YF-28DSP electric hot water bottle circuit household appliance circuit

YF-28 DSP electric hot water bottle circuit is shown in Figure 1-8. ST 1 is the anti-dry boil temperature switch, ST2 is the water boiling temperature control switch, ST3 is
the heat preservation control switch, and SB1 is the water boiling (boiling water) switch. SB2 is the water outlet switch.
    (1) Water boiling and heat preservation circuit 220V AC mains power through 5A fuse FU1. Normally closed temperature switches ST1, ST2, ST3 and
the drive coil of relay Kl form a circuit. Kl's Kl-l and Kl-2 sets of switches are turned off. When Kl-Z is closed, on the one hand, the EH1 water heater is powered
and the red light-emitting tube LEDI lights up to indicate the heating status; on the other hand, because Kl-2 is closed, the two ends of the insulation heater EH2 and VD5
are short-circuited and stop. When working, the yellow light-emitting tube LED2 of the heat preservation indicator light does not light up. As the water temperature rises,
ST3 is disconnected when the temperature reaches 75°C . Since relay Kl-l is already in the closed state, its drive coil current loop is maintained. EH1 continues to heat. When the water temperature
reaches 85℃, ST2 is disconnected, Kl loses power, KI-1 and Kl-2 are disconnected, EH1 stops heating water and LED1 goes out. At this time, the AC220V
mains power forms a loop through EH1, EH2, VD5, ST1, and FU1. That is, after EH1 and EH2 are connected in series, the resistance value of EH2 is
much , and the voltage drop makes the voltage at both ends of EH1 very low and the heat generation is small and the operation is Half-wave power supply, in heat preservation state. At this time, the yellow light-emitting tube LEDZ emits
light to indicate the heat preservation status. When the water temperature is lower than 85°C, ST2 is closed. When the water temperature is lower than 75 pC, ST3 is closed, Kl is powered on, and
the above process is repeated. '
    In the insulated state, what if the temperature of the water is lower? At this time, press SB1 and Kl will move. EH1 instantly heats water to boil quickly. ST1 is
the temperature switch to prevent dry burning, when the temperature of the bottle is higher than 110℃. ST1 is disconnected and the 220V power supply is cut off. Keep the thermos protected.
    (2) When the water outlet switch SB2 is pressed in the water outlet circuit, the 220V mains power is added to the circuit composed of VD1 ~ VD4 through the 5A fuse FU1, the normally closed temperature switch ST 1, EH1,
EH2, and the SB2 normally open contacts (closed at this time) At the input end of the bridge rectifier, EHl and EH2 act to reduce the voltage at this time
. The rectified voltage is filtered by c1 to form a DC voltage of about 12V, which supplies power to the water pump motor and will be pumped out permanently. ⅥⅪ is the protection
diode. When the voltage exceeds 14V, the VD6 zener is turned on to protect the motor; in addition, when the motor is damaged due to open circuit + due to
the zener breakdown of VD6, C. The voltage at both ends does not exceed 14V to prevent the voltage at both ends of C- from rising due to no-load output, causing breakdown or even
explosion of C.