[Open_electroporator] Why a flyback pulser ?

[John Griessen]

On 11/11/2013 01:03 PM, Nathan McCorkle wrote:
> The HV switch the MOSFET pulser paper used was parallel MOSFETs right?

I have not read that yet.

FETs can be put in parallel to get more current ability, and one decides
bits like that later on in the process.  They get better and better and
finding buying one is an easy part of this.

Nathan, Do you get the way pulses can add at the bottom of this sketch?

http://ecosensory.com/diybio/flyback-porator-pulser-2.png

The curves are volts out vs. time.  The rising edges are not drawn quite right,
they should be like in that flyback write up fig 15 for the starting rise.
The fall time will depend on the load -- with a high resistivity load it might fall very slowly
and no need for repeated pulses if wanting a long discharge...  But assuming the load
uses up the charge, (maybe a small inexpensive cap is the reason), then
the FET can be turned on again to build up stored energy, and on release the output
will go up.  If the load is heavy and the build up time is short it won't even reach
the highest the pulser can go.  That's one way this kind of pulse generator can be used
with feedback -- as  train of pulses to get the volts up enough, and repeat
as long as wanted.  That way would have light duty parts, but versatile at
creating pulses long or short, and of a range of voltages.

The voltage pulses would have ups and downs in the long chained together pulses,
but that might even help.  The main thing I guess to keep from killing too many cells
is to keep the voltage from overshooting.