(Sorry, Baidu limits the ability to upload pictures here) Let me analyze it! A set of LM393 input has two phases, and four trimpots are used to adjust the center voltage of the LM393+/_ input terminal. For example, if the + positive potential input connection method is used, the +/- potential input terminal must be connected, and the input - The two trimmer potentiometers can be 10-30K, and two 10-30K potentiometers are also connected to the input + positive phase. For safety reasons, a 5K series resistor can be connected to each end of the four sets of potentiometers. , as the limit adjustment is too biased, causing the input terminal current value to be too large to burn the LM393. According to your requirement, if it is lower than 13V, it will automatically output 5V (connected to a three-terminal 7805 voltage regulator), then the working voltage of the circuit design should be 6V ~ 9V for stability! Sampling 12.9V is only used as a reference voltage. For example, using the voltage equalization method working mode, adjust the bias voltage division bias of the two potentiometers to 12.9V as the sampling comparison voltage value. The chip will automatically compare the potential ratio difference for identification. output. Adjust the four potentiometers so that the positive and negative phases of LM393 are at the critical point lower than 12.9V. With this 12.9V reference voltage, the LM393 voltage comparator will respond when the voltage is lower than 13V. The LM393 logic voltage comparator will respond to the output at the output end. High potential or low level (this change in high and low potential values ??can be used as a starting voltage signal to drive the 5V power supply output). The output end can also be connected to one of the CD4069 six inverters for high and low logic potential conversion. of. If you add a first-level medium-power transistor, you can drive the electromagnetic relay switch and use it as a power switch to control high-power equipment. You can also use a high-power integrated built-in photoelectric thyristor switch to replace the electromagnetic relay switch with low-speed response to mechanical opening and closing sounds.
(All principle introductions are based on experiments! Theoretically feasible, but they must be verified in practice! Only then can they be put into the real world and applied freely)
2018-6 —18 GZ—jk