Personal Pi - Part #3

Hello everyone,

Sorry it's taken me so long to post another entry. I've been very busy with work and other things so this project had to be put on the back burner temporarily. Thankfully I had some free time this weekend to work on it, so here's a write-up for what I've done.

I last left off when I had attached the video cable and tested everything to make sure it works. The next step was to decide where to make the notches in the case for the USB and Ethernet ports on the Raspberry Pi. I placed the Pi where I had decided it should go and used a fine-tipped permanent marker to mark where I would need to cut.

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I finally picked up some cutting wheels for my Dremel so I was able to cut out the slots immediately. My Dremel skills were a bit rusty so it's not pretty, but it will work. I cut out notches on both the main part of the case and the bottom piece, to ensure I could fit the Pi completely within the enclosure.

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On my first attempt I didn't quite cut out enough, so the case could not close back up around the Pi. I trimmed a little bit more and eventually I got a perfect fit.

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Next I had to make enough room for the audio and video cables to connect to the Pi. This required cutting out a few support posts, and part of the DVD tray casing.

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Now everything is ready except for the audio. There were a few steps in this process, since I discovered my markings from my first post showing Y, R, W, and G were partially incorrect. I decided the best way for me to figure it out would be to connect the 3.5mm audio cable into my computer and send out a signal on the left channel, touch the audio conductors to the solder joints on the main PCB and note when the correct speaker produced the sound, and repeat for the right channel. I did this using NCH Mixpad, which is a free program that allows you to manipulate audio. I used a 1KHz signal out and adjusted the slider to play through a single channel. It turned out I had my Y and R markings swapped, but W and G were correct. Once I figured out which solder joint was for which channel I was finally able to solder everything in.

The audio connector:
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Soldered ground first:
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Using my laptop to produce the audio signal for testing:
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Finally soldered together:
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It's certainly not pretty, but I'm not going to worry about it.

Now that we have audio, it's time to test it again. I don't have the power circuitry for the Pi mounted yet, so I ran my cell phone charger cord through the DVD tray in to the Pi to power it. I used my homemade 12v power supply to power the rest of the circuitry.

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Success! Still powers up!
In order to test the audio, since I don't have internet hooked up to this thing yet, I decided to make a very simple Scratch sketch to make noise in an infinite loop. I figured this would be a good way to test and make sure the speakers still work.

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I didn't take a video, but there is, indeed, audio coming from the speakers. Looks like everything's working as expected!

That's pretty much it for now, probably more pictures than text on this one. The next entry will cover the creation of a very basic voltage regulation circuit to power the main board and the Pi from a single power source. I hope you enjoyed this entry, as bland as it may be, and as always thank you for reading!

<-- Return to Part #2