Sending Data Over Bluetooth Low Energy With A Cheap NRF24L01+ Module

September 21, 2013 by Mathieu Stephan 30 Comments

nRF24L01+ modules like the one shown above are a great way to send data wirelessly between your projects. They can be found on many websites for less than $1.50 a piece and many libraries exist for them. After having thoroughly looked at the Bluetooth Low Energy (BLE) specifications, [Dimitry] managed to find a way to broadcast BLE data with an nRF24L01+.

Luckily enough, BLE and nRF24L01+ data packets have the same preambles. However, the latter can’t send more than 32 bytes in a packet and can’t hop between frequencies as fast as the BLE specification wants. [Dimitry] found the solution when he discovered that he could send unsolicited advertisements on three specific channels. In the end, considering the 32 bytes the nRF24L01+ can send, you’ll need to use 3 bytes for the CRC, 2 for the packet header, 6 for the MAC address and 5 for devices attributes. This leaves us with 16 bytes of pure data or 14 bytes to split between data and name if you want your project to have one.

Haunted Dollhouse Microcontroller Networking For World Maker Faire

September 21, 2013 by Mike Szczys No comments

master-slave-networks

It’s pretty awesome to get see the number of projects presented at World Maker Faire. But we still love digging into the gritty details that only an in-depth build post can deliver. Here we get both. You can see the circuits pictured above in the Circuit Castle exhibit at WMF this weekend, and you can read about how the microcontroller network was built in [Jim’s] article.

As the title states, this is a network built for a dollhouse. Each slave device performs a different task; adding color, sound, motion, and interactivity using some sensors. The post discusses the i2c (or TWI to get around licensing issues as [Jim] mentions) communications used to talk to the ATtiny85 chips on the slave boards. Because the eight-pin package leaves few I/O pins to work with an ATtiny84 was also added. It brings 14-pins to the party, including multiple ADC inputs for reading sensors.

If this ends up being too much of a read for you jog to the “Update 9/17/13” to get the general overview of progress. Like any project on a timeline, not everything works quite as well as they would have liked it to. But it’s the journey that makes something like this so fun — a fully working project would signal an end to the enjoyment, right?

[via Workshop 88]

Polyurethane Protecting PCBs

September 20, 2013 by Brian Benchoff 29 Comments

PCB

What you see above is a home-made PCB. No, this isn’t an example of a terrible toner transfer job, but rather evidence of the ravages of time. This board is seven years old, and the corrosion and broken traces show it. Luckily, [George] already has seven years of environmental data for a cheap DIY soldermask.

Seven years ago, [George] took a piece of copper clad board, masked half of it off, and sprayed it with fast drying polyurethane. After drying, he put it on a shelf in his garage. The results were fairly surprising – the uncovered portion is covered in verdigris, while the coated half is still shiny and new.

[George] took this a bit further and experimented with other spray can coverings. He found Testors spray enable worked just like the polyurethane, burning off when the heat of a soldering iron was applied, and also passed for a professional PCB.

Learn Machining From An Old School Metal Master

September 20, 2013 by Adam Fabio 24 Comments

In the depths of YouTube there are still some jewels to be found. [Keith Fenner] is one of them. [Keith] owns Turn Wright Machine Works in Cape Cod, MA. From his small shop, He works on everything from sailboats to heavy equipment.

[Keith] describes himself as “An artist, and a jobber, 36 years in the trade”. We think he could add teacher to that list, as we’ve learned quite a bit about machining from his Youtube channel.

One of the interesting things about [Keith] is his delivery on camera. He makes the viewer feel like an apprentice machinist working alongside him. Rather than carefully setup shots with graphics, [Keith] narrates as he works paying jobs. He also has no problem showing us his mistakes – and recovery from them, as well as his victories.

The main tools at Turn Wright are the lathe and mill, but [Keith] isn’t old fashioned by any means. He has a complete PlasmaCAM setup and isn’t afraid to do a little computer work.

Most of [Keith’s] projects are broken up into several videos. One of our favorites is “So you broke it off in your hole”. In this series [Keith] shows what it takes to get a broken screw extractor (or EZ Out) out of a large diesel turbo. Get a feeling for what [Keith] has to offer with his “Day in the LIfe” video after the break.

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Heavy Lifting Copters Can Apparently Lift People

September 20, 2013 by Brian Benchoff 32 Comments

Online RC store Hobby King is once again encouraging people to push the limits of what quadcopters and other multirotor remote control vehicles can do. They call it the beerlift and the goal is simple: build a multirotor craft capable of carrying the greatest amount of beer (or water, everything is measured by weight).

The competition is over, but the results were spectacular. The vehicle with the largest lift capacity – pictured above – was built by [Olaf Frommann] and carried 58.7 kilograms, or nearly 128 pounds to a hover a few feet off the ground. Last year the biggest lift was a mere 47 kg with an eight-rotor craft.

It was still an impressive showing all around. The biggest lift in the 700 class – 700 mm from rotor to rotor – was done by [David Ditch] with 19.6 kg. You can check out some of the best entries below, including an amazing aerobatic quadcopter that can successfully loop carrying a cup of beer,

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Getting Your Feedback And A Staff Update

September 20, 2013 by Mike Szczys 40 Comments

Please join me in welcoming four new members to our crew. I published a post calling for applications almost two weeks ago. I wouldn’t say we were overwhelmed with applications. But I would say we were overwhelmed with qualified applicants. Hackaday writers need to be Jacks of all Trades in order to recognize and feature the best hacks from a wide range of disciplines. To this end we chose writers who have interests in areas what will complement those already represented by the team. I couldn’t be happier with the new contributors. Please join me in welcoming [James Hobson], [Todd Harrison], [Phillip Ryals], and [Adam Fabio]. They’ve already been hard at work dishing up fresh hacks, but you can learn more about their backgrounds by reading the biographies on our Staff Page.

You may have noticed a change this week. Although we’re an English language blog based in the United States, our statistics show readers throughout the world (in fact, almost a third of our writing team aren’t Americans). For this reason we changed our post scheduling earlier this week to a 24-hour cycle. This means more time between posts, and of course new posts being published in the middle of the night. Keep reading for a few more tidbits and a chance to give us your feedback.

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Visually Tune Your HF Antenna Using An Oscilloscope And Signal Generator

September 20, 2013 by Todd Harrison 15 Comments

Lots of readers are into toying around with RF and ham radios. One thing that is always of concern is tuning the antenna. New equipment is never cheap, so whenever another option comes along that uses existing test gear it gets our attention. [Alan Wolke] aka [w2aew] covers a process he uses to tune his HF antenna using a signal generator and oscilloscope.

The process is more of a teaching aid than a practical replacement for commercial equipment mostly because proper signal generators and oscilloscopes are large items and sometimes not available or affordable. That said, if you do have such test gear you only need build a simple breakout board containing a form of wheatstone bridge where the unknown Rx is the antenna. Two oscilloscope probes are connected across the bridge balance nodes. Some special care needs to be taken matching probe cable length and 50 ohm input impedance to the oscilloscope. A couple of 1K probe coupling resistors are also needed to prevent affecting the impendence at the hookup points. Once the selected signal is injected you can adjust an antenna tuner until the two voltage waveforms match on the oscilloscope indicating your antenna network is tuned to 50 ohm impedance with no reactance.

Being able to tune your antenna visually can really help you understand what is going on in the turning process; matching not only input impedance but also phase shift indicating inductive or capacitive reactance. Join us after the break to see the video and for information on what’s presented in the second part of [Alan’s] presentation.

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