Tiny R/C P-51D Mustang Tips The Scales At 3 Grams

November 11, 2014 by Adam Fabio 18 Comments

Commercial R/C aircraft have been getting smaller and smaller with each passing year. In the early 2000’s, a palm-sized plane or helicopter was the dream of many an R/C enthusiast. Today, you can pick them up for around $20 USD at the local mall. The smallest models however, are still built by an elite group of modelers. Weighing in at a mere 3 grams, [Martin Newell’s] P-51D mustang model certainly puts him into that group. While the P-51’s 11.6 cm wingspan may not make it the smallest plane in the world, its many functions make it incredible.

The Mustang is an 8 channel affair, with elevator, throttle, rudder, ailerons, flaps, navigation lights, working retracts, and flashing cannon lights. That’s Wright, we did say retracts, as in retractable landing gear on a 3 gram model.

All the Mustang’s flight surfaces feature fully proportional control. However, there are no closed loop servos involved. The flight surfaces use magnetic actuators, consisting of a tiny neodymium magnet surrounded by a coil of magnet wire. We’re not sure if the signals to these actuators is straight PWM or if [Martin] is varying the frequency, but the system works. The retracts use heat-sensitive Nitinol “muscle wire” along with a bellcrank system to make sure the landing gear is up and locked after takeoff, and comes down again before a landing.

We don’t have any in-flight video of the Mustang, but we do have footage of an even smaller 1.2 gram plane [Martin] has been flying lately. Click past the break to check it out!

Continue reading “Tiny R/C P-51D Mustang Tips The Scales At 3 Grams” →

Forkless Motorcycle Tears Up The Track

November 10, 2014 by Adam Fabio 19 Comments

The bike above may look like a pristine Yamaha prototype, but it’s actually the work of [Julian Farnam], a motorcycle hacker of the highest level. We caught his Yamaha A-N-D FFE 350 on OddBike, and you can read [Julian’s] own description of the bike on his Slideshare link.

The FFE 350 started life as a Yamaha 1990’s RZ350 two-stroke racer. From there, [Julian] gave it his own Forkless Front End (FFE) treatment. Gone is the front fork, which while common in motorcycle and bicycle design, has some problems. Fore-aft flex is one – two thin tubes will never make for a rigid front end. Changing geometry is another issue. Since forks are angled forward, the front wheel moves up and to the rear as the shocks compress. This changes the motorcycle’s trail, as well.

Forkless designs may not have these issues, but they bring in a set of their own. A forkless design must have linkages and bellcranks which are often the source of slop and vibration. [Julian’s] design uses two sets of linkages in tension. The tension between the two linkages removes most of the slop and provides that directly connected feel riders associate with forks.

The FFE 350 wasn’t just a garage queen either – it laid down some serious laps at local tracks in Southern California. Unfortunately, the forkless design was too radical to catch on as a commercial venture, and the FFE has spent the last few years in storage. [Julian] is hard at work bringing it back to its 1998 glory, as can be seen on his restoration thread over on the Custom Fighters forum.

Wax Motors Add Motion To Your Projects

November 10, 2014 by Adam Fabio 19 Comments

[electronicsNmore] has uploaded a great teardown and tutorial video (YouTube link) about wax motors. Electric wax motors aren’t common in hobby electronics, but they are common in the appliance industry, which means the motors can be often be obtained cheaply or for free from discarded appliances. Non-electric wax motors have been used as automotive coolant thermostats for years. Who knows, this may be just what the doctor ordered for your next project.

As [electronicsNmore] explains, wax motors are rather simple devices. A small block of wax is sealed in a metal container with a movable piston. When heated, the wax expands and pushes the piston out. Once the wax cools, a spring helps to pull the piston back in.

The real trick is creating a motor which will heat up without cooking itself. This is done with a Positive Temperature Coefficient (PTC) thermistor. As the name implies, a PTC thermistor’s resistance increases as it heats up. This is the exact opposite of the Negative Temperature Coefficient (NTC) thermistors we often use as temperature sensors. PTC’s are often found in places like power supplies to limit in rush current, or small heating systems, as we have in our wax motor.

As the PTC heats up, its resistance increases until it stops heating. At the same time, the wax is being warmed, which drives out the piston. As you might expect, wax motors aren’t exactly efficient devices. The motor in [electronicsNmore’s] video runs on 120 volts AC. They do have some advantages over solenoid, though. Wax motors provide smooth, slow operation. Since they are resistive devices, they also don’t require flyback diodes, or create the RF noise that a solenoid would.

Continue reading “Wax Motors Add Motion To Your Projects” →

RFToy Makes Wireless Projects Easier

November 10, 2014 by Adam Fabio 7 Comments

[Ray] has created RFToy, a simple gadget to aid in setting up wireless systems with a variety of common radio modules. RFToy is an open source microcontroller board running on an ATmega328. While RFToy is Arduino code compatible, [Ray] chose to ditch the familiar Arduino shield layout for one that makes it easier to install RF modules, and is more handheld friendly.

[RFToy] includes headers for the popular nRF24L01 2.4 GHz transceiver, as well as 433/315 transmitters and receivers found in many low-cost wireless electronic devices. The 128×64 pixel OLED screen and 3 button interface make it easy to set up simple user interfaces for testing new designs.

[Ray] hasn’t broken any new ground here. What he has done is create a simple tool for wireless projects. Anyone who’s worked on a wireless system can tell you that tools like this are invaluable for debugging why your circuit isn’t talking. Is it the transmitter? The receiver? Something else in the power supply circuit?

Check out [Ray’s] demo video after the break. In it, he sniffs, records, and plays back signals from several remote-controlled outlets. [Ray] also has a great demo of sending temperature data back and forth using an nRF24L01.

Continue reading “RFToy Makes Wireless Projects Easier” →

Deck The Halls With A Raspberry Pi Controlled Christmas Tree

November 9, 2014 by Adam Fabio 3 Comments

You know the holiday season is getting close when the Christmas light projects start rolling in! [Osprey22] is getting a jump on his holiday decorations with his Christmas Tree light show controlled by a Raspberry Pi. Yes, we know he could have done it with an Arduino, or a 555, but the Raspi makes for a convenient platform. With a WiFi module, code changes can be made remotely. The Raspberry Pi’s built-in audio interface also makes it easy to sync music to flashing lights, though we’d probably drop in a higher quality USB audio interface.

[Osprey22’s] Raspberry Pi is running his own custom python sequencer software. It takes an mp3 file and a sequence file as inputs, then runs the entire show. When the music isn’t playing, the Pi loops through a set of pre-defined scenes, changing once per minute.

The hardware itself is pretty straightforward. The Raspberry Pi controls 8 solid state relays through its GPIO interface. 8 strings of lights are more than enough for the average tree. [Osprey22] topped the tree off with a star made of wood and illuminated by a string of 25 WS2801 RGB LED pixels.

Click past the break to see [Osprey22’s] tree in action!

Continue reading “Deck The Halls With A Raspberry Pi Controlled Christmas Tree” →

Dog Tracker Knows Where The Dirt Is

November 8, 2014 by Adam Fabio 24 Comments

[Eric] is well on his way to making one of the less pleasant chores of pet ownership a bit easier with his dog tracking system. The dog tracker is actually a small part of [Eric’s] much larger OpenHAB system, which we featured back in July.

As a dog owner, [Eric] hates searching the yard for his pet’s droppings. He had been planning a system to make this easier, and a local hackerspace event provided just the opportunity to flesh his ideas out. The Dog Tracker’s primary sensor is a GPS. Most dogs remain motionless for a few seconds while they go about their business. [Eric’s] Arduino-frgbased system uses this fact, coupled with a tilt sensor to determine if the family pet has left any presents.

The tracker relays this information to the home base station using a HopeRF RFM69 transceiver. The RFM69 only has about a 900 foot range, so folks with larger properties will probably want to spring for a cellular network based tracking system. Once the droppings have been tracked, OpenHAB has an interface

[Eric] has also covered runaway dogs in his design. If Fido passes a geo-fence, OpenHAB will raise the alarm. A handheld dog tracker with its own RFM69 can be used to chase down dogs on the run. Future plans are to miniaturize the dog tracker such that it will be more comfortable for a dog to wear.

Continue reading “Dog Tracker Knows Where The Dirt Is” →

3D Printed Drone Follows The Leader

November 6, 2014 by Adam Fabio 15 Comments

[peabody124, aka James] has been active in the drone world for several years now, first with OpenPilot, then TauLabs, and now with his own Spark and Sparky2 boards. [James]’ latest creation is a 3D printed quadcopter using both his Sparky2 board and his Sparky2BGC Brushless Gimbal Controller.

[James] had always wanted a quad which would follow him and his friends while they were having fun, sort of like his own flying camera platform. His current setup is finally approaching that goal. [James] designed his new quadcopter to use his Sparky2 flight controller and the KISS 18 amp Electronic Speed Controller (ESC). He also incorporated a brushless gimbal to keep his Mobius action cam pointed at a whatever the drone may be tracking.

To keep the internal layout clean, [James] designed a power distribution board which solders right up to the ESCs. The internal layout is seriously clean, with flat panels which keep the electronics safe during crashes.

The crash protection turned out to come in handy, as [James] managed to hit a couple of drone-eating trees during testing. Thankfully, having a 3D printed quad means spare parts are just a few hours of printing away. Check out the video below for footage of [James]’ test flights, and of the quad tracking his cell phone via an RF link.

Continue reading “3D Printed Drone Follows The Leader” →