Monday, July 29, 2013

Kitchen PC: The Hardware

Part of the reason I decided to resurrect this blog was I had a cabinet full of old computers, internet appliances, and AV equipment that I wasn't using, but they work well enough that I really didn't want to dump them in the e-waste.  A couple weeks ago or so, I decided to adapt an old tablet computer to be an under-the-counter kitchen PC. My goal is to have a PC in the kitchen that I can use to control a whole-house music system. I suspect with this project the software is going to change more frequently than the hardware so I am going to divide posts on this project along those lines. I'll talk about the my generation one hardware configuration here, and my first stab at a software configuration in a later post.

This isn't my first attempt at a whole house audio system. I have had some of the music nodes active, at least I have played around with them previously, but in order to play anything I had to go to sneak into the den where the general use computer resides. This is decidedly a low WAF technique. For a while I was using a remote control app on my phone to control the music on my den PC, but this was annoying for me, especially since that computer was often tied up doing other things. I could stream directly from my phone to a single music node, but in order to stream from your phone to multiple nodes, at least using an Airplay based system, you need a PC committed to the task. When I started brainstorming this project, I thought I would hide a PC in the laundry room, pantry, or on top of the kitchen cabinets, but since I was planning on adapting a tablet I thought it might be useful to try to take advantage of the screen rather than hide it and mount it underneath the cabinets and actually use it as a kitchen PC. The spot next to the refrigerator was good since I wasn't exactly sure how this would look and that spot is normally a mess anyway.

Starting materials

The tablet PC I am using is an HP TC4200. I bought this PC of Ebay for about $100 several years ago, when it was already obsolete, for my wife to use for her lectures when she started teaching. I spent another $50 or so on more memory, a new hard drive and (I think) a new battery. She used it for a year or two before she was able to get a new tablet PC. It hasn't done much since then except be my guinea pig.  

From PC Magazine (this tablet PC was quite expensive, back in the day)

The audio nodes are based around first generation Airport Express units. As I mentioned before, I have a few of these. I used them as both a router and an access point over the years as well as units to just serve as Airplay nodes, but recently they found themselves in the future e-waste cabinet. For reasons that aren't clear to me, they seem to develop problems working as a wireless router or access point. It turns out that even when these units are no longer ideal as a reliable access point, they can still work fine as an Airplay output node, especially if you operate them wired into the ethernet network. I've been trying them out in this capacity. Streaming from one of our i-devices to an Airport Express set up in the kitchen.

From Gdgt

For each audio node I would like to have a decent amplifier and speakers. For the amplifiers I'm planning on using T-class units. I already have 2, a Dayton Audio DTA-1 and a Lepai LP-A68. For the speakers I am planning on using pairs of Dayton B652. I have two pairs of these already one of which I am using and the other I am planning on swapping out from another location. I purchased these all from Parts Express. For future nodes my plan is to use Lepai-2020A+ for the amplifier, although I may swap out the amplifier attached to the PC with a higher quality USB soundcard/amp, perhaps a Topping TP30. I'll also try to find smaller, higher quality speakers. I think I may swap out the Polk RM6751 speakers in my theater for something else (thinking Pioneer SP-BS22-LR) and use them around the house.

Initial placement

As I mentioned before, placed the tablet PC underneath the cabinet, next to the refrigerator. The nice part about this arrangement, besides being out of the way, is that when the screen is fully closed, the pc is almost totally hidden from view. Initially I mounted the computer under the cabinet similar to this Lifehacker inspired post using two coat hangers held in place by two shelving screws, but this prevented the screen from folding up all the way, which I didn't like. For my second attempt I used four pieces of 4"x2" industrial strength Velcro, to hold the computer in place, two on each side of the computer. Before attaching the Velcro pieces to the computer I cut them along the access panel seams, in the unlikely event I want to change out the hard disk or the battery. At first I was concerned the PC would fall down during the 24 hours it takes for the adhesive to take hold, so I tried to use some fishing wire tied around the leftover screws to strain relief the velcro. It turned out this wasn't necessary and the Velcro adhesive worked fine without any additional support.

The power brick plugs into the PC in the front, on the side toward the user so I had to reposition the computer on the velcro to make room for the cable and the backside of the lower lip of the cabinet front. I put the power brick on top of the refrigerator underneath the cabinet so it is out of view and plugged it into the outlet behind the refrigerator. I used some masking tape to keep the power cord out of view, but I will probably come back to this with a better solution. The audio amplifier and speakers are top of the cabinet. They are mostly hidden from view but from some vantage points you can see the speakers (part of the reason I'd like to replace them with smaller speakers). I drilled holes through the bottom and top of the cabinet over the refrigerator and routed a power and audio cable to the top of the cabinet. The audio input of the PC is a 3.5mm mini connector (like a headphone jack) and the amplifier has left and right RCA inputs, so I used a long mini-to-mini cable, a mini stereo union, and 3.5mm mini-to-RCA Y-cable to connect the two, although if I had a long enough Y-cable around I would have used only that. The 3.5mm jack is on the side of the computer away from the refrigerator so I routed the cable along the back of the cabinet and again held it in place with tape. I'm still playing around with the best way to do this. I want to keep the cable hidden but it keeps getting in the way of the latch when I try to open the folded-up screen. I may try to route it around the front of the PC as well.

Here's the alcove with the kitchen PC with the screen closed. I should really clean this area up.

Here's the kitchen PC screen open.

That's the starting hardware configuration. I'll talk about the software configuration in a later post. Maybe I'll clean up the pile of paperwork too!

Upgrade ideas
1.  Better speakers.
2.  Integrated USB sound card and amplifier combo.
3.  IR receiver to control with a traditional (i.e. non-iPhone remote).
4.  USB notifier light, something like this. I'm not sure exactly what I would want it to tell me, but I think this would be straightforward to do.
5. Integrate with a motion activated camera to log who comes to the front/back doors.
6. I wonder if I could use this PC as a bluetooth speaker phone?
7. USB thermometer and/or humidity sensor to display or track indoor temperate.
8. Wireless USB thermometer or weather station to display and track outdoor weather info.

Update! (8/2/13)
My first take on the software configuration for the kitchen PC is here.

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