Heart Beat Sensor
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digital output of heat beat when a finger is
placed on it. When the heart beat detector
is working, the beat LED flashes in unison
with each heart beat. This digital output
can be connected to microcontroller
directly to measure the Beats Per Minute
(BPM) rate. It works on the principle of
light modulation by blood flow through
finger at each pulse.
Using the Sensor
· Connect regulated DC power supply of 5 Volts. Black wire is Ground, Next middle wire is
Brown which is output and Red wire is positive supply. These wires are also marked on PCB.
· To test sensor you only need power the sensor by connect two wires +5V and GND. You can
leave the output wire as it is. When Beat LED is off the output is at 0V.
· Put finger on the marked position, and you can view the beat LED blinking on each heart
beat.
· The output is active high for each beat and can be given directly to microcontroller for
interfacing applications.
Working
The sensor consists of a super bright red LED
and light detector. The LED needs to be super
bright as the maximum light must pass spread in
finger and detected by detector. Now, when the
heart pumps a pulse of blood through the blood
vessels, the finger becomes slightly more opaque
and so less light reached the detector. With each
heart pulse the detector signal varies. This
variation is converted to electrical pulse. This
signal is amplified and triggered through an
amplifier which outputs +5V logic level signal.
The output signal is also indicated by a LED
which blinks on each heart beat.