Electronic self-locking interlock switch circuit

Self-locking interlock switches are widely used in electrical appliances, and are generally mechanical. The disadvantages are: large size, easy to wear, large touch force, and low switching speed. Electronic switches can overcome the above shortcomings. one. Switch features. The core device of the switch is the quad operational amplifier LM324, which is cleverly designed so that each operational amplifier has two functions, a voltage comparator and a Schmitt trigger. The voltage has a wide applicable range and the gears can be designed arbitrarily. If a neutral gear is added, it can be used as a total reset. When used with digital circuits, the same power supply can be used. The input and output levels of the switch conform to the interface level of the digital circuit. Since the op amp The input impedance is high and the input current of the switch is small, so a touch switch can be used. Conductive rubber. Membrane switches can be used as buttons or driven by optical, electrical, magnetic and other conversion signals, and transistors can be used. SCR. Relays etc. two. Circuit principles. The circuit of each gear is the same, only three gears are shown in the picture. The resistor is selected according to the voltage to ensure reliable operation of the switch. Try to use a large resistance value. When the power is turned on, R1 and R2 divide the voltage to provide a high potential for the inverting terminal of each op amp, so that each op amp outputs a low potential. When any key is turned on, the non-inverting end of the corresponding op amp obtains a high potential, which is 1.4V higher than the inverting end (diode voltage drop), and the output becomes a high-break switch button. Due to the feedback of the voltage divider by R3 and R4, the potential of the non-inverting terminal is still higher than that of the inverting terminal, and the output terminal maintains a high potential. When another key is turned on, the circuit repeats the above process, and at the same time, through the two diodes D1. D2 makes the inverting terminal potential of all op amps higher than R3. The potential of the non-inverting terminal formed by the voltage division of R4, so the output terminal changes from high to low. In short, every time a button is pressed, only the op amp outputs a high level, and the rest are low. This is the self-locking interlocking function of the switch.