Cheap DIY Tilt Switches Are Great In A Pinch

December 2, 2011 by 46 Comments

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[fjordcarver] was looking for some mercury-free tilt switches that wouldn’t break the bank and that were easy to build. He also wanted something cheap, so instead of buying some tilt switches he devised his own that fit all of the criteria he set out. Now, these switches are not your typical fare, and they’re not small either. They are however, cheap, effective, and easy to manipulate/repair.

He picked up a package of metallic craft beads at the store and emptied out two bottles, saving one set of beads that happened to be conductive, i.e. not coated with paint or coloring. The beads were split between two jars, which were then sealed with corks that had a pair of straightened paperclips inserted through them. The bottles were oriented facing away from one another, then attached together with a piece of house wire. One of the leads from each jar was attached to this common wire, while the others were extended with hook up wire for use in the circuit he was building. Pictures definitely explain the mechanism far better than words can, so be sure to check out his tutorial to get a better look at them.

While they might look a bit rough, he says they work great, so give them a try if you have the need.

Children’s Light Up Toy Is An Easy Hand-made Gift

December 2, 2011 by 31 Comments

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While this year’s Christmas lists are dominated by electronic gadgets and other mass-produced toys, it wasn’t always like that. We’re not trying to sound like the old man yelling at the neighborhood kids to get off his lawn, but many of today’s gifts lack the personal touch found in old, hand-made toys.

[henlij’s] son is a budding electronics geek who loves playing with switches and lights, so he was inspired to build him a fun toy to pass the time. He constructed a simple box full of lights and switches that his son could toggle on and off to his heart’s content.

While there’s not a ton going on inside the box, we think that the idea is fantastic. With just a few dollars worth of simple components, anyone who knows their way around a soldering station can build something that will keep a child fascinated for hours.

There’s no reason to stop at buttons and lights either. If we were to build one, we would swap the bulbs out for LEDs, then add a wide variety of switches and dials along with speakers and any other components we could get our hands on.

The options are pretty limitless, so if you happen to know a child that gets a kick out of playing with buttons and switches, why not make him or her something special this year, much like [henlij] did for his son?

Trying To Measure The Speed Of Light With An Arduino

December 1, 2011 by 63 Comments

We know that measuring the speed of light with an Arduino is possible. It’s just that the implementation is hard.

Last month we saw [Udo]’s blinkenlight shield that can be used as a line scan camera. It’s a neat piece of kit, but [Udo] really wants to submit something for the Buildlounge laser cutter giveaway, so he figured measuring the speed of light would be an easy project. If a kid and a chocolate bar can do it, surely it can’t be too hard.

[Udo] hit upon the idea of pulsing a laser pointer and measuring the time of the reflection. Because his blinkenlight shield can be used as a light sensor, all that’s needed is a mirror and a pretty long line of sight. There’s a few problems with the setup though: with the Arduino running at 16 MHz, a photon will travel 19 meters in one clock cycle.

Even with some very clever coding, we’re not really sure detecting an emitted photon is possible at such (relatively) slow clock speeds. We’re thinking [Udo] could source a few hundred meters of optic fiber so the entire experiment could fit on a desk, but feel free to drop a note in the comments if you’ve got a better idea. [Udo]’s demo of his blinkenlight/laser mashup is after the break.

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diy-laser-scanner

Cheap DIY Laser Scanner Is Quite Impressive

December 1, 2011 by 28 Comments

With the introduction of the Kinect, obtaining a 3D representation of a room or object became a much easier task than it had been in the past. If you lack the necessary cash for one however, you have to get creative. Both the techniques and technologies behind 3D scanning are somewhat complicated, though certainly still within reach as maker [Shikai Chen] shows us. (Google Translation)

He wanted to create 3D scanned images, but he didn’t have the resources to purchase a Kinect. Instead, he built his own scanner for about 1/6th the cost. Interestingly enough, the scanner resembles what you might imagine a very early Kinect prototype looked like, though it functions just a little bit differently than Microsoft’s creation. The scanner lacks any sort of IR emitter/camera combo, opting to use a laser and a USB VGA camera instead. While scanning, the laser shines across the target surface, and the reflected light is then picked up by the camera.

So how does this $25 DIY laser scanner measure up? Great, to be honest. Check out the video below to see how well his scanner works, and be sure to take a look through his second writeup (Google Translation) as well for more details on the project.

[via Seeedstudio]

[youtube=http://www.youtube.com/watch?v=jLZ-s9KRzG8&feature=player_embedded&w=470]

Multivibrator In Theory And Practice

December 1, 2011 by 60 Comments

We must admit that we’ve been guilty of using a microcontroller to make two LEDs blink alternately in the past. It’s not the worst transgression, but it stems from our discomfort with analog circuits. Luckily, [Ray] published an illustrated guide on building multivibrator circuits. This is a simple method of assembling a two-output oscillator. All it takes is a pair of NPN transistors, which are then switched by on and off based on a resistor-capacitor (RC) timer.

[Ray] does a good job of walking us through how the circuit works at each stage of one complete cycle. You’ll need to read carefully, but the supplementary schematics he uses to water down snap shots of the various electrical states really helped us understand.

Of course, blinking LEDs isn’t the sole purpose of a multivibrator. It is a method of producing a clean square wave which can be used as a clock signal for TTL logic chips. Oh, who are we kidding, see the blinky goodness for yourself in the video after the break.

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Milling Interlocking Wooden Rings

December 1, 2011 by 22 Comments

[Johan von Konow] wanted to make something special as a wedding gift to his wife. He decided a pair of interlocking miniature rings would be the perfect keepsake. He started his search for a way to mill the wooden rings from a solid piece of wood, and documented his journey for our enjoyment.

This project poses an interesting challenge. Most CNC mills offer three axes of freedom, but he only had a 2D mill meant for routing PCBs. This means the cuts can only be made from the top down at one depth. In order to fabricate the rings he needed to cut from more than one side. With more study, [Johan] discovered that it would be necessary to cut the wood stock from eight different angles before the rings would be complete.

The solution to the problem was to first mill a jig to hold the wood stock. It has positions to hold the stock at each different angle. The final step before starting the cut was to mill the stock itself to perfectly fit his custom jig. We think it turned out great, thanks in part to hand filing, sanding, and polishing to smooth the marks left from milling.

Make Your Own Spray Paint Cans

December 1, 2011 by 48 Comments

[Mikeasaurus] found a way to build his own refillable spraypaint canister. The donor vessel used here is a plastic soda bottle. It’s a great choice since it is engineered to house a pressurized liquid and you can find them for free by intercepting a satisfied soda consumer before they reach the recycling bin.

He repurposed the spray nozzle from a commercial spray paint can. By first releasing all of the pressure from the empty paint he could then use a hack saw to remove the top disk. He used Sugru to attach it to the bottle cap which has a hole drilled in the center to accept the feed straw. We wonder if there wouldn’t be a better way to attach this from the inside of the cap for better resistance to bottle pressure?

The final piece of hardware is a Shrader valve from a bicycle inner tube. This lets you pump up the pressure in the bottle. You’ll need to dilute the paint you use to make it sprayer-friendly. [Mikeasaurus] diluted his six to one which might have been a bit too much judging from the drips seen in the video after the break.

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