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By
Amith G
Anoop Kumar
Babeesh C
Remya Raj
www.edutalks.org
The project aims to design a heartbeat counter. It amplifies the weak cardiac signals counter. It amplifies the weak cardiac signals and counts it.
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Heart beat rate = 72 beats per minute
Basic analysis for any kind of diagnosis
Monitoring of heart and breath sound done with the aid of a stethoscope
Many problems like missing a cardiac beat, less efficiency in detecting the change in breath efficiency in detecting the change in breath sound.
Development of electronic stethoscope extended to heartbeat counter.
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Sensor
AudioLeveling
Astable
MonostableMultivibrator
Counter
Amplifier
AstableMultivibator
Counter
Latching
7 Segment Display
Decoder
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A sensor is used to convert the weak cardiac signals in the sound form to electric signals
The signal is amplified through different stages about 200 times
Different levels of the signal is taken using an audio leveler.audio leveler.
Monoshot is used to shape the signal & can be used for counting. This is fed to a counter.
Astable is used to reset the counter.
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The counter output after 1 minute is latched
The latched output is decoded and displayed using a 7 segment display.
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The circuit consist mainly of 2 sections
Amplifier section
Counter section
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� Electret microphone - sensor used.
Week cardiac signal ranging from 0.4Hz - 0.6Hz to electric signal.
� U1– low noise microphone preamp.
Gain -3.9
Effective input resistor decreases
C2 pass the low frequency heart signals.
TL072 used
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� U2 – Low- noise Sallen & Key filterButterworth typeCut off frequency – 103 HzR7, R8 – provide gain of 1.6 eachUsing TL072 dual Opamp
� U3 – Power amplifiergain- 20gain- 20Drive any type of headphones
So the amplifier section has a total gain of 200 from the whole amplifier section
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The output from the amplifier part is fed to the counter section.
� U4 – audio levelerOutput from the amplifier part is fed
Signal levels are seperatedSignal levels are seperated
� U5 – monostable multivibrator using 555 ICOff period of 1millisecond
Trigger through C7
T= 1.1 RC
Output as clock of counter IC
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� U6 – Astable multivibrator using 555 IC
Output to the reset pin of the counter IC 7490
Set for a time period of 1 minute
Ton = 450 ms and Toff = 550 ms
U7,U8 – BCD Decade Counter� U7,U8 – BCD Decade Counter
U7 for lower bits
U8 for higher bits
U8 triggered when U7 reaches 1001
Counts from 0 to 99
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� U10 – Latch IC
3 state octal buffer
Holds the final value after 1 minute to display it
Output Enable pin is active when input is low
OE fed with inverted astable output done using an inverting amplifier of unity gain.
Output of pin nos: 18,16,14,12 give the lower bits & Output of pin nos: 18,16,14,12 give the lower bits & that from 3,5,7,9 give the upper bits
� U11,U12 - decode
Converts BCD input data into control signals.
The output form the control signals for the 7 segment display
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Reduces noise
Amplification is about 200 times
Display the heartbeat rate in 1 minute
More scientificMore scientific
Reduces error
Increased accuracy in identifying the breathing rhythm.
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BP level measured
60 beats per minute <heartbeats<120 beats per minute – Normal heartbeat Rate
Heartbeats <60beats per minute – Hypotension
Heartbeats >120 beats per minute – Hyper TensionHeartbeats >120 beats per minute – Hyper Tension
Use as a stethoscope
Valve damage detected from the sound variations
All basic diagnosis involve heartbeat count
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The heartbeat counter is designed and set up. The signal from heart is sensed, amplified and counted in an heartbeat counter. The heartbeat counter can also be used as an electronic stethoscope. electronic stethoscope.
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