I need a circuit design for a 2 Lead Dry contact electrode ECG system. I am selecting INAMP & OPAMP for the design. Please suggest me a very good working circuit & IC'S. Please I am not preferring ADSXXXX series.
My requirements are as fallows,
1. It is a handheld equipment with battery powered, so the power consumption should be less.
2. The production quantity is 2000 piece/month, so the cost of the chip & circuit should be very less.
3. The circuit should have very good reliability & repeatability.
3. The electrodes contact with thump [dry contact], so the sensitivity should be linear for all type of skins.
Please provide me necessary support to start my project....
Thanks & regards
We have a design that requires contact with both thumbs and oppossing fingers. Basically, this is a 3-wire connection with two being for differential input and one for common-mode drive. It is a dry contact system. Would this be of interest to you?
PA - Linear Applications Engineering
Thanks for the reply. Yes i am looking for that circuit. Can you share with me the recommended part number, ideas, application notes & the circuit diagram if possible.
I am eagerly waiting for your reply...
Can you provide me your email address? I have a TI Tech Day ECG PowerPoint presentation that I would like to send directly to you. It contains the circuit information. It is a very large file and I may need to do some work on it to get it down to a size that doesn't get blocked by our system.
If you do not wish to list your email address on the forum, send a message to me at mine:
Please send me the information to my email address (firstname.lastname@example.org). If any EVB kit available please share the detail also...
Sorry my email id ( email@example.com ) Can you resend the email please....
The ECG presentation will be sent to the email address you have provided. The ECG board was developed for demonstration purposes and was never produced as a EVM. I do think there is enough information in the session that you should be able to construct your own prototype.
Note that in the presentation the INA326 instrumentation amplifier is used in the ECG circuit. It is fine for the application, but a newer higher performance instrumentation amplifier is now available, the INA826. It uses much less power and has lower noise than the INA326. You may wish to consider the newer device for your application. The pin-outs are different and some other minor circuit changes may be required to use the INA826.
Thank you very much for the PPT. The circuits & explanations are teach me a lot about DAS/ECG. But the presentation doesn't show me a real output of the ECG waveform from your circuit. I hope the output will be very good and noise free. There is no EVM to purchase. So please do not close the conversation, i will come back with my result.
The PowerPoint is intended to provide basic ECG concepts and some circuit ideas behind constructing a ECG demo circuit. The demo circuit is capable of producing an ECG output that can be displayed on a common DSO. When the session was presented in the past an audience volunteer would be used to observe their ECG waveform. We always had them clean their hands first with a pre-moistened wipe, allow their fingers to dry and then contact the PC board thumb/finger contacts as shown in the slides. The volunteer was seated and needed to be still while grasping the board during the measurement. Usually, it is not difficult to obtain a good, clean ECG waveform from voulnteer. I don't recall the exact DSO vertical volts per division setting, but I do think it was on the order of 50, or 100 mV/div.
Some engineering will be required to get your ECG prototype going, but the circuits are straightforward and shouldn't be difficult to get working.
yes, the circuit in the powerpoint is to measure the heart beat not exactly for ECG waveform. Even thought if it is, i hope we can get some decent output waveform. Now i am having INA326 with me. Can i use OP07D opamp for testing purpose? For quick check i am going to design a single side home made PCB with INA326 & OP07D with some through hole component. Can i proceed with this OPAMP or not????
I do not think the OP07D is a good choice to replace the RRIO CMOS operational amplifiers used in the DAS/ECG demo application. The OP07D is intended for a minimum supply of +/-3 V (6 V) and +/-15 V typical. The DAS/ECG amplifiers are powered are all powered by a single +5 V supply that appears after the input regulator. Also, the OP07D common-mode input and output swing ranges are much restricted relative to the power supply rails when compared to what is achievable with the recommended RRIO CMOS amplifiers. That may result in limited performance even if you were to increase the OP07D supply voltage to the minimum.
I am not certain what capabilites are provided by TI in your country, but in many countries free product samples are often available through the TI web site.
I am also working on a dry contact ECG system and would appreciate your help. Currently we have a biopotential amplifier circuit using discrete components and INA333 and OPA2333 that works well with leads placed on the chest, but not well with thumb leads. Although, a readable signal is possible.
To get a better signal and/or to reduce the component count, I am evaluating ADS1298and I have the ADS1298ECG-FE evaluation board with me. I get good results with an ECG simulator, but now when I test with my thumbs the signal is worse than our discrete circuit and also has a very strong baseline drift. Do you have any guidelines for finger leads with ADS1298? I am directly feeding the finger signals captured from an electrode to ADS1298, should I be doing some pre-processing?
I would also be interested in the dry contact circuit you have mentioned above, could you send me a copy of the presentation too? My email address is - govind at reka dot net.
Thanks in advance!
I will forward the DAS/ECG PowerPoint to the email address you provided. Also, I have contacted our data converter applications team to assist you with your questions regarding the ADS1298.
I am experimenting right foot feedback circuit from Webster's Medical Instrumentation book.
I would be very appreciate if you can send me the above mentioned circuit. My email is [lionel.thiha @live.com]. thanks.
I will send the DAS/ECG PowerPoint file to the email address you have provided.
Best regards, Thomas
I'm working with an eye movement detector and I guess it will be helpfull to take a look to the powerpoint you've mentioned.
I already built one with discrete Op. Amp. but now I'm looking for better performance, less consume and reduced size so I'm trying to find the better Inst. Amp. which fits with my requirements.
My email address is firstname.lastname@example.org.
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