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Experimenting with Electrocardiogram Electronics

ChelseaBack
5
Trainee Electronics Engineer, currently studying towards my degree in Electronic Engineering at the University of Hudderfsield. Completed my HND in Electrical & Electronic Engineering from Bradford College 2017. Love to try new things and build interesting projects!

Comments

August 22, 2017 11:50

Please NEVER use this connected to a laptop or other mains powered device. Generally laptops etc use a floating earth, so what may be zero and +5V on a USB pin is really say 120V and 125V relative to ground. Put that across someone's chest and it can kill them, 9uA through the heart when it's in the ST phase, will stop it forever!!!

Anything connected to the body should be battery operated and only connected back to something mains powered through optical or other isolators.

0 Votes

August 22, 2017 11:50

@stevekennedyuk -- That is 100% incorrect. The Power supplies used on laptops are required to be isolated to a minimum of around 1500 Volts in order to meet UL, CE and other specifications.

August 22, 2017 11:50

@JLRTX If the laptop has a mains connector with ground a connection, and the user uses an outlet with no ground connection, a current from the mains filter capacitors with an amplitude of half the mains voltage will be available at the laptop connections. The short circuit value of this current to ground can be 375µA for non medical equipment. This meets UL 1283, CSA 22.2 No. 8 1986, IEC/EN 60939.

August 21, 2017 12:40

Where can I get this kit?

August 21, 2017 12:49

@leonrussell99 Found it available here: https://www.crowdsupply.com/signal-lattice/bes-afe-1

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