Most new hams quickly learn that the high-frequency bands are where the action is, and getting on the air somewhere between 40- and 160-meters is the way to make those coveted globe-hopping contacts. Trouble is, the easiest antennas to build — horizontal center-fed dipoles — start to claim a lot of real estate at these wavelengths.
So hacker of note and dedicated amateur radio operator [Jeri Ellsworth (AI6TK)] has started a video series devoted to building a magnetic loop antenna for the 160- and 80-meter bands. The first video, included after the break, is an overview of the rationale behind a magnetic loop. It’s not just the length of the dipole that makes them difficult to deploy for these bands; as [Jeri] explains, propagation has a lot to do with dipole height too. [Jeri] covers most of the mechanical aspects of the antenna in the first installment; consuming a 50-foot coil of 3/4″ copper tubing means it won’t be a cheap build, but we’re really looking forward to seeing how it turns out.
We were sorry to hear that castAR, the augmented reality company that [Jeri] co-founded, shut its doors back in June. But if that means we get more great projects like this and guided tours of cool museums to boot, maybe [Jeri]’s loss is our gain?
Continue reading “[Jeri] Builds a Magnetic Loop Antenna”
If your problem is how to put out a maximum amount of repetitive graffiti with a minimum amount of effort, we’ve got your solution. Or rather, [Ariel Schlesinger] and [Aram Bartholl] had your solution way back in 2010. The banner image says it all.
Of course, it doesn’t have to be graffiti that you’re spraying. This idea could be easily adapted to stencil that repeating floral pattern that my grandmother had on her walls too. It’s like a patterned paint roller, but for a spray can.
There’s room for improvements here. For instance, we can’t cut out stencils to save our life but we know where to find a laser cutter. From the look of things, they could use a slightly bigger stencil and something to catch the drips. There’s probably an optimal size for this gizmo, which calls for experimentation.
We’re somewhat obsessed with graffiti machines. Whether it’s a graffiti quadcopter or the elegant and non-permanent sidewalk-chalker style bots, we like machines that make “art”. What’s your favorite graffiti hack?
Thanks [n0p;n0p;n0p;] for the (archival) tip!
[Oscar] wonders why hobby projects ignore all the powerful brushless motors available for far less than the equivalent stepper motors, especially with advanced techniques available to overcome their deficiencies. He decided it must be because there is simply not a good, cheap, open source motor controller out there to drive them precisely. So, he made one.
Stepper motors are good for what they do, open-loop positioning along a grid, but as far as industrial motors go they’re really not the best technology available. Steppers win on the cost curve for being uncomplicated to manufacture and easy to control, but when it comes to higher-end automation it’s servo control all the way. The motors are more powerful and the closed-loop control can be more precise, but they require more control logic. [Oscar]’s board is designed to fill in this gap and take full advantage of this motor control technology.
The board can do some pretty impressive things for something with a price goal under $50 US dollars. It supports two motors at 24 volts with up to 150 amps peak current. It can take an encoder input for full closed loop control. It supports battery regeneration for braking. You can even augment a more modest power supply to allow for the occasional 1 KW peak movement with the addition of a lithium battery. You can see the board showing off some of its features in the video after the break.
Continue reading “Hackaday Prize Entry: Industrial Servo Control On The Cheap”
[Brian McNamara] fed the output of his guitar pedal back into its input creating a looped synthesizer. He started with an effects pedal he made but now we think he’s ended up with an electronic stomp box. Check out the results in the video after the break. Now he needs to make the knobs foot-friendly so he can monkey with this while playing guitar.
Continue reading “Stomp box synthesizer”
This guitar pedal can record, playback, and modify samples. [Colin Merkel], also know for his work on electronic door locks, built this to replicate some guitar effects he heard in recordings. By tapping the button at the bottom with your foot the device begins recording. Another tap stops the recording and starts the loop. That’s where the rest of the controls take over, with settings to adjust the speed of playback, volume, and the type of playback looping. The video after the break gives a great demonstration of these features.
[Colin] built this around a PIC 18F877A with a 256k RAM chip to store the sample. There’s a bunch of other components that go into this and we’re dumbfounded that he built it on protoboard. This would be a multi-breadboard prototype for us and we wouldn’t think twice about laying out and etching our own PCB. He admits that the point-to-point soldering stretched his skills to the limit but he doesn’t say how many hours it took to get the circuit up and running. This is a great addition to the cool guitar pedals we’ve seen here.
Continue reading “Looping foot pedal”
[Michael] tipped us off about an incredible build from back in 2005. The Melloman is a keyboard that uses a different tape loop for each key. The instrument is generally known as a Mellotron, and consists of a different looping tape for each key. When a key is depressed, the head comes into contact with the key and plays the sound sample.
This particular implementation uses 14 Walkmans to supply the tape loops. The Walkman units are constantly playing but the audio output is not enabled until a key is depressed. The main description of the instrument is on the final project page linked above but there are many construction photos available in the build log.
Update: After the break we’ve embedded a video that will take you on a tour of the components of the Melloman. To clear up the looping issue: a Mellotron uses tape loops, but the Melloman uses tapes that are 30 minutes on each side instead of loops.
Continue reading “Melloman tape-looping keyboard”