The next circuit diagram is to measure blood pressure by converting pressure into voltage.
It is said that the highest blood pressure and the lowest blood pressure are compared with the reference voltage, but I do not understand, so I ask.
Please explain the circuit analysis and implementation process.
Answer 2
The operation of the four circuits is simple.
First, in order to make the reference sensor voltage, I made 2.5V using parts that make LM335-2.5V and connected it to the pressure sensor.
The pressure sensor is mounted on a person's forearm. When you go to the hospital, this pressure sensor is installed on the part that wraps around your arm. Then you blow air into the tube that wraps around your arm, which temporarily disrupts the flow of blood in your arm. Because it’s a sin
Then, the pressure in the blood vessels increases at this time. Because the blood flows and the power to do it becomes stronger.
At this time, the value of the pressure sensor is read. Probably it will come out loud.
Then, if the air is drained, the blood will hardly flow through the blood vessels, and then it will flow like a sudden burst. If you measure the value of the pressure sensor at this time, this is the highest blood pressure.
Doctors are diagnosing by putting a stethoscope into the part around this arm and listening to the sound through their ears.
As time passes, the blood in the blood vessels normally flows and the signal to the pressure sensor gradually decreases. When you go to a certain point, it sounds almost constant, and the value at this time is the lowest blood pressure.
Therefore, in the above circuit, the first LMC662 is a circuit that makes the differential output of the pressure sensor into a single output, and its AC signal (i.e. blood flowing signal) is applied to the LM4558 via C1, and is 133 times higher by the resistance 15K and 2M. After amplification, it is applied to the next stage through 104,1S106.
This does not mean that all signals are amplified, but output after amplifying based on the level equivalent to 1/2 of the supply voltage by a 10K, 10K divided voltage across the 3rd terminal of 4558.
The output signal seems to be applied to the A/D port of the micom after a certain level of L358 is cut off.
It seems to be a little complicated and cluttered circuit, it could be simpler.
Answer 1
From the schematic, it seems that FPN07PG is a sensor that measures blood pressure.
The reference voltage is generated from U3 and supplied to the sensor, and the two arrows on the sensor measure the lowest blood pressure, one the lowest blood pressure, and the other.
Each measured voltage enters PORTs 2 and 3 of LMC662 and outputs the voltage difference between ports 2 and 3 to port 1, and the output signal is sent to the signal called "ADC0" and the input of LM4558. Loses. From the name of "ADC0", it seems to be input as CPU A/D CONVERTER PORT.
The signal sent to the LM4558 is output to port 1 of the LM4558 after the DC component is cut off from the capacitor and only the AC component is amplified by "2M/15K" times. The output signal is detected at D1 (1S106) and capacitor 104 and converted to DC.
The signal converted to DC is connected to port 3 of LM358, and the LM358 compares the voltage with port 2 and sends a HIGH or LOW signal to port 1, the output of LM358.
It seems that the signal is connected to PORTD5 of the CPU and the CPU judges the situation.
For example, if the difference between the lowest blood pressure and the highest blood pressure is greater than the set difference, it seems to be displayed as HIGH if it is small.
If the overall circuit and equipment characteristics are not known and judged only by what is shown in the circuit diagram, it is judged to operate as above.
I hope this helped.