This special effect doorbell circuit was found in the January 1984 issue of Radio Electronics magazine. The components are quite common and transistors such as the BC548 and BC558 can be used.
The basic idea of the circuit shown in the figure is to increase the brightness of an ordinary...
With the appropriate choice of C1 and C2 it is possible to divide the frequency of a rectangular 3 V...
This circuit was published in a 1979 magazine, but it can still be easily assembled as the...