How humidifiers work

At present, household humidifiers on the market generally use ultrasonic method to atomize water, and blow the atomized water vapor out of the shell through the fan to achieve the effect of humidifying the air. Its electrical schematic diagram is shown in the attached figure. After the mains passes through the switching power supply, two voltages of 36V and 12V are output. Among them, 36V supplies power to the water vapor atomization module and 12V supplies power to the fan. In the circuit, D1 and D2 are water shortage indicator and working indicator respectively; the reed switch is the liquid level detection switch; RT1 is the fog size adjustment potentiometer. 02 is the core and its peripheral circuit is the ultrasonic generating circuit.

　　1. Working principle of the diffuser

　　After the power is turned on, the switching power supply outputs 36V and 12V. When the water tank has not been placed on the base or there is a lack of water in the water tank, the magnet is away from the reed switch, the reed switch pops open, Ql is turned on, the water shortage indicator Dl is on, and the working indicator D2 is off; there is no voltage at the base of Q2, and the ultrasonic generating circuit does not vibrate. When a proper amount of water is added to the water tank, the magnet approaches the reed switch, the reed switch is attracted, and QI is cut off because its base becomes a high level. At the same time, D2 is on, Dl is off, and the current passes through the reed switch, and after being divided by R3 and R6, it is sent to the ultrasonic generating circuit through R5 and RT1. The ultrasonic generating circuit vibrates, thereby generating mist, which is blown out of the shell by the fan to achieve the effect of humidifying the indoor air.

　　2. Common fault troubleshooting

　　[Example 1] The atomized water vapor cannot be blown out of the shell.

　　Maintenance: Turn on the heater, plug in the power supply, and find that the fan does not rotate. After removing the fan, measure the output of the switch power supply 12V. If it is normal, the fan is judged to be broken. After replacing the fan, the fault is eliminated.

　　[Example 2] No response when power is turned on.

　　Maintenance: After the power supply is turned on, no output is measured for 36V and 12V, which indicates that the switching power supply is faulty. After disassembling the switching power supply for inspection, the rectifier part is blackened. After measurement, one of the rectifier diodes (1N4007) is damaged. After replacement, the fault is eliminated.

　　[Example 3] The water vapor atomization is very weak, and the adjustment knob does not work. 'Repair: After measurement, the output of 36V and 12V are normal, Q2 has no breakdown phenomenon, and the resistors and capacitors are not burned black. However, it was found that there was a lot of dirt in the water storage tank, and a layer of scale accumulated on the surface of the transducer and the bottom wall of the pool. After washing and cleaning thoroughly, the atomization effect returned to normal after power on.

　　Tip: In daily use, many humidifier failures are caused by scale. Therefore, the water storage tank and liquid level detection part of the humidifier should be cleaned frequently to prevent dirt deposition. If conditions permit, you can consider using pure water as the humidifier water.