Blood pressure gauge electronic auxiliary meter, Electronic Blood Pressure Monitor
Keywords: sphygmomanometer electronic auxiliary meter
With the improvement of living standards, people's health care awareness is constantly increasing, often measurement of blood pressure is a health care, one of the main means of disease. At present, although there are already digital electronic blood pressure gauges, the price is high, the measurement error is relatively large, the most accurate is the traditional desktop hydraulic sphygmometer, the pointer blood pressure. These two sphygmomanometers (table) account for more than 90% of the current social ownership, and it is a major appliance for doctors to measure blood pressure for patients. The home's own has a lot. However, this sphygmomanometer requires a stethoscope to assisted blood pressure, and there must be certain measurement techniques, especially the judgment of diastolic pressure (commonly known as low pressure), and the human error factor is large. This article describes an electronic auxiliary meter for electronic enthusiasts. The auxiliary measuring device can make the measurement of blood pressure, not only replaced the stethoscope, but also observe the blood pressure value at the same time. Make people who don't understand measuring skills can also measure blood pressure. Working principle: Circuit As shown in Figure 1, the measuring device consists of acoustic wave acquisition, voltage amplification, low pass filter, waveform conversion, voltage detection, and acoustic display circuit.
HTD1 will detect the detected pulse signal to send V1, here, V1 enactment transform. The micro-sound wave signal voltage of high internal resistance is converted to a lower impedance output, coupled to IC1 via C1, C2, and C4. IC1 is four-operated, 5, 6, 7 inside the internal circuit and peripheral components constitute voltage amplifiers, change the resistance of R8 to adjust the magnification of this level. The amplified audio signal is coupled to 1, 2, 3 inside and outside the inside and outside of the internal and external circuits, eliminating human sensing and external interference signals. And improve the load capacity. Its signal is output from the 1 foot, and is shaped by C8 to 12, 13, and 14 pin, and the pulse sound wave converted into square waves from 14 pin. Adjusting W1 can change a lot. 14 foot output square wave signals are directly coupled to IC2 3 feet and 12 feet. After two op amps, it is output from 1 feet and 14 pin. 1 The square wave voltage of the foot output is coupled to the 12,13 feet of IC3. IC3 is four and non-door circuits, when 12, 13 feet are high, 2 foot output low. D7 illuminates. Adjust the capacity of C12, change the Luminescent delay time of D7. The square wave pulse of the 14 foot output of IC2 is coupled to the IC3, which 1, 2, 3, 4, 5, 6 inside and outside the inside and outside the inside and outside the internal and external circuit constitute an oscillator. 1 The foot is high and the oscillator is oscillator, sounds, and its oscillation frequency is about 2000 Hz. V2 and IC2 5 ~ ⑩ foot circuit originates and other functions. The 8, ⑨, ⑩ foot circuit constitutes a voltage detector to lose measurement accuracy when the battery voltage is too low. D1 provides a reference voltage of 4.5V, R17, W2, and R18, which provides a scaffold. Adjusting W2 can set the control voltage value, when the foot voltage is lower than the foot, the 8 pin outputs high level, D2 illuminates, indicating that the voltage is too low to replace the battery. The auxiliary measuring device consumes a small consumption and replaces a battery for more than one year. Component selection: HTD1 selected 27mm piezoelectric ceramic sheet. IC1, IC2 is selected to use LM324. IC3 uses CD4011 four and non-door, D1 selected 4.5V regulator tube, HTD2 selected 15 mm piezoelectric ceramic soundler, K selected miniature dial switches. D2 uses mini red light-emitting diodes, D7 is highly bright by micro blue, and the power supply uses four batteries, and the remaining elements are shown as shown. Installation Debug: Welding all components on the printed circuit board, loaded into the corresponding plastic box, HTD1 is fixed within the corresponding size stainless steel or plastic shell, connected with the measuring line and 3.5mm plug, adjust W1 The sensitivity is high but does not generate self-excitation oscillation; take the battery to power the battery. Turn the voltage to 4.8 V. Adjusting W2 makes D1 just shining. The V1 and R1 in the schematic are encapsulated in the sensor HTD1. The V1, R1 is not drawn on the printed board. How to use: When used, secure the blood pressure gauge arm to the arm. Place the probe HTD1 on the carrier pulse under the arm. When the air pressure is estimated, when the shrink pressure (commonly known as high pressure) 2.5 ~ 4kpa (20 ~ 30 mmHg), stop pressurization, open the discharge valve to slowly vent, when the air pressure drops to the shrink pressure, the measuring device begins to vote, and illuminates the indication. The blood pressure pressure displayed on the blood pressure gauge is a systolic pressure, and its acoustic light is synchronized with the pulse of the pulse, and the blood pressure value displayed on the blood pressure gauge is a diastolic pressure when the sound and light stops.
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