Introduction to develop Heartbeat Display science project
Heartbeat display is a simple DIY science project. Heart is an important part of our body and the heartbeat being the parameter to measure its soundness. Heartbeat monitoring is vital for many persons having heart ailment. The cost of many heartbeat display are costly, here we are trying to develop a low cost one and that to with minimal components. The best part is the no use of any controllers. This DIY science project of developing a heartbeat display system will be a good science project for the school goers.
Block Diagram of Heartbeat Display
The block diagram for the DIY science project will give the pictorial representation of how the different blocks are connected to make a heartbeat display system. The output from the heartbeat sensor is given to the counter. The three counters IC are provided for the unit place, ten places and hundred places. These values are given as an input the seven segment display IC.
Circuit Diagram of Heartbeat Display
Working of Heartbeat Display
Heartbeat sensor is used here to detect the heartbeat of the person. It works on the principle of photophlethysmography. It basically consists of a light source and light detector. LED act as the required light source. The device here is designed to be wear as a cap over one of the finger. The user has to wear it over the finger. The LED will be emitting light continuously and this will be detected by a photodiode which act as a light detector. Whenever the heart pumps the blood the light from the LED is absorbed by the increased blood cell. This variation in intensity will cause an increase in the resistance of the photodiode. Using an OP-Amp this variation is converted to a voltage signal. Basically an analog to digital conversion occurs there and these digital values are fed to the counter. This section is the main part of this heartbeat display system.
To start the measurement a switch is provided. This switch is connected to 555 timer. 555 timer is basically an astable multivibrator used for timing applications. The switch is connected to the trigger pin i.e. pin 2 of the timer. In this DIY science project the 555 timer is used to introduce a delay of 1 minute. Generally the heartbeat is measured for a period of 1 minute. For that reason a delay of 1 min is introduced. When the switch is activated the 555 timer becomes active simultaneously the counter IC is also made active. The counter IC used here is 4026. A 'NOT' counter 74LS04 is provided as the output from the 555 timer is high and clk' input of counter IC is logic low.
The counter IC will take the reading for the specified 1 min. The first counter IC will read up to 0-9 and it is for the reading of unit place. When it crosses the value 9 the second counter become active it will take the reading of the ten’s place. If it exceeds the value of 99 then the final and third counter IC will become active. This will give the hundred’s place.
After 1 min the 555 timer gets off. The counter IC has inbuilt 4 bit to BCD convertor which will do the necessary conversion .The value will be forwarded to the seven segment display unit to get it displayed. There will be 3 display units to read the observed value.
A simple low cost and cost effective heartbeat display unit is developed with minimal components. It will be a great DIY science project.You can develop a heart beat sensor instead of a module by checking this link: https://www.mepits.com/project/47/Project-Kits/Simple-DIY-Project---Heartbeat-Sensor.