This circuit was obtained in a 1978 publication. The SCR may be the TIC106. What it does is act as a monostable that keeps the SCR fired for a time given by R1 and C1. In this way, when activating a bell with a relay by a touch, at the end of the time delay the SCR pulse short C2 deactivating the relay. Eventually R2 must be changed to obtain the desired operation.
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