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).
This circuit activates an output, which can be a lock, only when a card containing the programmed code...
This circuit was found in Popular Electronics from 1993. The 1458 consists of a double 555. The...
This is a Serial In - Parallel Out or Serial Out [SIPO or SISO] shift register using the...