Hey all, I'm looking to make this into a quick 1-day project. I found this
website:

website: http://www.eng.utah.edu/~jnguyen/ecg/instructions.html

and this schematic:

schematic: http://www.eng.utah.edu/~jnguyen/ecg/bigsch.gif

for building your own electrocardiograph. It's basically a few opamps hooke=
d
up into your sound card.

1(Q). I don't have *those* specific opamps, as shown on the schematic (LM32=
4
http://www.national.com/mpf/LM/LM324.html#Overview) or (LF353
http://www.national.com/mpf/LF/LF353.html#Overview), but I can go to the
local electronics store to buy some. I looked on Linear Technology's and
Maxim's site for some opamp samples but they all have so many different
parameters with wide ranges that I'm not familiar with. Generally what
parameters and what value ranges should I be looking for in an opamp for
this project when I go to the store? For example: gain, bandwidth, slew
rate, and so on, and what ranges for each?

2. I don't want to be hooking up any part of my body to my computer (I've
had bad experiences with ground loops? in the past. Remember the "magic
smoke" from that HH44780 display?). So before converting the signal to
digital with a microcontroller and optoisolating it, I just want to hook up
a simple LED to flash when the trigger level has passed (when the heart
beats). For this, I'm guessing I'd need to hook up the output of the circui=
t
to a comparator and set the reference voltage via a comparator, then drive
an LED with the comparator's output. Hopefully, the LED will blink slow
enough for the human eye to see.

2a(Q). Is the comparator method the right way to go about it?

2b(Q). If it is, when I go buy a comparator and the rest of the parts
(hopefully today), are there any special parameters I need to look for in a
comparator?

3(Q). I just realized - I have a laptop which runs on batteries, so it
should be safe to plug into the laptop's microphone input jack and record a
waveform with audacity?
--=20
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