[Open_electroporator] Culture Shock yardboard testing

[John Griessen]

On 06/27/2016 02:42 AM, Nathan McCorkle wrote:
> Am I reading it correctly that the pulse, though 5msec short in
> duration, is providing 100 amps? Does that mean we need a power coil?
> Or because we know we aren't using it with a constant duty-cycle
> (should actually be relatively very low compared to normal power
> applications), can we use a lesser transformer (I guess it will heat
> up faster relative to a heftier coil)?

We are designing for 30k Ohms and have been from the start, as in "non-salty solutions".

Yes the all purpose one you used was able to do that huge power transfer, and it had
a huge box.

We need one that does relatively more than the 2 amps during the pulse that this tested one does,
because it shows a big slope, or resistance that stops the volts from shooting up quickly,
and lowers the power transferred.

On 06/27/2016 02:58 AM, Nathan McCorkle wrote:
 > It almost seems at this
 > point like you're building a DC-DC converter, but not using a boost
 > topology. I checked a few days ago and it seems car ignition coils are
 > 100 turns ratio.

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.

I just googled 'diy high current pulse' and got this
 > link which uses car ignition coils... way bigger than what we want and
 > way higher duty-cycle for sure:
 > http://www.rmcybernetics.com/projects/DIY_Devices/homemade_power_pulse_generator.htm
 >
 > Maybe it can help, or not...


I'm working on engineering which is the balance of cost and performance.  have not given up in favor of
overkill by 100X yet.  Way bigger than we want is definitely a minus for using in a product.

On 06/27/2016 03:33 AM, Nathan McCorkle wrote:
 > Another possibly helpful link for schematics or theory discussion:
 > 
https://www.pes.ee.ethz.ch/uploads/tx_ethpublications/__TPS_Optimal_Design_of_a_3.5kV11kW_DC-DC_Converter_for_Charging_Capacitor_Banks_of_Power_Modulators_02.pdf

Thanks Nathan.  Our optimization problem is to get small and light and use what we know we need,
which includes 3 kV max V; intermittent use with durations of 1 msec or 5 msec normal; total
energy transferred not so huge, but power transfer is large in order to be able to push volts into diode/capacitor clamps
that smooth the output; we can vary the pulses with a controller so we don't need to optimize steady state or worry
about DC current balance too much except for tweaking it in code if problems are noticed.  Tweaks won't be for the standard 
product though, it will be fine for well defined uses without going to any performance limits.

John Griessen