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Heart beat sensor is designed to give digital output of heat beat when a thumb finger is placed between the LDR & LED 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.  

The sensor consists of a super bright red LED and a LDR light detector. The LED used is of super bright as the maximum light should spread in finger and detected by LDR. Now, when the heart pumps a pulse of blood through the blood vessels, the finger becomes slightly more opaque and so less light reach the LDR. 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.  

While placing the Thumb finger , the Nail side should face LDR & Flesh side should face LED.


· Heat beat indication by LED
· O
utput digital signal for directly connecting to microcontroller
· Compact Size
· Working Voltage +5V DC

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