Three-phase motor forward and reverse control circuit made by NE555

The dotted box in the figure below is a control circuit made of three NE555s. The original control panel is connected to the control board through a printed four-wire film. The connection method of the three buttons is shown in the figure below. The three control signals can only be set in the same way. Here, the low level is valid. The AC 14V output by the original power transformer is rectified, filtered and stabilized to power the control circuit. IC1 forms a monostable circuit. After power is turned on, the 47kΩ pull-up resistors at pins (2) and (6) are connected to VCC, so that the voltage at this point is higher than 2/3VCC, and the circuit is in the 0 state. Relay J1 is not attracted, and the normally closed contact J1K provides 12V to IC2 and IC3. The green LED lights up, indicating that the operation can be performed. The original startup process is omitted, and the start button is set to the stop button. IC2 and IC3 each form a bistable circuit. After powering on, due to the pull-up and pull-down action of the 47kΩ resistors at pins (2) and (6), pin (2) is higher than 1/3VCC, and pin (6) is lower than 2/3VCC. Both ICs are in the 0 state. When the forward key is pressed, the (2) pin of IC2 is grounded, and the circuit is triggered to flip to state 1. Although the key is released and the voltage of the (2) pin becomes high again, the (6) pin is always kept below 2/3 VCC, and the circuit cannot flip and remains in state 1. The (3) pin outputs a high level to make J2 and J3 energize, and the J3K contact closes, supplying power to the AC contactor KM1 to make it energize. The three sets of contacts provide L1, L2, and L3 three-phase electricity to the motor, and the motor runs forward. After the 12 contacts J2K are attracted, the reset pin (4) of IC3 is converted from VCC to ground and locked in the reset state, so that IC3 cannot be triggered before the forward rotation stops, which plays an interlocking role. To change the direction of operation, the stop key must be pressed first. When the stop key is pressed, the (2) and (6) pins of IC1 are grounded, and the circuit is reversed, turning from state 0 to state 1. The (3) pin outputs a high level, and the red LED lights up, indicating that the operation stops. 11 are simultaneously energized, the normally closed contact opens, and the subsequent circuit loses power and resets. When the stop button is released, IC1 (2) and (6) pins return to high level, the circuit returns to state 0, J1 is released, and the subsequent circuit resumes power supply. At this time, the reverse button is pressed, IC3 reverses to state 1, J5 contacts connect to KM2 power supply, KM2 energizes and adds the inverted three-phase power to the motor, and the motor starts to reverse. At the same time, J4 contact J4K converts IC2's reset (4) pin from VCC to ground, and the forward button is invalid. The two red LEDs serve as forward and reverse indicator lights. This circuit uses three more 12V small relays than the original circuit, but the IC and circuit used are relatively simple. This circuit is also suitable for the forward and reverse control of motors of other equipment. If the controlled motor is powered by a single-phase capacitor inversion, forward and reverse control can also be achieved by changing the wiring of one end of the capacitor through two AC contactors.