This circuit was found in a Signetics documentation from the 1980s. Next to the figure are the waveforms of the generated signals. The transistor admits equivalent.
This alarm, from a 1996 magazine, can be fitted with two BC548s in the original configuration...
Using only one general purpose transistor this circuit is powered by batteries. The lamp of the...
Can be used as a shield, this old American documentation circuit offers digitally selected...