Stacking HATs for more PWM channels

Hardware, PWM, and Optics
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Hi guys,

I am looking into adding extra pumps to our setup but I am using all the PWM channels. From the “stacking HATs” blog post, stacking seems like a straightforward process but I don’t know where to start? I assume there are no off-the-shelf HATs with extra PWM channels already mounted?

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I haven’t tried either of these, or even read their docs, but might the OSOYOO PWM HAT do what you need? Or a less exact match from a bigger brand could be the Adafruit PWM/Servo HAT.

I’d love to know how you get on with this as we too are looking at controlling bigger reactors with the Pioreactor and it’s only a matter of time until we need more pumps.

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Amazing! thank you for the recommendations, I will start from there and if i get it to work i will let you know :slight_smile:

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Hi @Eleni_M
Did you have any success with either of these?

I was looking for a solution to reverse flow through the existing pumps for inoculation, and noticed that the Adafruit link I gave here is now dead (fix).

Also, I think you said elsewhere that your using larger vials - are you just using taller ones? It would be great to hear how that’s going, as various people are looking at larger Pioreactors and trying to work out best practice.

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Hi @Martin,

Thanks for following up on this thread.
I looked into your suggestions, indeed the second link didn’t work but the first one was enough to realise that this is too deep for me and it will take me too much time to get it done :sweat_smile:. I am using the Pioreactors for my work in a small startup and i can’t spent too long on this, so we will outsource it to someone who knows how to do it fast…hopefully we can post a solution soon :crossed_fingers:.
As for the larger vials, we are only using a wider vial_holder to fit our [serum bottles]. The vial volume is 100ml and the culture volume is 50ml. We use the same settings for the measuring the OD and the readings we get are not at all accurate but the normalised OD is enough for us to track the growth.
For an increased diameter it might be interesting to look into measuring the OD from underneath the vial like they do with the CGQ.

Btw i think the Pioflo setup is very cool! :slightly_smiling_face:

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Hi @Eleni_M

Sounds exciting. If you haven’t yet outsourced development to Pioreactor Inc or others, please post how many pumps you need and their general specs. I think I know some people who might be very interested in quoting for the assignment.

Either way, I’m very much looking forward to seeing your solution.

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