[Open_electroporator] Culture Shock yardboard testing

John Griessen john at cibolo.com
Mon Jun 27 16:03:20 UTC 2016


On 06/27/2016 10:28 AM, Nathan McCorkle wrote:
>> Turns ratio is just the same as open circuit voltage ratio, so car ignition coils
>> of the ordinary kind cause sparks that jump 1/4 inch, or 10 kV, so the ratio is more like 833.
>
> This seems childish, but I read what I read on a product listing, google also confirms with first hit:
> https://www.google.com/search?q=car+ignition+coil+turns+ratio
>

OK, they are 100:1, but they are not used as a transformer, but as a flyback inductor, where
the cutting off of current means the stored energy in the coil has no where to go until a
spark breakdown occurs, and at that point the primary winding is open circuit, so has no effect.
It's an energy balance problem, and yes, you were right about the 100:1 turns ratio.


On 06/27/2016 10:28 AM, Nathan McCorkle wrote:
 >> On Jun 27, 2016 7:46 AM, "John Griessen" <john at industromatic.com> wrote:
 >> Yes the all purpose one you used was able to do that huge power transfer, and it had
 >> a huge box
 >
 > No actually, it was quite small, equivalent if not less than a toaster in volume (compared to other  electroporation units it was
 > small). Also I don't care if the box is huge, more that it works and is effective and obtainable for others.

I do care about such things because they are crude and won't make a viable product.


 >
 >> We need one that does relatively more than the 2 amps during the pulse that this tested one does,
 >
 > So you're thinking 50x less impulse than the "100 amps" the commercial unit quoted is OK?

No, 2 Amps is too weak.  We will need double or triple that probably.
What reasoning/logic?
That we are not doing cap discharge, but creating a voltage that will be sustained by pulsing repeatedly
100's of times to get to the desired 1 or 5 milliseconds.  Cap discharge peaks and goes down exponentially,
so you can't have a volt level for long.  The hundred amps is not for long either, just at the peak.
With a repeated pulser, you get a long volt level that can do some change to your solution...

Another thing about the biorad gene pulser type of discharge system is it puts its own load resistor in parallel with the sample,
which keeps the volt curve uniform, but needs a lot of extra power flow, instead of it all going into the
cuvette.  We are designing an instrumented system instead of a blind one, so we can see volt curves, then see results,
and decide to change the amount of time or the voltage we subject the cuvette to.  Very different, much smaller
power needs, and makes a viable product.  Toaster sized is what I call huge, and not a goal.

You seem to be getting squeamish about my time spent and results.  If you'd like your money back that's fine, can do.

I'll be getting some cuvettes soon, and looking at available cuvette sizes and spacings.  Another way to make the system work on 
lower volts if need be is to use a closer spacing -- that will give you more field strength with the same volts on the
terminals.



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