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

On 7/4/13 4:10 PM, Alexey Zaytsev wrote:
> They take the theoretical worst case scenario and run it as
> something that's sure to happen.

You can do anything you like, supposedly. If you've been thru any lab
safety class then you know there's many things which are recommended not
to do. Does it mean they'll all occur - no - they are best practices.
I wouldn't use a bunsen burner in a small closet without any ventilation
for example yet you might insist that you want to - whatever - that
doesn't make it a good practice or allow any justification that "oh,
it's okay! I do it all the time!". I wouldn't add agar to water and put
in a microwave unattended to boil for several mins and then remove
immediately. You know why, right? Yet this discussion has begun to
split hairs, about what is and isn't safe, even if all the information
is freely available with a little looking around. There are a lot of
things which are common sense after basic education of what not to do.
Should we have a long discussion about thousands of them or suggest
people to do a little bit of basic homework first. I suggest the
latter. Especially if the former has already failed to yield much other
than stubborn answer-backs. Do we want some newbie to get hurt and
their parents call the regulators and then talk of regulation starts up
again? Um, no way. Should bad ideas be kept on a web page for others
to similarly try bad practices? I suggest not. You mention GMO
scares, well, that just shows how paranoid the public and/or regulators
can be related to anything mildly scientific looking, yet still you'd
like to stick to less-great practices which might add safety risk? Not
a great idea.


On 7/4/13 4:42 PM, Alexey Zaytsev wrote:
> Ok, I've actually looked at the original article.
> Don't ever build anything this way.
How many votes will go this way, I wonder. ;-D LOL!
> But add a switch and a fuse, build
> it a lot less flimsy, put it in a plastic case,
2 fuses and a PTC at least and it's still not a good idea as I suggested
before. Putting it in a case is still not that safe since the buffer
on the table is always a part of the electric circuit.

> and it's not all that
> much unsafer then a commercial power supply.
>
Guaranteed that the commercial supply will have current limiting. Or it
couldn't be sold commercially, period. A Zener is a simple method of
current limiting but may not be cheap, a feedback circuit is better. At
which point, building the circuit homebrew to save time and money is
questionable, although it still has great educational value.

## Jonathan Cline
## jcline@ieee.org
## Mobile: +1-805-617-0223
########################





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