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Step 2: Signal conditioning circuit

The reflected IR signal detected by the photo diode is fed to a signal conditioning circuit that filters the unwanted signals and boost the desired pulse signal. The circuit diagram above shows the IR LED (D1) and the photo diode (D2) along with the signal conditioning circuit made of two stage operational amplifiers configured as active low pass filters. The cut-off frequencies of both the filters are set to about 2.5 Hz, and so it can measure the pulse rate up to 2.5*60 = 150 bpm. The gain of each filter is about 100, which gives the total 2-stage amplification of 10000. This is good enough to convert the weak pulsating signal into a TTL pulse. Note that at the input of each OpAmp filter stage, there is a 1 uF capacitor to block any DC component in the signal. At the output is connected a LED that will blink with heart beat. The cathode of LED gets the ground path through the collector of BC547 transistor. In order to save the battery life, the transistor is turned on for 15 seconds by PIC16F628A microcontroller while the measurement is going on. The number of pulses counted within this interval is multiplied by 4 to get actual beats per minutes (bpm).  
<p>Done it, it was my first bigger project, and maybe too hard for beginner. But code is working only on PIC16F628A, but not on a PIC16F628</p>
Nice
<p>hello brother if u had really made it then plz mail me full details at .</p><p>vipulverma266@gmail.com</p>
<p>Hi</p><p>Can you send me the code for the project. Thanks.</p>
<p>Hey i have a question have made the IR led at the sensor on/off(blinking) for few secs or just kept on ???</p>
<p>keep on, your blood pressure will &quot;imitate the blinking&quot;</p>
<p>what is the logic used to calculate heart rate ?</p>
<p>did u have the source code and the schematic??i want it please iqramkyoya@gmail.com</p>
<p>yes, but everything is in subscription</p>
<p>hello sir ! do u have any kind of project details? can u send to me</p><p>bungatulip6617@rocketmail.com</p><p>tq sir..</p>
<p>good day sir, can you please send me the pcb layout that you made im kind of new to this project. please help me.</p><p>email add: derek.gabs@gmail.com</p>
<p>hello sir, i am going to do this project for my final year project submission. can you please mail me the details and source code for this project? it will help me a lot.</p><p>my mail id mitraniloy@gmail.com.</p><p>thanks in advance.</p>
<p>Good Day Sir!</p><p>Can you give me the pcb layout of your project.??? :)</p><p>And the simulation of this project if you don't mind.</p><p>Hope to reply as soon as possible.</p><p>Thank You so MUCH.</p><p>GODBLESS. </p><p>This is my e-mail address. </p><p>skyweak0024@gmail.com</p>
<p>Good Day Sir!</p><p>Can you give me the pcb layout of your project.??? :)</p><p>And the simulation of this project if you don't mind.</p><p>Hope to reply as soon as possible.</p><p>Thank You so MUCH.</p><p>GODBLESS. </p><p>This is my e-mail address. </p><p>skyweak0024@gmail.com</p>
<p>my dear .. plz connect this project but it not work &gt;&gt; i was using pic16f628a </p><p>but it not work !!</p><p>plz send me the source code and all names of all components and explain to me how you connect the circuit on akrm33766@yahoo.com </p><p>or on facebook https://www.facebook.com/akram44444</p>
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Wtf
Dear sir,<br>My heartbeat sensor which i have made using ldr and led,detect the movement of finger but not blood flow.<br>So please help me.<br>By: shailesh<br>Email: shuklask8@gmail.com
My heart beat sensor which is made by led and ldr ,detect movement of finger but not blood flow.so please help me.<br>From:shailesh<br>Email:shuklask8@gmail.com
<p>Dear Sir,</p><p>I am student in South Africa at Tshwane University of Technology studying Electrical Engineering in the Clinical Engineering field. i am impressed by the project and would like to build it and test my capability of micro components concerning my field.</p><p>Can you kindly send me the components list at patsonnenzhelele@gmail.com</p>
<p>Hello Sir,</p><p> I'm doing my BE ECE 2nd year right now. I was impressed by your project eventhough it seemed advanced to a beginner like me. I think am almost done with the circuit except for the programming of PIC16F628A. I tried using pickit2 programmer and mikroC. But both failed me (coz i dont know the basic configuration). I tried many ways but i failed. Please help me :( :'(. if you could find in a great heart to help me step by step it ll be very useful for me. My email id:rkishorekumar1996@gmail.com. Pls do help me. Thank you so much in advance.<br><br>With regards,</p><p>Kishore.</p>
<p>awesome project :)<br>if any one get the C code .... please <br>share with us :)<br>eng.ahmed.shikhoun@gmial.com .</p>
<p>Hi, if anyone can send me the C code of the project or more details about it. Thanks.</p><p>baydoun.1992@hotmail.com</p>
working absolutely fine
<p>can you send me a list of the parts that you have used please. Thank you.</p>
<p>Sir can you kindly send me the necessary codes ,simulation files and PCB layout file. My email address is asif.chowdhury9663@gmail.com</p>
<p>If you receive this info could you forward it to me as well? nlittell@iupui.edu</p>
<p>Can I ask for the program code? Please. </p><p>Please send it here: annrosejessica@gmail.com. </p><p>Thank you in advance. </p>
<p>hello, do you have the details of this project? can you please send me? </p><p>mail id mitraniloy@gmail.com</p><p>thanks in advance</p>
<p>hey dude!!! can u send me the details about components!! urgent!! </p><p>ashurumarabia@gmail.com</p>
Sorry for replying so late .... everything along with source code is given in thr instructable but still if u find any difficuly feel free to contact
<p>hey dude!!! i'm interested on this project ...please save my life... :( its a urgent case</p><p>can u send me the details about this project, the programmings codes/ and other details??!....</p><p>here my email : mohamadhakim97@yahoo.com</p>
<p>i liked this circuit.buddy wil u plz snd me the program code and other detaiil to my mail id(sojanthomas966@gmail.com) plzzzzzzzzzzzzz</p>
<p>can you send me part list required for this</p>
<p>hey man. could you send me the programming codes and other details? my email address is varun9523@gmail.com</p>
<p>heloo cooldharap can u help me pease related to this project?? I have selected it as final year project... thanks</p>
<p>please do send me the source codes dude!! </p>
<p>i'm interested in building this one. Could you please mail me the necessary component details at souravguragai@gmail.com</p>
<p>thanks it's very Interesting</p>
<p>plz iwant this project to submit in my college.</p><p>plz send all infirmation related to this to my mail id</p><p>kamleshchoudhary4444@gmail.com</p>
<p>i want to make it with Atmega 32a can i??</p><p>give a code in C</p>
<p>please can I get the program code(PIC16F628A) and details to ajaymarag@gmail.com thanks</p>
Please can I get the program code(PIC16F887) and details to rotimyj@gmail.com..... Thanks
Please can I get the program code(PIC16F887) and details to rotimyj@gmail.com..... Thanks
Hello, can u please send d program code to me. I want to use it as my project. Thanks

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