Re: [DIYbio] A simple and cheap >100V DIY electrophoresis power supply

Guys, sorry to intervene, but just 2 cents from someone who's studies
at a university that's got "Electrotechnical" in its name.

This whole discussion reminds me of the argument from the anti-GMO
crowd. They take the theoretical worst case scenario and run it as
something that's sure to happen.
Just don't grab the damn wires. Isolating the output from the input is
a good idea and allows you to grab individual wires while being
grounded, but it's not a hard requirement. You should just know that
the device you've built is not fool-proof, and handle it with care.
And while it's not absolutely impossible, you are very, very unlikely
to die even from 380v ac, let alone 100-something volts dc.

Btw, the current limiting resistor is a terrible idea. From a quick
google search, it seems that the electrophoresis requires currents in
the range of tens of milliamps, hundreds for bigger gels. So it's just
not going to work. Even if we assume that it would require, say, 5ma,
and you limit the current to 10ma with a resistor, it means that 2/3
of the voltage will drop on the resistor, and you would need a circuit
that can output 300+ volts, which does not look like it's making it
any safer.


On Wed, Jul 3, 2013 at 7:58 PM, Josiah Zayner <josiah.zayner@gmail.com> wrote:
> Using a bridge rectifier($0.30) one can basically use AC mains voltage to
> run your gel electrophoresis. You can buy all the components for under $5.
> I tested it out and it works great. Can run a really good looking gel in
> around 30 minutes.
>
> I made a blog post here about it:
> http://doitourselfscience.blogspot.com/2013/07/a-cheap-simple-diy-electrophoresis.html
>
>
> Any questions let me know.
>
>
> Josiah Zayner
>
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