Controlling Cheap, Awesome Christmas Lights

[James] was wandering around Walgreens after Christmas and found something very interesting – RGB LED Christmas lights that were individually addressable. At $6.50 for a strand of 15 lights, he just had to buy a few and figure out the control protocol. After all, who can turn down a big, cheap, controllable RGB LED strip?

The packaging for these lights – apparently manufactured by BriteStar - includes a ‘try me’ button that cycles through different light patterns. This button is what initially tipped [James] off to the fact the lights on this strand could be individually controllable. Opening up one of the lights, he found exactly what he wanted: an epoxy blob, two wires for power, and three wires for the signaling.

After checking out this light with a scope and logic analyzer, [James] realized there was a very, very simple protocol going on. Essentially, the entire string functioned as a gigantic shift register, taking the values for one light and pushing it down the string. In looking at the protocol, [James] also discovered] these lights support 16 levels of brightness. Yep, RGB LED Christmas Lights with PWM for under $7. Can’t beat that.

[James] wrote an Arduino library to control these strings and put it up on Github. While your local Walgreens has probably already hidden these lights away in the back of the store, it might be worth asking around to see if they have any left.

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Homemade Polariscope is Super Easy to Make

[Abhimanyu Kumar] was watching YouTube videos one day when he came across something called a Polariscope — After learning how it worked, he discovered you can make your own using household items!
First off, what is a Polariscope? Well, put simply, it is a device that can show you the photoelasticity of a clear specimen, which can reveal the stress distribution in the material! And it is actually really easy to make one.

All you need to build your own is:

• A polarized light source (any modern LCD monitor)
• A transparent specimen (plastic cutlery, glass statues, plastic you can bend, etc)
• A circular polarizing filter (the cheap 3D glasses you didn’t return at the theater)

Then just place the objects in the order shown in the diagram and start snapping some photos. This would be really cool for checking stress concentrations in a project — provided you are using some Lexan or acrylic!

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Paintball Pistol Turned Sniper Rifle

There’s a huge price discrepancy between paintball pistols and paintball sniper rifles. So the [Fresh-Prints-of-3D] decided to print himself an sniper upgrade kit. He started with the classic Tippman 98 Custom pistol , which is a tried and true industry standard when it comes to reliable paintball guns. Using Sketchup he designed a side loading hopper adapter, a fixed stock, a magazine adapter, various brackets, and even a bipod fore-grip.

He then printed the parts out at his local hackerspace; Innovatrix Labs, which is in Northeastern Pennsylvania. A Portabee 3D printer was used for some of the first prototypes but the final parts were all printed on a large MendleMax2 which has a build area large enough for the entire fixed stock! The best part? He’s only been using SketchUp for a few months. Once the design and build is completely finalized he might release it under a CC license. 

It just goes to show that 3D printers are really breaking down various markets of overpriced plastic components — 3D printers only print trinkets? Pfft.

[Via Reddit]

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Clever Reed Switch Catches Thief

When [Abhimanyu Kumar] noticed money going missing from his small bookshop, he decided to set up a little trap to catch the thief. The problem was that the bookshop’s money was stored inside a cupboard in their house (back end of the shop), which meant that the culprit was likely one of their own employees. They already have a CCTV system installed in the actual store, and although he could simply add another camera in the house, [Abhimanyu] didn’t really want to do that.

He instead devised a simple security trap: dubbed the Jugaad Security System. In Hindi, Jugaad quite literally means “hack”. He added a small magnetic reed switch to the cupboard where the money is stored—well, was stored—which is then linked directly to an intervalometer. This then connects to an inconspicuous DSLR sitting on one of the work benches. He aimed the camera at the cupboard and, in case the lights are out when the system is tripped, set it to an extremely high ISO.


Three days later, during an especially busy day at the store, the camera snagged a few images of their would-be thief. Unfortunately, it was one of their own employees. A quick call to the police later and the thief confessed, returning the stolen money. Needless to say, they fired him.

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Porting Contiki to the TI MSP430 Launchpad

For many years Contiki has been one of the main choices when it came to choosing an IPv6 over Low power Wireless Personal Area Networks stack (aka 6LoWPAN). It is developed by a world-wide team of developers with contributions from Atmel, Cisco, ETH, etc… and is open source. As most platforms to which Contiki has been ported are quite expensive, [Marcus] decided to bring the operating system to the TI Launchpad. For our readers that don’t know, the latter is based on a msp430g2452/2553 microcontroller, which only have 256/512 bytes of RAM and 16kB of ROM. As a side note, Contiki typically requires 10k RAM and 30k ROM.

[Marcus] therefore had to remove several features from Contiki: queue-buffering, energy estimation and regrettably uIP. His test setup (shown above) uses the TI CC2500 radio that can be found for less than $2 on Aliexpress, for which he wrote radio drivers from scratch. He also coded his own radio duty-cicling layer, as the one included in Contiki was too big.

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Mooshimeter: The ‘Why Didn’t I Think Of That’ Multimeter

Despite how useful multimeters are, there are a lot of limitations you just don’t think about because they’re the way electronic measurement has always been done. Want to measure voltage and current simultaneously? Better get two meters. Measuring something in a dangerous, inaccessible, or mobile place? You could rig up a camera system to show the meter’s display on a monitor, you know.

Mooshimeter is the better way of doing things. It’s a multichannel multimeter that communicates with your cell phone over a Bluetooth connection. With two channels. the Mooshimeter makes it easy to graph voltage against current to plot a beautiful IV curve on your smart phone.

Being a wireless multimeter means you can stick the Mooshi inside a robot and get instantaneous feedback of how hard you’re driving your motors. Far from being a two-trick pony, the Mooshimeter is actually a pretty good multimeter by itself. It can handle 600V and 10A with 24 bits of resolution. Here are the complete specs. The Mooshimeter is available for preorder here for $100 USD.

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Superb Open Source CNC Laser Cutter

The Open Source movement sets another fine example with this superb 2-axis laser cutting/engraving station.  This is version 2.0 which has a more compact size measuring 12” x 20” x 4”. The DIY laser cutter/engraver has a manual vertical axis but you can opt-in for a digitally controlled one.

The electronics as well as all moving metal parts have been designed keeping simplicity and strength in mind. The neat thing about this laser cutter and engraver is that it could give commercial CNC machines a run for their money.

What’s really handy is that Open Source machine has a large community behind it. Head to the Buildlog.net blog and join the forum to view all drawings, schematics, build instructions, and source files that are available for free.

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