Repair Job Fixes Compressor, Gets it Online

We’ll never cease to be amazed at the things people try to put on the Internet of Things. Some are no-brainers, like thermostats, security cameras, and garage door openers. Others, like washing machines and refrigerators, are a little on the iffy side, but you can still make a case for them. But an IoT air compressor? What’s the justification for such a thing?

As it turns out, [Boris van Galvin] had a pretty decent reason for his compressor hacks, and it appears that the IoT aspect was one of those “why not?” things. Having suffered the second failure of his compressor’s mechanical pressure switch in a year, and unwilling to throw good money after the $120 that went into replacing the first contactor, [Boris] looked for a cheaper and more interesting way to control the compressor. An ESP8266 dev board made interfacing the analog pressure sensor a snap, and while he was at it, [Boris] added a web interface with a nice graphical air pressure gauge and some on-off controls. Now he can set the pressure using his phone and switch it off in the middle of the night without going outside. That’s an IoT win right there.

No air compressor? No worries — build your own from an old fridge. The non-IoT kind, preferably.

Cheap and Effective Dune Buggy Wheel Chair

[masterfoo]’s mother-in-law suffers from a bad hip which would have sidelined her participation in the Fourth of July festivities. As a testament to the power of family and ingenuity, [masterfoo] built her a beach-capable wheel chair to give her some off-roading capability.

The frame is built out of 1.5″ PVC piping and the tires are 20×8-8″ inner tubes for ride-on lawnmowers. The lawnmower  wheel inner tubes were cost-effective and fit the purpose, saving the need for the more expensive purpose-built-for-the-beach Wheeleez tires. They also have a fluid inside that plugs small punctures which will come in handy against he beach’s small cacti and other flora. This video was their guide for the foam insulation and plywood wheel assembly, also employing the handy man’s secret weapon to protect the tube from the rim’s plywood edge. Check it out in action!

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Arduino Makerbeam Live Plotter Controlled By HTML5 Canvas and Java Website

We’ve never seen someone build a plotter out of buzzwords, but [roxen] did a really good job of it. The idea is simple, place the plotter over a sheet of paper, open a website, draw, and watch the plotter go. Check out the video below the break.

The user draws in an HTML5 Canvas object which is read by a Java Web Server. From there it gets converted to serial commands for an Arduino which controls the steppers with two EasyDrivers.

The build itself is really nice. It perfectly meets the mechanical requirements of a pen plotter without a lot of fluff. The overall frame is T-shaped, for the x- and y-axis. The movements are produced by two steppers and acetal rack and pinion sets. The pen is lifted up and down by a hobby servo.

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Mix your own photo developing emulsions

If you’re into developing your own photographs you might try mixing your own emulsion. [Jimmy Hartnett] worked out the chemical reaction necessary to make a photosensitive medium using Silver Chloride. His process lets him manufacture canvas that can be use like photo paper. The gist of it involves coating the back of a canvas with Gesso to prevent the emulsion from passing all the way through. He then floats the canvas face-down to apply the emulsion and skims it with a straight edge before it has time to set. You can see the results of some contact print testing in the image above. If anything, this makes a great piece of art to hang on the wall as it’s visually interesting and [Jimmy] has a personal connection because he not only made it himself, but came up with the process.

Remote image processing in JavaScript

[Tom] wrote in to tell us about his JavaScript project for motion detection. It ties together two ideas we’ve talked about recently. The first is doing image processing in-browser using Canvas(), which we’ve seen employed in captcha breaking. The second is offloading heavy processing to browsers, which we saw recently in the MapReduce implementation. [Tom] is using JavaScript to compare consecutive images to determine if there’s any motion. He did this as part of MJPG-Streamer, a program for streaming images from webcams. It can run on very limited hardware, but image processing can be very intensive. Doing the image processing in-browser makes up for this limitation and means that a custom client program doesn’t have to be written. You can find the code here and a PDF about the proof of concept.

Simulated annealing


Here’s an update on our earlier post about genetic programming. Altered Qualia has posted a new implementation of [Ron Alsing]’s idea. It starts with 50 polygons and then randomly changes one parameter with each optimization step. If the the change results in fewer differences from the target image, it’s kept as the new best DNA. This search method is similar to simulated annealing. The image above is the result of 1500 good mutations out of 35900 possible. The implementation lets you choose any image, but smaller means the fitness calculation is faster. It’s written in JavaScript using the <canvas> environment. You’ll definitely get better performance using newer browser builds.

[Original image by R Stevens]

[via Waxy]