Views: 13 Author: Site Editor Publish Time: 2021-03-23 Origin: Site
Ultrasonic humidifier sensor circuit composed of ultrasonic transducers
The figure below is an ultrasonic humidifier sensor circuit composed of an piezoelectric ultrasonic transducer, which is suitable for humidifying the air in the room.
1. Circuit composition
The circuit shown in the figure above is mainly composed of an ultrasonic oscillator composed of VTi and its peripheral components. SL is a reed switch magnetic sensor, which together with the magnetic float of N-S polarity forms a water level control switch. B is an ultrasonic sensor.
2. Power supply circuit
The 220V AC voltage is added to the power indicator H through the power switch SA1, the AC fuse FU1. The mist exhaust fan motor M and the power transformer T primary. After the 45V AC low voltage output from the T secondary is bridge rectified by VDi～VD4 and filtered by C1, the obtained DC voltage of about 50V is provided to the subsequent stage circuit as a working power supply. The maximum operating current circuit of ultrasonic transducer distance measurement is about 530mA.
3. Ultrasonic oscillator circuit
The ultrasonic oscillation circuit is composed of VTi, Li, L2, etc., and the oscillation frequency is the same as the natural resonance frequency of the piezoelectric ultrasonic distance transducer B. ultrasonic transducer B is both a resonant element and a circuit load. RPi is a potentiometer for adjusting the amount of fog. RP2 is an auxiliary trimming potentiometer. Adjusting RPi can change the DC bias voltage of VTi, and the oscillation output amplitude can be adjusted within a certain range. The greater the amplitude, the greater the amount of fog produced.
4. circuit of ultrasonic water level control
The water level control switch composed of SL and N-S magnetic float is used to control the water level. The magnetic float moves up and down with the water level in the container. When the water level drops to a certain level, the relative distance increases, SL loses magnetism and disconnects, and VTi stops vibrating. At this time, water should be added to the container.
