Medical ultrasonic nebulizer 2

The medical ultrasonic atomizer introduced in this example has functions such as mist volume adjustment, automatic liquid level detection, low liquid level automatic protection, and timing.
Circuit Working Principle
The medical ultrasonic atomizer circuit consists of a power supply circuit, a fog volume and liquid level detection control circuit, an ultrasonic oscillator and a fan motor M, as shown in Figure 9-111.

The power circuit consists of timer Q, fuses FU1, FU2, power transformer T, rectifier bridge stack UR, resistors Rl, R2, light-emitting diode VL and filter capacitor Cl.
The fog volume/liquid level detection control circuit is composed of resistor R3, potentiometers RPl, RP2, magnetic water level switch SA (composed of a float with magnetic ring and reed switch) and capacitor C2.
The ultrasonic oscillator consists of transistor V, resistors R4, R5, capacitors C2-C6, inductors Ll-L3, diode VD and ultrasonic transducer B.
After the timer Q is turned on, the AC 220V voltage is stepped down by T and rectified by UR, one line is current-limited and stepped down through the anus, and VL is lit; the other line is filtered by C2 and provides the fog volume/water level detection control circuit and ultrasonic oscillator. +48V working power supply.
The ultrasonic oscillator oscillates after being powered on, generating an ultrasonic oscillation signal with a frequency of 1.65MHz or 1.7MHz, driving B to generate high-frequency vibration to atomize the liquid medicine. The atomized liquid medicine is blown out from the duct opening by the fan.
Adjusting the resistance of RPl can change the base voltage of V, thereby changing the amplitude of the oscillation signal, thereby achieving the purpose of adjusting the amount of fog.
RP2 plays an auxiliary regulatory (fine-tuning) role.
When the liquid level in the atomizer reaches a certain height, the magnet installed in the float rises as the liquid level rises, causing the contacts of the reed switch SA to connect and the ultrasonic oscillator works; when the liquid level drops to a certain height When the float drops, the SA contact is disconnected and the ultrasonic oscillator stops working, which plays the role of automatic protection for low liquid level.
Component selection
Rl and R3-R5 all use 2W metal film resistors; R2 uses 1/4W metal film resistors.
Cl-C3 and C5 both use 1OOV CBB capacitors; C4 and C6 both use high-frequency ceramic capacitors.
RPl and RP2 use 2W synthetic carbon film potentiometers or multi-turn wire-wound potentiometers, and RP2 can also use variable resistors.
VD selects RFl04 type fast recovery diode.
VL uses φ3mm high-brightness light-emitting diodes.
V selects BU406 or SD35 high back-voltage silicon NPN transistor.
Ll uses a high-frequency choke, and L2 and L3 both use TDK color-coded inductors.
B selects 1.65MHz or 1.7MHz finished piezoelectric ultrasonic transducer.
T selects a 40W power transformer with a secondary voltage of 45-5OV.
M chooses AC 220V micro fan.
Q choose 0-60min mechanical timer.