DIY ECG and Pulse Oximeter with LM324 OpAmp (1 of 2)
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- เผยแพร่เมื่อ 26 ก.ย. 2024
- ECG using a single LM324 which doubles as a pulse oximeter. This device can be used with chest pads to yield an ECG or with an LED and phototransistor for pulse oximetery.
IMPROVED ECG PROJECT: th-cam.com/users/wa...
Project page:
www.swharden.c...
Description:
Single LM324 quad operational amplifier using all 4 amps: (1) virtual ground, (2) preamplifier, (3) lowpass filter, (4) final amplifier and second lowpass filter. It doubles as a pulse oximeter (near rail-to-rail swing at 12V and 5V) with a phototransistor, and an ECG (about 0.5 V output).
As a high school student interested in electronics / engineering, you inspire me, sir. Excellent!
Just a little comment at 4:20 - You say you have "a relatively small amount of 60Hz noise over there". I should correct you: You have NONE! That is exactly what you had to achieve. That is the "dicrotic notch" which you think it is a noise, which is absolutely vital and physiological. Thumbs up for your great work, mate!
@József Farkas I think he means the noise that causes the whole dot to be a little bit "smeared" out.
thanks for the video lil bro. Ive been looking for something like this for a while. keep up the good work
I really admire your work. Thanks for sharing your experiments!
Super impressive project. Amazing.
Agreed. It's more of a light-based pulse detection circuit. I detail it further in my web page which documents it fully. As you say, graphing the ratio of red/infrared would provide a quantitative measurement of blood oxygenation.
Amazing work! Do you have any idea how we can calculate SpO2 momentarily?
give the link to your webpage
@@convolution_talk_show It's in the description
This instructional video is so easy to follow
Beautifully done . Great job !
Is there a specific photo transistor to use? can you provide the site to where you found yours.... thanks
I cant seem to get my phototransistor to pick up any noticeable voltage change in my finger, my output is either high (12vdc) or low (gnd) but no heart beat fluxuation , tried swapping decoupling caps there is just no small signal to amplify, im not giving up though, I did just use a red led instead of an actual infrared diode, ill try using the infrared diode this time...
Nice job but technically, this is not an "oximeter" because you are not measuring the amount of oxygen in blood but the variations in the amount of blood in blood vessels due to heart beating. In the case of EKG (ECG), you have to be careful with leakage currents that circulate from your heart to the oscilloscope, in given circumstances and in the worst case, they can lead to heart fibrillation.
Yes..and should only use a battery as power supply
@@fritzschnitzmueller3768 Don't worry so much.
Nice circuit, just have to mention that it's not actually a oximeter since there isn't an IR led with which you can do comparison to actually determine oxidation.
Thank you for this! Do you know if it’s possible to get the precordial leads?
Great project! I think I saw a DIY EEG a while ago that functioned in a similar way.
Also, how do you get the oximetry data out of this?
I have the same question and i still couldn't find how to.
Hi, I am trying to duplicate your work but with 5v source voltage and later feeding it to one of the analog inputs of an arduino, but somehow I failed to mimic your results. I am using a IR led instead of a red led, also I don't see the polarity for the 0.22 micro farads capacitors in your diagram.
Hi Scott Harden , So you have to give the output of Virtual Gnd Ckt to +ve V ( not Vcc Obviously ) of Amp 1 2 and 3 ?
And by pre amplifier Input you mean the Output of Photo transistor, right ?
Please Help.
I'm new to Electronics. Thanks.
Can you explain how you knew to use a 0.22uF capacitor as a coupler? And also how to determine what the supply voltage should be for the circuit?
this circuit is so simple i liked it , but still i need to measure the o2 rate in blood , i need a simple circuit for my graduation project , do you any website gives simple circuit , i cant buy ready one (they dont accept it ) i need to made one my self . and again this video is great you are simply great :)
hey :) if incase u hav found the circuit diagram for the oximeter would u please share it with me.. I need it for the college project too :) thanks
@@MrEzlen I have the same graduation project. Could you find out anything? It would be just amazing if you could share :D
Could you find anything related sir? I have the same project and it could be really helpful if you have found something :)
@@isoaso344 could you give me your mail address I had done that about 4 years ago.. i will have to check if i still have it
@@MrEzlen Thanks for your reply. My e-mail address is: hia1998@hotmail.com I will delete this comment in 1-2 hour since there may be someone who wants to troll me through my e-mail :D
sir question, is the resistance of the resistor at the detector circuit with the phototransistor just equal to the emitter circuit which is 1800 ohms?
For the sticky pads on your skin, are they connected to your circuit via a twisted pair of wires? That alone could help reduce the 60Hz noise. I am amazed at how sensitive the pulse-ox is to your pulse! Nice work! You should feed it into a data logger for analysis 500 samples/sec should be fast enough.
This is a pulse detector not an oximeter. It does not measure the oxygen level in the capillary bed as do pulse oximeters or oximeters.
Yes he is obviously carried away by his own book learning shit.
Agreed but do you have any idea how to build a SpO2 circuit? It would be great if you can share :)
This video is a few years old, but because of COVID-19 people are looking for affordable ways to expand monitoring of COVID patients so that better treatment decisions can be made earlier.
I just want to caution everyone to be extremely careful with DIY ECG. The primary issue is electrodes are designed to eliminate (as much as possible) the resistance of the skin, that means whatever current is flowing through the leads is going to flow directly through your heart.
The maximum current allowed in commercial ECG devices is
Hi Noah, thank you for clearly stating this important message! This video is several years old, and moderately improved safety may be achieved by using a commercially-available ECG sensor board th-cam.com/video/sP_-f5nsOEo/w-d-xo.html although a good understanding of electronics and attention to safety is required whenever one uses or experiments with medical devices.
@@swharden
We're actually using the AD8233 chip to develop a portable, OSHW ICU monitor, they're nifty little chips :)
Patient isolation is the big thing, you want to make sure that no matter what happens the patient is never in the path to earth. Which, for the most part running this IC off battery power does, but connecting directly to the mic jack of a computer presents an opportunity (although very slim) for the patient to become a path to ground, this gets even riskier if more devices are attached to the patient
Here's a primer on that www.asnm.org/blogpost/1635804/289003/Understanding-Patient-Grounding
To step up safety a bit more you might want to consider running an ADC inside the device itself (off the battery power) then have an opto-isolated connection to the computer you're displaying it on.
I think the easiest way to do it might be a two microcontroller setup, have one doing the ADC running off battery power communicating to a second controller via an optocoupled I2C bus, then have the second microcontroller (powered by USB) handling the USB connection to a computer.
Alternatively, you could use analog opto-couplers, I'd imagine you'd need 2 of them (1 for each lead to get + and - readings), but analog signal isolation is quite a bit harder than digital (and the ICs are more expensive too)
@@noahw4623 These are more excellent points, and patient isolation is a good topic to read about. I encourage you to review the AD8232 datasheet (Fig 66) or AD8233 datasheet (Fig 72). You will find that none of the 3 body leads are grounded. My understanding is that no path to ground is provided to the patient, even if the output of that chip is fed into a computer sound card.
I want to SpO2 arduino code. its urgent
Engineering project isn't it? I'm curious what you're doing now? Working, higher education?
Asking because I'm in your place today.
Why don't you write yourself and ask doubt on stack overflow than being a copycat who knows nothing??
Keep us updated
Which phototransistor you used here?
Amazing work! This is a great pulse sensor but is there any way to obtain SpO2 value from the circuit you made? Again, thanks for your effort. :)
Can u put step by step of the process on your description box next?
aina amlia saman the project page linked to in the description contains this information 👍
how the sound card is used... i mean wats de input to it....
awsome
Awesome vid's good sir
can you u give me the list of component which is used in this
www.swharden.com/wp/2013-04-14-simple-diy-ecg-pulse-oximeter-version-2/
Scott Harden bro I am in project which is related to ECG Using lab view so can u give me your gmail which is good for me
NICE
not ecg it just pulse
False. ECG shown 4:50
wrong plane of ecg
Hi, what email to contact?
Realllly appreciate your effortss