This two-tone alarm siren was found in the January 1975 issue of Radio Electronics magazine. The power transistor can be changed and with it, Rx has values from 10 to 47-ohm.
This circuit was found in an English magazine from 1983, but it can be assembled with BC548. The...
This circuit tunes MW radios to apply the signal to a good audio amplifier. The circuit is from an...
The cascade connection of two flip-flops allows division by 4, as shown in the figure. Note that...