[Open_electroporator] culture shock voltage control

Nathan McCorkle nmz787 at gmail.com
Fri Aug 10 18:29:29 UTC 2018


>From an older email to the list
"
  * below a period setting of around 300, the number of pulses given
to the repetition-counter (for the one-pulse mode to be n-pulse mode)
stop corresponding exactly with the number of PWM pulse-pairs... this
seems to be because there is a fixed delay in servicing the timer
interrupt. It could be that we need to write our own IRQ, in something
like ASM or C... something that doesn't include as much micropython
overhead as whatever generic IRQ wrapper they have setup for easy
usage.

Realistically, for this application, the last point might be moot. If
not, then I guess we might have to re-think this n-pulse mode being
the thing to do.
"

On Fri, Aug 10, 2018, 11:17 AM John Griessen <john at cibolo.com> wrote:

> Soon Nathan and I will start on using feedback to control the output HV
> levels and that will depend on other things working
> reliably, and the code will need to be carefully done to not break, or it
> can break the hardware and slow development.  The
> feedback will need to have digital filtering to ignore spikes, and a mild
> amount of feedback gain so it does not oscillate.
>
> Before we get too deep into that, I want to fix the pulse() function so it
> gives a deterministic output.
> Right now, setting up with a(54,22,1)
> pulse()
> gives 4 pulses each side, (push and pull)
>
> and setting up with a(54,22,10)
> pulse()
> gives 13 pulses each side.
>
> It's not deterministic, needs figuring out.
>
> The prototype is looking good to ship to Nathan today so he can check the
> real outputs and know these details.
> I'm looking at putting a little snubbing R and C on each switcher FET
> first, so they don't get stressed and break.
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