This alarm circuit with NC sensors in series was taken from an article in Radio Electronics magazine from May 1971. The SCR can be any of the 106 series.
The circuit shown in figure 1 serves to control a servo motor with a current of up to 200 mA. The...
The L3 coil is what basically determines the resonant frequency, around 1 MHz, in this oscillator found...
This circuit was found in a 1973 Radio Elettronica magazine. The Italian magazine no longer...