Medical infusion alarm circuit

When patients are receiving infusion treatment in the hospital, they need to always pay attention to the amount of medicine in the bottle to prevent blood from returning after the medicine is dripped and not receiving timely treatment. This
circuit can be used to promptly remind the attendant or the patient to notify the nurse when the medicine in the bottle is finished dripping.
    Working principle: The infusion tube is a transparent plastic tube. When there is no medicine in the tube, the light is only in the tube wall, and only a small part of the light escapes;
when there is medicine in the tube, its cross section is equivalent to the combination of two cylindrical convex lenses, not only It can pass through and gather into a bunch, converting this changing light signal
into an electrical signal. Through the control circuit, an alarm can be issued without any medicine, as shown in the figure.
    LED1 is used as the light source for power indication and photoelectric detection. ICla, VD1, Rz, R3, cl form a Schmitt trigger circuit, IClb, Rs,
Ro, Cz, G are multivibrators, LED2 is used as a light alarm, R4. Wind, VT and music integrated block IC2, piezoelectric film sound alarm. Sl is
the power switch, and S2 is designed to only use light to alarm to prevent it from affecting other patients late at night. When there is medicine in the infusion tube, the power supply passes through VD1 to make the ② and
⑥ pins of ICla at high level, the output terminal ⑤ pin at low level, the ⑩ pin of IClb is reset and does not oscillate, and LED2 does not emit light. At the same time. The VT base is also at low level
, VT is cut off, IC2 cannot get power , and the piezoelectric film does not make sound. When there is no medicine in the infusion tube, the patient will know
that the medicine is used up by the flashing lights and music .
  From the time of alarm to the time when the medicine in the tube is completely dripped, it takes more than 2 minutes to notify the nurse.