Physiotherapy ventilator circuit

Physiotherapy ventilators used clinically provide continuous oxygen to the patient's nasal cavity, which does not conform to the tracheal breathing rules during breathing, and the patient
will feel uncomfortable. The medical physiotherapy ventilator controller introduced in this example can automatically start the motor when the patient inhales, and automatically cut off
the motor transistor power when the patient exhales, which is both energy-saving and practical.
    The medical physiotherapy ventilator controller circuit consists of an astable oscillator, a control circuit and a power supply circuit, as shown in the figure. The astable oscillator
circuit is composed of resistors R, R2, potentiometer RP, capacitors C3, C4 and time base integrated circuit IC1. The control circuit is composed of resistor wind
~ wind, transistors VT1, VT2, diode VD5 and relay K. After the AC 220V voltage is stepped down by T, rectified by VD1~VD4, filtered by CI and stabilized by IC2, it provides +9V working power
    for the astable oscillator and control circuit .     After the astable oscillator is powered on, its ③ pin outputs an oscillation pulse signal with a frequency of 25.40Hz, causing VT1 and VT2 to conduct intermittently, and K and M to work intermittently. When the ③ pin of IC1 outputs a high level, VTI and VT2 are saturated and conductive, K is powered on and closed, its normally open contact is connected, and the motor M of the physical therapy ventilator is energized to work; when the ③ pin of IC1 outputs a low level, VT1 And VT2 is cut off, K is released, and M stops working after power off.     Adjusting the resistance of RP can change the oscillation frequency of the astable oscillator, thereby changing the operating frequency of the ventilator (it can be adjusted according to the needs of the patient during use ).