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Thermostat Deployment

Posted 2011.03.19 17.09 in Computers/Internet/Technology

Today I went ahead and did it.

There were just two things left to fix and I fixed ’em both. One hardware glitch and one software bug.

That’s it. Done deal. The thermostat is live and installed.

It’s ugly and there’s wires all hanging out of it and it looks like a high-school science project and I don’t care – it works and it’s networked and it does exactly what I want, when I want, how I want, and I built it from scratch!

Now if I’m cold at 2am I don’t have to get out of bed and crank the heat – I can grope around for my laptop or iphone or ipad or whatever is nearby, log into the thermostat and twiddle the dial remotely. I’m almost looking forward to being cold in the middle of the night.

Or hot – come summer, I’ll have just as much control over the A/C as I do the heat.

Isn’t it wonderfully ugly? The red things in the wall are plugs from a previous thermostat. Apparently it was there way back when the wall was last painted, some 9 or 10 years ago.

The red glow on the wall indicates that the furnace is currently on. If the A/C were on, there’d be a blue glow up there. No glow indicates that we’re at the desired temperature.

The thumbnail pic on the left shows a better view of the thermostat in situ in my livingroom. All dangly wires and protruding bits, hanging out for all the world to see. Like it has no shame.

I’d love to share a schematic with you all, but I didn’t make one. The guts are one messy tangled mix of design-and-build-on-the-fly-and-hope-it-works. There’s no internal photos for the same reason. It’d just shock and offend.

I will share the source code though – for those willing to give this a shot yourselves, there’s enough comments in the code to explain how to build the physical side of things. Well, most of it anyways. The rest, you can extrapolate for yourselves.

As mentioned in earlier posts on the subject, it is based on the Arduino IDE, although there’s no actual Arduino inside. The heart of it is a repurposed Serial LCD Kit from SparkFun. It just happens to be a small footprint Arduino-compatible board designed to fit behind a 16×2 LCD display. (updated 1104.18)

Like it’s an Arduino without the Arduino, the network side of it is an Adafruit Ethernet Shield, only without the Adafruit ethernet shield part. That is, all the thoughts and purpose and intent from the Adafruit shield is there, but to save space I didn’t actually use her shield in the final product. Just the Wiznet module, hotglued to the inside of the enclosure.¬†Oh but it is an Adafruit Arduino enclosure, so there you go!

Anyhow, babbling aside, here’s the source code! There’s some extra features I haven’t talked about yet, and some stuff that hasn’t been implemented yet in hardware. And it’s been shelved long enough that I’ve forgot how to use half the functions. And there’s no documentation, naturally.


Home Made Camera: Update

Posted 2009.10.12 10.29 in Hobbies, Photography

So after all the excitement on Saturday of taking and processing pictures from my home-made camera, yesterday I sort of settled down and evaluated.

Pinhole shots are expected to be ‘soft’ but my shots were too soft. I asked around, and it was suggested that the hole I was using was too big. I wasn’t sure how to measure things that are in the less-than-millimeter range, but then I got an idea – I’d use my negative scanner, and scan at a super-high resolution, then just count the pixels of the hole.

It worked, and also provided a very good enlarged view of my pinhole – not only was it too big, it was a mis-shapen mess! The pinhole equivalent of trying to take pictures with a lens that was cracked and scratched all over. No wonder my shots were so ‘soft’ aka blurry.


You can see in this comparison, the left side is the pinhole I was using on Saturday. Yuck! The right side is a new pinhole I made, that I’ll use on my next roll to see how it goes. It ought to be much sharper. The funny thing is these pinholes were both made with the same pin, in the same piece of aluminum – just obviously I was way more careful on the second one.

On the camera itself, I also finished up some more work on it yesterday – I decided that the winding knobs are good enough so I finished them off, I have a simple but effective mechanism for holding the back in place, and I added a second ‘shutter’ that hopefully will work in tandem with the pinhole – i.e. allow me to open and close the aperture without moving the camera around too much.

Camera Front

Camera Front

Here is the face of the camera. The knobs have been finished off, and I’ve added a new shutter mechanism for the pinhole module.

Closeup of Pinhole

Closeup of Pinhole

The pinhole is punched in a razor-thin piece of aluminum, I’ve actually got three different holes in the aluminum so I could move it around and select the different holes. The aluminum is held in place by the brass strap, which is coated with black felt at the back.

The shutter is another piece of brass which rotates up out of the way. The pivot point has two washers and a spring, which allows me to adjust the tension while still keeping it tight. It too has black felt coating its back. There is a brass ‘pin’ to stop the shutter at the right point when it is closed.

Camera Back

Camera Back

The back of the camera is held in place by a fairly simple system, although I could improve it later. At the bottom of the camera I added two small bits of wood to hold the bottom of the back, and towards the top at the sides I drilled two very small holes, and just have a pair of brass nails that slide in and out, to hold the upper part of the back in place. I added another brass nail as a ‘handle’ to help extract the back once the sliding nails are out of the way.

The process of taking pictures is wonderfully complicated: First you set the camera in position on a tripod or whatever, angle it as best you can. There’s no view finder, just point and hope. It is a ‘wide angle’ so it will capture quite a bit of the scene. Second, you slide up the darkslide / safety shutter, after ensuring the pinhole shutter is closed. Third, rotate the pinhole shutter to the open position, being careful not to jiggle the camera.

Count off the exposure time, then rotate the pinhole shutter to the closed position. Fifth, slide the darkslide / safety shutter closed. And finally, crank the film advance knob while looking through the back window, to get the film to the next frame.