(previously posted in sci.engr.biomed)
- - - Seems that it could be done with a handful of off-the-shelf parts. From browsing the group, I've seen where these are often class projects.
Purpose - Determine specific muscle maximum output. Input- Standard skin electrodes. Output - LEDs preferred over sound. Requirement - no programmable chips. Application - I severed the median and ulnar nerves (and a bunch of other stuff) just above the elbow. After a couple surgeries, I've gained some motion in my thumb, and I'm trying to exerecise it to the max muscle activity level. I've used a commercial unit in the Occupational Therapy clinic, but it has a fancy LCD display with mmv readings, timers, etc. that I don't need. I visualize an output of a simple string of LEDs. If I remember correctly, the commercial unit displayed readings of 10 to 60 mmv, depending on pad placement and fatigue level. With luck, this will increase, but I don't know what normal limits are, and don't expect to get anywhere near normal levels. Changing ranges would be a nifty.
Seems it could be done with a power supply, amplifier, and LED driver chip, or maybe easier. Any suggestions?
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Ken, Thanks for the links; I'll check them out. I googled for 2 days, obviously with the wrong key words, and all I could find were block diagrams and theory. As far as skills, that's changed a tad, which leads to my request. I've breadboarded a lot, and made enough basic one-sided circuit boards to be comfortable with the process. Now, I call whatever I do 'therapy', and often recruit family to hold things for a second. :) Yes, desire is 'cheaply' - crude, if need be. A simple gazinta / comesouta. On the lines of a science fair project would be adequate. Thanks, again.
----------------------------------------------- Path: beE1!out03b.usenetserver.com!news.usenetserver.com!in04.usenetserver.com!news.usenetserver.com!nx01.iad01.newshostin g.com!newshosting.com!216.196.98.140.MISMATCH!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca. giganews.com!nntp.comcast.com!news.comcast.com.POSTED!not-for-mail NNTP-Posting-Date: Thu, 01 Feb 2007 20:33:09 -0600 Newsgroups: sci.engr.biomed Subject: Re: Req: Schematic for BASIC electromyogram (EMG) - biofeedback type device From: Ken Moffett References: Message-ID: User-Agent: Xnews/5.04.25 Date: Thu, 01 Feb 2007 20:33:09 -0600 Lines: 79 NNTP-Posting-Host: 75.72.187.89 X-Trace: sv3-swZKurxPXYUqHG9e6bu+vSXGtG1Ip1EQyMyzHu94Pus8G8XizYZk1UbZP7M1+KS3AeezBN6Y+CXoHSO!V5Z/
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Joe,
The input circuitry for EMG is very similar to that used for EEG and ECG. Basicly a high CMMR, differental amplifier with a lot of gain. The difference is in the filtering, and what you do with the output. Though in EEG and ECG they are trying to filter out the muscle (noise) signal, that you want to use.
I used to work in Biomedical Engineeing at the U of Minnesota Hospitals, but would have to dig to come up with a design from a "handfull of off-the-shelf parts"...for what I assume you want to do cheaply(?). What are your skills electronics?
Try posting your request over on the newsgroup:
sci.electronics.design
and
Google: EMG circuit schematic
I got lots of good hits, including:
GO GOPHERS!
This should do what you need for the front-end. Instead of sending the signal to a computer you could try driving an LED bar display:
You may need to put some signal conditioning circuitry between the input and the display, but I'll leave it there for others to help.
As my flight instructor used to say: "Do good work...and have fun"
Ken Moffett Scientific Instrumentation Macalester College