Electronic timer safety circuit - introduces delay between application of voltage and control of device to avoid transient effects during switching

摘要

The electronic timer is designed to be insented between a direct current supply source and a control element so as to effect a delay between the application of voltage and the control of the element. The timer comprises a field transistor (1) where source (2) and drain are respectively connected to one of the terminals of the supply (3) by a capacitor (4) and by a load (8). The other supply terminal (5) is connected to the source of the same transistor by a resistance (6) and to its grid by an alternating signal source (10). A circuit is provided for detecting in the load the amplified alternating signal which is used as the control signal for the control element. The safety device may be used in the field of miming for the control of switching to eliminate the effect of transient currents due to contacts bouncing.