display was found in a 1994 documentation, but it can still be assembled, as the...
This circuit can be implemented with any triac of the TIC series and the lamp must be...