Homemade intermittent operation control device for electric agitator

Electric agitators with a power of less than 20W are often used in chemical and light industrial enterprises' laboratory and testing departments to stir materials.

The operation of the agitator often requires intermittent circulation, which is very inconvenient if controlled manually.

A control device as shown in the attached figure can be set up to make the operation of the agitator meet the above requirements, that is, it can automatically power off after running for a period of time, and can automatically power on again after being powered off for a period of time. The power-on and power-off times can be adjusted independently without affecting each other, which is very convenient to use.

NE555 and its peripheral components form an astable circuit. The high-low switching time of the NE555 output terminal (pin ③) is determined by the charging and discharging time of capacitor Cl.

That is, the charging and discharging time of C1 is the power-on and power-off time of the electric stirrer M, so the timing and automatic operation of M can be realized by adjusting the charging and discharging time of C1.

When the NE555's pin ③ outputs a high level, relay K is energized and closed, M is powered on and operates, and the light-emitting diode VD4 (green) lights up. When the NE555's pin ③ outputs a low level, K loses power (releases), M stops running, VD4 (green) turns off, and the light-emitting diode VD5 (red) lights up.

Potentiometer RP1 is used to adjust the charging time of C1, and potentiometer RP2 is used to adjust the discharging time of Cl. The maximum charging and discharging time of C1 is about 16 minutes. If you want to extend the time, you can increase the capacity of C1 appropriately.

M can use JB90-D powerful electric stirrer, the working voltage is AC 220V, the power is 90W. Cl uses high-quality tantalum electrolytic capacitors to reduce leakage current and ensure accurate timing.

Adjust the resistance values ​​of RP1 and RP2 as needed, turn on the power switch S, and M will automatically operate according to the set on and off time cycle.