[Open_electroporator] culture shock micropulser code needs changes

Nathan McCorkle nmz787 at gmail.com
Wed Jul 26 17:03:55 UTC 2017


The code I wrote definitely uses the timer peripherals. I did all my
testing with aa 30kOhm load, it can get 10X past 700volts. Not sure what
you're looking at, but sounds like you need to play with different
settings. Just write a small program to sweep the parameters to the "a"
function, then plot the output voltage. In a previous post here I showed
how I did such.

This is from a past message, and only sweeps one parameter:
ef n():
  for x in range(12):
    v=x*200
    a(3200-v, 150, 6) # period, width, number pulse-pairs
    pulse()
    pyb.delay(6000)

On Jul 25, 2017 6:40 PM, "John Griessen" <john at cibolo.com> wrote:

> There is a little problem with loading I saw just now,
>
> If Mitchell's cell suspension in a 1mm cuvette measure less than a mega
> Ohm resistance total across the contacts,
> we will have to do something before he is ready to test.  See below.
>
> For more salty solutions I just noticed there will be a big drop compared
> to my earlier testing
> probably because of the new program not using timers for the push and pull
> pulses to keep them
> as precisely equal as possible.  I will be taking some of the nice
> functions Nathan coded
> and moving them over to work with my timer-based pulser code, so the
> pulses are as equal as possible
> and the currents can go up with as low as a 30 k Ohm load, as the early
> program does.  Nothing
> else changed, so the different programs are the prime suspect in this
> different outcome I got
> just now.  I noticed that when I reduced the period between pulses below
> 50, the output dropped
> even if the number or width of pulses was large.
>
> When I put a 33 k Ohm resistor across the output, and tried various
> combinations of
> pulse period, width, and number, I could barely get more than 700V out of
> it.
>
> So, to go back to being able to deliver 120 Watts of power for a short
> while, (and widen the range of
> types of cells and buffers that can be electroporated), I will be testing
> with the old code again,
> and adding the nice pulse() and a(period,width,number) functions to it.
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