24 February 2017
BUILD IT YOURSELF
I find medical instruments
like an ECG-EKG unit
really fascinating. To be
able to watch the
electronic firing signals of
a heart is mesmerizing
and informative. The
patterns tell you, for
example, if you have
arrhythmia (irregular
rhythm or beat), too little
or too much potassium in
your blood, ischemia (a
lack of blood flow to the
heart muscle), damaged
heart muscle (after a heart
attack), fibrillation (when
the heart just quivers and
doesn’t fully pump), your
heart rate, and much
more. For the rest of this
article, I will refer to the
unit as an ECG (
Electro-Cardio Gram).
Build Your Own
ECG-EKG
UNIT
By Ron Hoffman
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If you’ve ever had an ECG at your doctor’s office, the bill for it can run anywhere from $100 for a standard three-lead test to $1,200 for a 12-lead test. Being an engineer and inventor, I
wanted to see if I could come up with a really good low cost way
of designing and building my own unit so I could check out my
own heart signals. The effort was fraught with design trial and
error, and many lessons to be learned along the way. The result
was better than I ever imagined.
For parts costing less than $50, I built an ECG unit that plugs
into my laptop computer’s microphone input jack and displays
stunningly clear ECG waveforms. It uses a single quad RRIO (
rail-to-rail, input-output) op-amp and features a red LED that blinks with
each heartbeat.
This project is easy to build and can be used to explore the
fascinating field of electrocardiography. There are many lessons to
be learned from the design and the methods used in this project.
