Electrocardiograph & Heart Rate Monitor

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Picture of Electrocardiograph & Heart Rate Monitor
This instructable shows you how to make an electrocardiograph and a heart rate monitor. It is intended to be a fun science project only. Of course, it should not serve as a medical purpose.

PLEASE NOTE : To avoid any risk of electric shock, only use battery alimentation. Electrodes are theorically isolated from the circuit by the instrumentation amplifier, but play safe. I'm not responsible for any accident that may happen. 

This is a simple design that fits on a single breadboard. You are free to experiment and to custom it for your needs.

Since it's my first Instructable and also since English is my second langage, don't hesitate to contact me if you find an error or if you want some clarifications about a section or another. I will be happy to edit my project for the better!
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Step 1: List of Materials

Picture of List of Materials
- (1) Instrumentation amplifier INA128
- (1) Operational amplifier 741
- (1) Arduino Uno
- (1) 16x2 characters Liquid crystal display
- (1) Voltage regulator 7805
- (1) 8 ohms mini speaker
- (1) Brigth LED (I use a 10 mm one)
- (1) Diode 1N3064
- (2) 9V Batteries with connectors
-  Breadboard
-  Jump wires
Resistors :
- (2) 100 ohms, 1/4W
- (1) 470 ohms, 1/4W
- (1) 1 kiloohms, 1/4W
- (2) 10 kiloohms, 1/4W
- (2) 100 kiloohms, 1/4W
- (1) 1 Megaohms, 1/4W
Capacitors :
- (1) 10 nF
- (1) 47 nF

For the electrodes :
- About one meter of speaker wire
- Antistatic wrist strap
- Medical tape
- Aluminum paper
- (2) metallic paper clips
- Shower gel (a substitute for electrocardiogram gel)

Optional but recommended:
-Oscilloscope, for the electrocardiography part of the device
heriss6911 days ago

Is it possible to convert this into a pacemaker? Like with a few added steps?

birdyberth (author)  heriss699 days ago

If I were you I wouldn't try that.

gada88824 days ago

is it possible for me to replace the Diode 1N3064 with 1N4001

birdyberth (author)  gada88821 days ago

Yes, it's possible. Pretty much any ordinary diode will do the job.

atolat1 month ago

Could you please explain the pulse counting logic?

birdyberth (author)  atolat29 days ago

It's an edge trigger, so it activates the counter only if the pin has just changed its state and if the pin is high.

tal satti1 month ago

nice project and thanks for sharing , i just wanted to ask u, is it possible to place the electrodes around the leg ? because i want to integrate the heart rate sensor to my project which is also placed at the ankle

birdyberth (author)  tal satti1 month ago

Thank you! In this case, I'm afraid it would probably pick up more the leg muscles movements than the heart signal. Good luck!

fzunana1 month ago

Hi, excellent proyect! Do you think its possible to make it store data? or send an exam to a device like a cellphone, ipad, via bluetooth?? like this one

once again, great work!

birdyberth (author)  fzunana1 month ago

Thank you! Yes, it could store the heart rate on a SD card if you add an SD card shield on the arduino or send it through bluetooth if you add a bluetooth shield... If you want to send the complete signal, you will have to modify the circuit... I don't know how, but that should be feasible.

jessyratfink2 months ago

This is brilliant. Great work!

birdyberth (author)  jessyratfink2 months ago

Thank you!

Hi birdyberth is there any chance you can make this work without the LCD or the speaker? I have built it and attached the probes but I dont seem to get the LED flashing or any output in my oscilloscope

sinzu1 month ago

Nice project !

Do you think it could be possible to use a similar method to build an electromyography (EMG) system to record the activity of a muscle instead of the hearth ?

birdyberth (author)  sinzu1 month ago

Thank you! That is definitely a good idea and it was already in my list of future projects! I will work on it in a few months. You can also try it by yourself!

kurtee2 months ago

Great project!

Think about creating a front end program using processing instead of a separate oscilloscope !

The electrocardiograph could be displayed on your computer.

birdyberth (author)  kurtee1 month ago

Thank you! I'm more interested by electronics than programming, but if someone use my work to create that I will be happy!

javiforex2 months ago

Cordial saludo

amigo, desde colombia Bogota (dc), gran proyecto,



birdyberth (author)  javiforex1 month ago


Rogie-Bear2 months ago

Hi birdyberth,

A quick and dirty solution for electrodes is to attach each lead to a few square centimetres of foil. Place the two pieces of foil into separate dishes containing salt water. When ready, place one hand in each dish. This should give you a strong clean tracing that corresponds to Lead1 on a professional ECG.

Top marks for top 'ibble.

birdyberth (author)  Rogie-Bear1 month ago

Thank you for the advice!

thank,s a lot !

J-Salcedo2 months ago
What The 7805 ic do? I cant see the pinout correctly. Could you explain me?

Its a voltage regulator, it drops from 9V from the battery to 5V to supply the circuit.

birdyberth (author)  J-Salcedo2 months ago

Yeah sorry the part in Fritzing is somewhat smaller than the others... It takes the 9V of the battery and makes -5V to supply the amplifiers. The pinout is :

Input : +9V (battery)

Ground : 0V of the battery and -5V for the rest of the circuit

Output : Ground of the circuit

In short, you can see the 7805 as a 5V source that you put backwards in the circuit to have -5V.

Ugifer2 months ago

This is great and I'm totally making this!

Would love a little more detail on making the electrodes: is the wrist-strap just for the ankle? Are you joining the foil to the speaker wire with the paper-clips or is there something more? Where abouts do the electrodes go on the chest? How high? How far from centre?

One other thought? Could we use a sports heart-rate monitor electrode strap? Like this:

Keep up the great instructables!


Ugifer Ugifer2 months ago

Or TENS pads. They might make good electrodes, and they're pretty cheap!

birdyberth (author)  Ugifer2 months ago

Thank you! I strongly suggest that you experiment and share your results! It would probably be simple to hack a sport strap, and those TENS pads really look like electrocardiograph electrodes. I have a good feeling for both of these!

Ugifer Ugifer2 months ago

I'm sorry - for some reason I missed the last two steps, which show exactly what I had hoped you would cover. Opps. Carry on!


jgueydan2 months ago
What model oscilloscope is that? Great project!
bondy100 jgueydan2 months ago

It looks like this oscilloscope (dso nano nano).

birdyberth (author)  bondy1002 months ago

Yes, it's a dso nano v2. A great oscilloscope for students and beginners.

ninjanody2 months ago

Great project. Hope to see updates (arduino bord shield and better electrodes...)

birdyberth (author)  ninjanody2 months ago

Thank you! I'm on some other projects for now, but I'm open to suggestions... It would effectively be great to make a shield with a LCD that displays the signal (no need for scope then!) For the electrodes, it was the cheapest and simplest way I found and it works maybe quarter of the time... It's not as easy as it seems, and my budget is limited!


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