Pneumatic Controller: Part 7

Some people, like myself, really like when things fit really nicely together and everything’s all organized. This post will be good for those people, especially after the makeshift stuff I’ve been using until now. We begin!

I needed to find some way of attaching the pistons’ ribbon cable to the Arduino. For the sensors, I used the wire itself (their wire was thicker/stiff enough) but the ribbon cable can’t do that. Also, it’s a lot weaker/uglier.

Ugly and weak

Weak and ugly

Last time I tried attaching ribbon cable to headers, I wrapped each wire around the header and soldered it into place. While this worked, it was time consuming and messy. This time I decided to use some leftover female header, having found that I could put the wire into it, then press everything together using male headers, securing it with glue.

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DSCN2138This worked much better/neater, although still rather annoying. Eventually I figured out how to do it correctly, but that’s for later.

Next up was mounting the Arduino in place. I wanted something sturdy that would be secure in the long term, but could also be quickly removed in case I needed to change something. Conveniently, there was a metal rail near where I wanted to be, which meant I could use those plastic clippy things (so helpful!).

The Arduino needed to be mounted to something first so I cut a scrap piece of wood and drilled holes to line up with ones I made in the clippy thing.

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Then I drilled holes to line up with the ones are are pre-made in the Arduino for mounting purposes. The Arduino also came with little plastic pieces to help with mounting, so I put a little hot glue into the holes and pressed the female ends in.

 DSCN2145 (1) DSCN2146Then I used the pins to hold it together. Everything fit nice and snug.

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To power the Arduino, I had an AC cable. I didn’t want the Box to have two separate plugs, so I planned on using the same power the Box was using. The Box took in the AC power and connected it to a transformer that would give the 24V output the solenoids/sensors needed. My plan was to connect the Arduino adapter to the same input the transformer had.

First up was to attach wires to the Arduino adapter in a safe way. I could have opened it up, but I figured that someone may want to change it in the future so not cracking open the plastic was better. I found some thick wires and wrapped them around the tongs of the plug with some heat shrink tubing. Heat shrink tubing is rubber tubing that will shrink when heat is applied (surprise). It’s very helpful for keeping wires covered and safe, since it’s held in place by the pressure of trying to be smaller than the wire inside of it is.

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After adding some hot glue for structure and applying heat, I had a strong safe connection that also looked very nice.

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To attach to the transformer, I lucked out. All wires in and out were screwed in, so all I had to do was screw the existing wires in with my additions.

Before

Before

After

After

Then I wired up everything and did some test runs. Unfortunately, for one of these tests I confused the power sources and accidentally connected the higher 24V source to the LCD, which promptly shorted out.

As annoying as this was, it did show me how confusing things were becoming with wires, not to mention that the wires I had been using were stiff and unwieldy. I decided to upgrade.

First was to switch to ribbon cable, which is much more flexible. I figured there must be a better way of attaching it, so I did what I should have started with and googled the problem. What I found is that the best way is to tin the wire and the header, then heat them both and let them melt into each other, finishing with a layer of glue for structure. It worked beautifully.

At least compared to what it was before

At least compared to what it was before

To help keep the wires coming from the lid tidy, I mounted a piece of thin board on the edge and drilled some holes for zip ties.

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To wrap things up, here are some pictures of what things are looking like now.

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Sensor circuitry

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Everything’s going smoothly, plus or minus a few hiccups. Tests have been mostly successful and Part 8 should be done decently soon. It will probably be the second to last one.

Until next time,

Ari

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