Hackaday Links: July 13, 2012

Testing LEDs

Over at the Albuquerque, NM hackerspace Quelab, [Alfred] needed to test a bunch of surface mount LEDs. He ended up building a pair of 3D printed tweezers with a pair of needles attached to the end and a space for a coin cell battery. It works and Quelab got a new tool.

Woo Raspberry Pi

[tech2077] added an FTDI chip to his Raspberry Pi to do a little single cable development. We’ve seen a few similar builds, but surprisingly nothing related to the on board display serial interface. This wiki page suggests it’s possible to connect an iPhone 3G or iPhone 4 display directly to the Raspi. Does anyone want to try that out?  Nevermind, but it would be cool to get a picture from a display plugged into that display port on the Raspi.

I like to ride my bicycle, I like to ride my bike

Over at the 23b hackerspace a few people were having trouble finding a good bike cargo rack that wasn’t overpriced. They built their own with $30 in materials and a salvaged milk crate. It looks great and is most likely a lot more durable than the Walmart model.

If that cargo rack fell off, it would look like this

Apparently you can get ‘spark cartridges’ to attach to the underside of a skateboard. [Jim] saw these would look really cool attached to his bike so he did the next best thing. He attached them to his sandals. It does look cool…

Less heat, less noise

[YO2LDK] picked up a TV tuner dongle for software radio and found it overheated and stopped working after about 15 minutes (Romanian, Google Translate). He hacked up a heat sink from an old video card to solve this problem. Bonus: the noise was reduced by a few tenths of a dB.

Electric bike (earplugs not included)

It’s obvious this bike has some extra parts. But look closely and you’ll see the chainring has no chain connecting to it. Pedaling will get you nowhere since [PJ Allen] rerouted the chain in order to drive this bicycle using an electric motor.

He’s got beefy motor which pulls 350 Watts at 24 Volts. For speed control he opted to use an Arduino, pumping out PWM signals to some MOSFETs. This results in an incredibly noisy setup, as you can hear in the bench test video after the break. But once this is installed on the bike it doesn’t quiet down at all. You can hear the thing a block away.

The original road test fried the first set of 7A MOSFETs when trying to start the motor from a standstill. It sounds like the 40A replacements he chose did the trick through. We didn’t see any information on the battery life, but if he runs out of juice on the other side of town we bet he’ll be wishing he had left the chain connected to the crankset.

[Read more...]

Revolight clone

[Fabian.E] wanted to light up the rims on his bike, but didn’t want to shell out a bunch of clams to get it done. He came up with this system which uses magnets and reed switches to light up one arc or each bicycle wheel.

He calls it the lightrider and it’s based on the revolights concept. That design uses a microcontroller which is capable of animating patterns when the wheels aren’t spinning. [Fabian's] version can’t do that, but the effect while moving is basically the same. The ring of LEDs around the rim is connected to a battery via a set of reed switches. When these switches move past a magnet on the fork it completes the circuit and switches on that segment of LEDs. The clip after the break gives a demonstration of the finished product, and includes a fast-motion video of the fabrication process.

[Read more...]

Electronic bike derailleur

[Nabil] sent in an awesome electronic bicycle derailleur. Now, instead of pulling a steel cable with a shifting mechanism, [Nabil] can change gears electronically. As a bonus, the derailleur can be controlled by a small bicycle computer, so he’s always in the right gear.

The new electronic derailleur is controlled by a pair of servos with push buttons in the handle bar. This allows [Nabil] to automatically trim his chain, completely eliminating chain rub.

This electronic shifter is part of [Nabil]‘s much large bike computer project. In addition to electronic control of what gear the bike is in, [Nabil] will be adding a GPS, accelerometer, an altimeter and a heart rate monitor and pulse ox meter. That’s an impressive bit of kit, and we cant wait to see the entire project finished. You can pick up the current version of the design over on GitHub and follow all the updates on [Nabil]‘s blog.

Bike alert tells drivers to back off

Bicycle commuters are often in a battle with drivers for space on the road. [Hammock Boy] does all of his commuting on two human-powered wheels, and is quite interested in not getting hit by a car. He decided to ply his hobby skills to build a device that helps keep him safe. It’s not just a tail light, it’s a sensor that shines brighter the closer a car is to the back of the bike.

The sensor portion is the ultrasonic range finder seen in the center of the protoboard. Surrounding it is a set of LEDs. Each is individually addressable with the whole package controlled by an Arduino. The sketch measures the distance between the back of the bike and whatever’s behind it. If there’s nothing, one Red led is illuminated. If there is an object, the lights shine brighter, and in different patterns as the distance decreases.

Certainly the next iteration could use a standalone chip without the need for the whole Arduino. This could even work with two battery cells and no voltage regulator. We also think the use of any other color than Red LEDs is suspect but we do love the concept.

LED bicycle hack makes sure you’re seen at night

The bicycle tail and head lights that we’re accustomed to are small add-on modules. This take on the idea uses strips of LEDs to protect you from behind. They’re very bright, matching the pair of LED headlights that are attache to the handlebars.

Apparently [A.Davis12] had some LED strips laying around. There’s not what we’re used to seeing, but they have a similar footprint so you should be able to substitute the kind that come on a spool and may be cut to length. The majority of the build time was spent integrating the lights and their control wires with the frame of the bike. The frame already has holes in it for feeding the control wires for brakes and gear shifting inside the tubing. It sounds like it was a pain, but eventually he managed to get all of the routing done. Two red strips are zip-tied to the back of the seat stays. They are powered by a lithium battery inside the project box which mounts under the back of the saddle. A flip switch on the case lets you turn them on without stopping.

[Thanks Arpad]

Arduino tells you how rough your last mountain bike ride was

If you want to see what kind of abuse you’re causing your body when out on those single-track rides this system is just the thing. It’s an Arduino data logger that [Wdm006] takes along on the rides with him. When he gets back home, a Python scripts captures the data dump and graphs it. It may sound like a neat trick, but he’s got something planned for that information.

The enclosure mounts to the stem of his bike. It houses an Arduino board with a data logging shield of his own design. That shield holds an SD card for storage, and breaks the other pins out as screw terminals. Right now there’s an accelerometer on the front fork, and some method of recording wheel speed. This is the research phase of an anti-lock brake system (ABS) he plans to build for mountain biking. No word on what hardware he’ll use for that, but we can’t wait to see how it comes out.