Abstract: A security memory having a transistor oscillator with feedback, a power supply input, a control input, and an a.c. output as well as an amplifier. This memory designed in accordance with relay security standards, is of the negative control type, which stores the disappearance of a logic signal which is a function of at least one logic variable. To this end its control input is energized with a voltage whose absolute value is smaller than that of the supply voltage of the oscillator and is connected to the collector of the transistor via a diode, which collector in its turn is connected to a capacitor via a first transformer winding, which capacitor starts and sustains the oscillation.