Found in a European magazine from the 1980s, this circuit can amplify signals from 10 kHz up to over 220 MHz with good gain. MOSFET supports equivalents.
This is one of the many possible siren configurations for the 555 integrated circuit. We found it in...
This timer has a divider programmed by BCD switches. The circuit is from a Radio Electronics...
Passaje Alarm This locking circuit was found in a 1988 publication. It locks a relay when the...