This monostable circuit was found in a European publication from the 70s, but it is perfectly up to date. We can use the BC548 and BC558 transistors which are the modern equivalents of those used in the original design. The activation time is given by the capacitor of 0.05 uF (47 nF) and the supply can be between 5 and 12 V. The circuit can be used as a shield.
