We found this circuit in an old documentation, but it is still current. General purpose transistors can be used, and the SCR can be the TIC106. The bell is a transducer with an oscillator (buzzer).
A touch of the sensor makes the load bistable (load) connected in Q1. For a BC548, a 6 V or 12 V...
With the use of an additional diode and a resistor, the configuration of the figure can be...
This circuit was found in documentation from the 1980s. The circuit uses several components of the...