3D-Printed Case Turns Servo Into Quality Linear Actuator

March 31, 2016 by Dan Maloney 20 Comments

Micro servomotors are a hacker staple. You’ll find maybe four or five in an RC plane, while a hexbot build could soak up a dozen or more of the cheap and readily available devices. Unfortunately, long-throw linear actuators are a little harder to come by, so it’s nice to know you can 3D-print linear gearing for standard micro RC servos and roll your own.

Currently on revision 2, [Roger Rabbit]’s design is not just a quick and dirty solution. He’s really thought through the problems he observed with his first revision, and the result is a robust, powerful linear actuator. The pinion fits a trimmed servo crank arm, the mating rack is stout and stiff, and early backlash problems have been solved. The whole case is easy to assemble, and as the video below shows, the completed actuator can lift 300 grams.

We like [Roger]’s build process, especially the iterative approach to improving the design. We’ll stay tuned to see where it goes next – a continuous rotation servo for extra-long throws? While we wait, you might want to check out [Richard Baguley]’s recent primer on servos if you want a little background on the underlying mechanism.

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Start Your Poultry Brood With This DIY Egg Incubator

March 28, 2016 by Dan Maloney 4 Comments

You’d think that hatching chicks from eggs would be easy – after all, birds do it. But it turns out to be a fussy business for humans, and what momma bird does naturally isn’t necessarily easy for us. If your goal is to raise your own brood of peeps, fear not – this DIY egg incubator makes the process much easier.

While [Chris Raynerd]’s incubator was built for quail eggs, pretty much any domestic fowl – chickens, turkeys, ducks, pheasants – will work. The key is temperature control – momma bird’s rump is a natural heat source, and her downy feathers keep the eggs insulated and toasty. That’s a little hard to replicate in a free-air incubator, so [Chris] started with a polystyrene box for insulation. A halogen lamp on a digital thermostat provides most of the heat and keeps the temperature within a degree or two of 37°C. As a backup, a 12 volt halogen bulb on a dimmer keeps the chamber at a minimum of 36°, just in case the main lamp burns out. A small fan and a pan for humidifying water complete the atmospheric controls, although personally we’d arrange the fan to blow across the water to aid evaporation. And a simple grid lets [Chris] turn the eggs regularly, which is another vital service mom provides to her brood.

Sure, it could be Arduino-fied and servo driven, but why bother? This is a simple yet thoughtful build that should see a clutch through to hatching. We’ve seen a few egg incubators before, but even if you’re not interested in raising fowl, the techniques here could easily apply to incubators for biohacking or yogurt making, too.

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Quick And Easy Pressure Forming Makes Plexiglas Domes

March 22, 2016 by Dan Maloney 29 Comments

Thermoplastics are amazingly versatile materials. Apply some heat, add a little force, and within seconds you’ve got a part. It’s not always quite that simple, but as [maxelrad] discovered, sometimes thermoforming can be as easy as blowing up a balloon.

In need of a cowling for an exterior light fixture on an experimental aircraft, [maxelrad] turned to pressure forming of Plexiglas for the hemispherical shape he needed. His DIY forming rig was a plumbing-aisle special: PVC pipe and caps, some air hose and fittings, and a toilet flange for the pressure chamber. The Plexiglas was softened in a toaster oven, clamped over the business end of the chamber, and a few puffs of air inflated the plastic to form a dome. [maxelrad] points out that a template could be applied over the plastic sheet to create the streamlined teardrop shape he needs, and he notes that the rig would likely work just as well for vacuum forming. Of course, a mold could be substituted for the template to make this a true blow-molding outfit, but that would take away from the simplicity of this solution.

There have been a fair number of thermoforming projects featured on Hackaday before, from this DIY vacuum former to a scratch-built blow molder. And while we really like the simplicity of [maxelrad]’s technique, what we’d really love to see is some details on that airplane build.

Arduino Nano Runs Battery Spot Welder

March 22, 2016 by Dan Maloney 23 Comments

Soldering might look like a tempting and cheap alternative when building or repairing a battery pack, but the heat of the iron could damage the cell, and the resulting connection won’t be as good as a weld. Fortunately, though, a decent spot welder isn’t that tough to build, as [KaeptnBalu] shows us with his Arduino-controlled battery spot welder.

When it comes to delivering the high currents necessary for spot welding, the Arduino Nano is not necessarily the first thing that comes to mind. But the need for a precisely controlled welding pulse makes the microcontroller a natural for this build, as long as the current handling is outsourced. In [KaeptnBalu]’s build, he lets an array of beefy MOSFETs on a separate PCB handle the welding current. The high-current wiring is particularly interesting – heavy gauge stranded wire is split in half, formed into a U, tinned, and each leg gets soldered to the MOSFET board. Welding tips are simply solid copper wire, and the whole thing is powered by a car battery, or maybe two if the job needs extra amps. The video below shows the high-quality welds the rig can produce.

Spot welders are a favorite on Hackaday, and we’ve seen both simple and complicated builds. This build hits the sweet spot of complexity and functionality, and having one on hand would open up a lot of battery-hacking possibilities.

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Correcting Color Blindness With DLP Projectors

March 21, 2016 by Brian Benchoff 51 Comments

About five percent of the population is colorblind to one degree or another, and for them seeing the entire spectrum from Roy to Biv is simply impossible. Their eyes simply don’t have the cones to detect certain colors. The brain is the weirdest machine on the planet, though, and with the right tricks of light, even the colorblind can see more colors than they’re accustomed to. That’s the idea behind [PointyOintment]’s entry for the 2016 Hackaday Prize: color blindness correcting goggles.

Any device that claims to correct color blindness comes with a few caveats and a slightly loose interpretation of what ‘color blindness correcting’ actually is. For the same reason you can’t see deep infrared, someone with color blindness cannot distinguish between two colors; the eye simply doesn’t have the sensors to see a specific color of light. This doesn’t mean the ability to distinguish color in color blind individuals can’t be improved, though. The EnChroma glasses use an optical notch filter to block all colors between blue and green, and between green and red. This works, because the human brain is weird enough and can adapt to nearly anything.

[PointyOintmen] isn’t going with an optical notch filter. He’s using spinning color discs from a DLP projector and 3D ‘shutter’ glasses to present the world in different shades of color many times a second. It’s weird, untested, and will take a few hours to get used to, but it is a very interesting idea. Will it allow color blind people to see more colors? That’s a semantic issue, but if you define ‘seeing color’ as being able to differentiate between two different colors, yes, it will.

Tombstone Brings New Life To Board

March 19, 2016 by Bob Baddeley 24 Comments

Making revisions to existing PCBs with surface mount components often leads to creative solutions, and this insertion of a switch over a tombstoned resistor is no exception. According to [kubatyszko], “this is an FPGA-based Amiga clone. R15 serves as joint-stereo mixing signal between channels to make it easier on headphone users (Amiga has 4 channels, 2 left and 2 right). Removing R15 makes the stereo 100% ‘original’ with fully independent channels. Didn’t want to make it permanent so I decided to put a switch.”

Whether [kubatyszko] intends it or not, this solution is not going to be permanent without some additional work to mechanically secure the switch. We’ve tried this sort of thing before and it sometimes results in the contact area of the resistor being ripped off the substrate and separated from the rest of the resistor, rendering it useless. However, the creative use of the pads to get some additional functionality out of the board deserves some kudos.

We love creative fixes for board problems but it’s been a really long time since we’ve seen several of them collected in one place. We’d love to hear your favorite tricks so let us know in the comments below.

Tiny Tea Timer For Your Perfect Cuppa

March 17, 2016 by Dan Maloney 10 Comments

If you’re serious about your tea, you know that the line between a perfect brew and over-steeped dreck is a fine one. Seconds can make a difference, and for the tinkering tea drinker, this might lead you to build a tiny timer with just the features it needs to achieve tea perfection.

The circuit that tea-loving [acidbourbon] came up with for his timer is simplicity itself. It’s just an ATtiny25, an LED, two pushbutton switches and a piezo buzzer on one side of the PCB, with a coin battery on the flip side. The battery holder is an interesting design – a couple of rows of pin headers and a bit of springy metal. The user interface is as simple as the circuit – the buttons increment the time either one or ten minutes. The timer starts right away, the LED heartbeat counts down the seconds, and a distinctly British tune announces when it’s time for tea.

One possible improvement might be to have the LED flash the number of minutes remaining rather than just a single pulse heartbeat. That would be good feedback that you entered the right time in the first place. Other than that, it’s small enough to be handy, does just one job, and does it well – sounds like good design to us. Of course, if you want to complicate it a bit, you could always automate the tea steeping process.

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