ECG Circuit

Status
Not open for further replies.

Thread Starter

rmmowdhgalya

Joined May 16, 2007
9
hello.. i have designed an ECG signal conditioning circuit which I have attached... I would like your suggestions on the circuit... it is a three lead ECG circuit.. The ECG signal is generated by a cardiac simulator.. the circuit is only for signal conditioning... The output of my circuit has only noise... Please do help...Kindly let me know as to where i have gone wrong.... i have to submit this in another week.. If there is a 3 lead ECG circuit already available please do send me the link... i will be very grateful..
 

Attachments

Thread Starter

rmmowdhgalya

Joined May 16, 2007
9
hello.. i have designed an ECG signal conditioning circuit which I have attached... I would like your suggestions on the circuit... it is a three lead ECG circuit.. The ECG signal is generated by a cardiac simulator.. the circuit is only for signal conditioning... The output of my circuit has only noise... Please do help...Kindly let me know as to where i have gone wrong.... i have to submit this in another week.. If there is a 3 lead ECG circuit already available please do send me the link... i will be very grateful..
 

Attachments

Thread Starter

rmmowdhgalya

Joined May 16, 2007
9
Hi iv put up a schematic of my ECG circuit.. would like ur suggestions on it... If there is a ECg circuit already available please do send me the link...
thanks in advance...
 

Distort10n

Joined Dec 25, 2006
429
Here are a few questions:

1) Why are you buffering a voltage off of the gain setting resistor from the INA114 with the OPA2131? Right leg driver? But I think that is usually from the output of the INA back to the patient.

2) You are leaving one channel of the OPA2277 floating. If you are not going to use this channel, you should place it in a voltage follower configuration using a zero ohm feedback resistor, and an open gain setting resistor. That way if you ever want to use the second channel, you already have pads for the resistors.

3) What are your general concerns?
 

Thread Starter

rmmowdhgalya

Joined May 16, 2007
9
1. I got details of the right leg driver part of the circuit from a book on Biomedical Instrumentation by Joseph J Carr and I also saw it in the datasheet of Ina 114.
2. My concern is that im not getting the required ECG output and the frequency of my output signal is around 50Hz which I feel is the power line interference. And the output is mainly noise.

Thank you
 

Distort10n

Joined Dec 25, 2006
429
Yowza, so it is. I am guessing it serves to keep the shield at a reference potential within the common-mode range of the INA114. This is something I will have to dig deeper into myself.

THe INA114 has good CMRR at 50/60 Hz, so you should be good there. Olimex (?) creates boards for the Open EEG project. That might be a good place to go and see if there is any extra filtering on the inputs.
 

amiyasar

Joined Nov 27, 2008
1
My experience with ECG is quite painful. What I get is only hum. I used TL084 and TL082 ICs, an optional filter with jumper options and computer scope software from C Zeitnitz. Did not use Optocoupler. In the schematic, asterix represent test points. The 2(two) 22k resistors were meant to act as load resistance for the filter.
Can I use center zero voltmeter to bypass the computer hum? Electronics geeks Please advice. Thanks
 

KMoffett

Joined Dec 19, 2007
2,826
I have an ECG simulator circuit that a friend built many years ago. I have attached the circuit and examples of the output waveforms. A bit dated technology, but it worked. Now he would probably use a PIC with a look-up table and a filtered PWM output.

Sorry about the size, but I needed to retain detail.

Credit goes to John Kruse, Minneapolis VA

Oops! Thought I was posting to: http://forum.allaboutcircuits.com/showthread.php?t=28854

Ken
 

Attachments

Last edited:

Audioguru

Joined Dec 20, 2007
11,249
This is similar to your circuit. It is easy to see because it uses opamp symbols intead of the boxes used in your schematic. It has matched resistors for good common-mode noise cancellation.
 

Attachments

Status
Not open for further replies.
Top