[Open_electroporator] Introduction

NeonJohn jgd at neon-john.com
Wed Mar 12 03:00:41 UTC 2014



On 03/11/2014 07:45 PM, John Griessen wrote:
> On 03/11/2014 05:07 PM, NeonJohn wrote:
>> Nathan McCorkle asked me to come here and discuss my HEI ignition
>> coil-based high power, high voltage driver.
> 
> Hello NeonJohn,
> 
> Thanks for spending some time on this.  Nathan sounds like he's going to
> put some time into
> making an electroporation machine that can copy some of the $4000 models
> functions that Wall Street backed bioengineers and university
> researchers usually
> operate with.

I'll have to admit that I had to go to Google to find out what
electroporation is.  Interesting.
> 
> It's been a while since I thought about this.  One of the functions of
> the "usual machines"
> (what was that brand name machine again Nathan?) is to zap a low
> conductivity
> sample that is how big physically?  I just looked at the archived back
> and forth we did with
> this elist last November and could not find cuvette size.  So, the low
> conductivity zap
> is 2kV and a spike is OK in comparison to past experimenters's results,
> and you could
> make it with a flyback converter as in:
> http://ecosensory.com/diybio/flyback-porator-pulser-2.png
> and it all could be small.

If I may try to read Nathan's mind, I think what he is interested in is
the circuit itself and not the driver.  One could use a much smaller
IGBT or power FET and say a 6.3 volt filament transformer operated in
reverse, for example.  With perhaps 24 volts in to the HVDC input, the
transformer would make a few thousand volts.

If the transformer primary could not stand the voltage as-is, it could
be VPI (vacuum-pressure impregnated) with 100% solids epoxy varnish.  We
use that technique to ruggedize the transformers in Fluxeon's induction
heaters.

Another approach would be to wind your own around a ferrite core (we
sell a selection of cores to hobbyists at Fluxeon).  One of our
transformers uses 9 turns on the primary and 50 turns on the secondary
and generates 1500 volts at a couple of amps at 80kHz and yet one can
almost close his hand around it.  That ratio would be about right to get
5kV or so in the flyback mode with maybe 45 volts in (Meanwell makes a
very inexpensive fully enclosed 45 volt, 8 amp supply that we use
extensively).

Just pointing out some of the possibilities of the circuit when NOT
using an ignition coil.

> 
> So, that first application is easy, but Nathan just adds more requests
> as soon as you say
> something is easy, until it is hard, dangerous and expensive :-)

Yep, that's an engineer for ya!

> 
> I am wanting to develop a kit with web instructions and disclaimers that
> will test the waters
> for a normal assembled product that is safety tested for lab use and buy
> product liability insurance
> and make and sell it.  The assembled tested version could be years
> away.  The kit should be small
> and weigh 3-4 ounces except for a DC wall wart of another 2 oz.  

We looked at getting agency approval for our Roy induction heater.  $10k
from ETL and $15k from UL just to set up the test and write the test
procedure.

Product liability was a similar sticker shock.  So I use the best
available safety techniques and we go without.  One of the many risks an
entrepreneur takes.

The UL listed wall wart and not worry about the rest of the stuff is the
way to go.  BTW, my little board just draws about 5 ma at 15 volts and
most of that is the relatively high powered gate driver.  Drop the logic
voltage to 5 volts (4000 series logic doesn't care), use a logic level
IGBT or FET and now you're talking about wall wart territory.

Anyway if I can be of assistance, I'll hang around for awhile.

John


-- 
John DeArmond
Tellico Plains, Occupied TN
http://www.fluxeon.com      <-- THE source for induction heaters
http://www.neon-john.com    <-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
PGP key: wwwkeys.pgp.net: BCB68D77
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