Automated Picasso Coming to a Ceiling Near You

It’s not a day too late to switch your career from engineering to art or vice-versa! While some of us tend far towards one end or the other, some like [Chris] show us just how cool it is to walk the line… er, ceiling in this case. [Chris] took a cue from his fiancée’s latest mural project to create an automated painting jig he calls ARTbOT.

Spraying the ceiling with ARTbOT sounds like fun, but it’s a dream [Chris] needed to realize with only his spare time and small budget. Constraints aside, he’s pulled it off elegantly with a cluster of extruded aluminum tubing, a few paint sprayers, and a LabView-driven Fet triggered by encoder ticks on the drop wheel. To pain the image, it’s first binarized and scaled to accommodate ARTbOT’s 8-inch pixel size. ARTbOT then gets a boost from a scissor-lift where it can then track it’s linear position with the drop wheel to spray the pixel-pattern correctly.

[Chris] pulled this rig together to help his fiancée and her art company tackle huge canvases, in this case, large freeway underpasses. With preliminary studio tests running smoothly with ARTbOT proudly printing its name, we can’t wait to see the final piece. In the meantime, have a look at this edgy handheld alternative. Watch out mural artists! There’s an 8-bit contender in the ring these days.

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The Internet of Reflow Ovens

Using a toaster oven to reflow solder isn’t a new idea. But [Sukasa] wanted something that had more features and improved appearace. So he married a Netduino, a toaster oven, and some solid state relays to made a clean-looking reflow oven. His goal was to have nothing look like an overt modification to a casual observer. Inside, however, the oven now has a network connection for system status via a Web browser or JSON.

The new brains of the oven are a Netduino Plus 2 and an I2C port expander that connects to a few extra I/O devices. The challenging I/O, though, is the heaters. When cold, the oven can draw over 16 amps, so a pair of 12A solid state relays in parallel handle that load. There are also two fans: one to keep the electronics cool and another on software control. An IGBT allows the controller to pulse width modulate the fan’s output. A pair of MAX31855s read the thermocouples that report the temperature.

lcdThe controller was a mashup of the existing oven’s keypad and an add-on LCD display (see right). One thing we didn’t see was a schematic. Of course, you can read the code and figure out how it is all connected and (unless you use the exact same oven) you are probably going to need to modify things to suit your particular setup, anyway.

We’ve seen other good looking reflow oven and controller builds in the past, including one with a touchscreen. It is also worth noting that you can find reflow ovens at relatively low prices now if you don’t feel like rolling your own.

Easier PCB Vias with Drill Trick and Conductive Ink

If you’ve ever made double-sided PCBs without professional equipment, you had to deal with connecting one side of the board to the other. You have a few obvious choices: 1) Rely on component leads to connect both sides (and solder both sides); 2) Create vias and solder wire to both sides of the board; or 3) Use through hole rivets. [Diyouware] had a different idea: use conductive ink. After a few false starts, they found a technique that seemed to work well.

This isn’t the first time we’ve heard of people trying conductive ink with varying degrees of success. The biggest problem, usually, is that the ink wants to run out of the hole. [Diyouware] has an interesting solution for this problem: Don’t drill the hole all the way thorough.

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GNU Radio Drives Oscilloscope

These days we are spoiled with a lot of cheap test equipment. However, you can do a lot of measurements with nothing more than an oscilloscope. Add something like a signal generator and you can do even more. One classic technique for frequency measurement, for example, is using a scope to display a Lissajous pattern. [Franz Schaefer] has a video showing how to generate these useful curves with GNU Radio.

As we pointed out earlier, GNU Radio doesn’t have to be about radio–it is really just a Python-based signal processing laboratory. [Franz] uses GNU Radio Companion to create blocks which in turn create the patterns on an old analog scope.

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Review: Voltera V-One PCB Printer

Back in Feburary, I was one of the first people to throw some cash at the Voltera V-One circuit board printer on Kickstarter. With an anticipated delivery date of Q4 2015, I sat back and waited. This week, my V-One arrived!

I’ll preface this article by pointing out that I do know the folks at Voltera as we went to university together. That being said, I did put down my own cash for the device, so I’ve bought the right to be critical. I also have no relationship with their company. In this article, we’ll go through unboxing and printing, then get into a review of the V-One based on what we’ve seen so far.

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Crowdsourcing Reference Designs from Github

A ton of open source hardware projects make their way onto Github, and Eagle is one of the most popular tools for these designs. [TomKeddie] came up with the idea of searching Github for Eagle files containing specific parts at Hacker Camp Shenzhen, and a method of scraping useful ones.

The folks over at Dangerous Prototypes used this to build the Github Hardware Search tool. Simply enter a part number, like “ATmega328P”, and you’ll receive a list of the designs using that part. You can then study the design and use it as a reference for your own project. You can also snag library files for the parts.

Of course, there are some limitations to this. The most obvious one is the lack of quality control. There’s no guarantee that the design you find works, or has even been built. Also, it only works for Eagle 6+ files, since prior versions were not XML. You can read more about the design of the tool over on Dangerous Prototypes.

Measuring Capacitors Over Their Working Voltage

Ceramic capacitors are small, they don’t leak, they’re convenient, but they are downright strange. Certain types of caps will lose their capacitance depending on the voltage they’re operating at. If you’re using ceramic caps for filters, DC to DC power supplies, bypass caps, or anything where you need an exact capacitance in a circuit, this can be a problem.

[Mathieu] has come up with a tool that’s able to measure the capacitance of a cap over its entire working range. He’s calling it the OpenCVMeter, and although the name might be slightly confusing, the functionality is not. This little box will measure the capacitance of a part over a voltage range from 1.3 to 15.5V.

By attaching the SMD tweezers or test clips to a capacitor, the OpenCVMeter ramps up the voltage and measures the capacitance of the part through the test cycle. This data is then dumped to a Chrome app – a surprisingly popular platform for test equipment apps – and a determination of the cap’s ability will to work in a circuit is displayed on the screen

If you’ve ever tooled around with antique electronic equipment, you’ll know the first thing to go bad in any piece of equipment are caps. Either caps had extremely loose manufacturing tolerances back in the day or the values really were that critical, but a dodgy cap can bring down everything from tube amps to computers. It’s a very neat tool, and something that doesn’t really exist in a single dedicated device.