Water level automatic controller production circuit

Circuit working principle: Figure a is the motor control part, Figure b is
the water level detection and electronic switch part. In Figure 1-22b, the transistor VT, resistor Shu,
R: and diode VD. Form a contactless electronic switch. The input terminal of VTl is connected to the control terminals S, M and D of
the water level detection element, that is, the three electrodes, through the compound contact K of the curse and the DC relay K.
Transistor VTz, resistor R:, capacitor and diode
VD2 form a voltage-dividing amplifier circuit with temperature compensation, which serves as an amplifier stage and
drives the DC relay K. Capacitor C2 and diode VD3 are the release circuit of K. They
absorb the back electromotive force generated when K loses power to protect the transistor VT2. VD4, VDs,
VD. It forms a bridge rectifier circuit with VD7, C2 is the filter capacitor, and T is the transformer. The main circuit
of the motor control circuit is composed of the three-phase knife switch S, the fuse FU, the main contact of the AC contactor KM and the three-phase asynchronous motor M.