Laser Spirograph

laser-spirograph

Here’s a weekend junk bin project if we’ve ever seen one. [Pat] used a quartet of computer fans to make his laser Spirograph. Deciding to try this simple build for yourself will run you through a lot of basics when it comes to interfacing hardware with a microcontroller. In this case it’s the Arduino Nano.

The Spirograph works by bouncing a laser off of mirrors which are attached to the PC fans. When the fans spin the slight alignment changes cause the laser dot to bob and weave in visually pleasing ways. You can catch twenty minutes of the light show in the clip after the break.

Three of the fans have mirrors attached, the housing of the fourth is used to host the laser diode and make assembly easier. A TC4469 motor driver is used to connect the fans to the Arduino. The light show can be manually controlled by turning the trio of potentiometers which are read using the Arduino’s ADC.

If you manage your way through this build perhaps you’ll move on to a setup that throws laser light all over the room.

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Quick and easy personal evaporative cooler

This quick and easy evaporative cooler might be just the thing the next time the air conditioning goes on the fritz. [Stephen] saw an eBay listing for a personal air conditioner that used a moist sponge and fan to send some cool relief your way. But he wanted to run his own test to see if it really did anything before laying down the cash.

The idea is to run air past a moisture source. Some of the heat energy in the air is reduced through evaporation resulting in the exhaust air feeling a bit cooler. It’s the same concept used in swamp coolers (an evaporative type of air conditioning). To build his device [Stephen] grabbed a refrigerator deodorizer which uses a hinged plastic cage to hold a packet of baking soda. He attached a small PC fan to the cage, then inserted a damp sponge. This is so easy to put together you could hit the dollar store on your lunch break and have some relief for the second half of the work day.

If you’re looking for a technique that cools just a bit better consider leveraging a beer fridge as a personal cooler.

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Bathroom fan that switches itself on when it gets steamy or smelly

At first we thought that [Brandon Dunson] was writing in to tell us he’s too lazy to fix his bathroom fan. What he really meant is that simply replacing the unit isn’t nearly enough fun. Instead, he developed his own bathroom fan trigger based on stinky or humid air conditions. He didn’t publish a post about the project but we’ve got his entire gallery of build images after the break.

The initial inspiration for the project came from a twitter-connected fart sensing office chair. Hiding behind the character display you can see the MQ-4 methane gas sensor which he picked up for the project. But since there’s also a shower in the bathroom he included a humidity sensor with the project. Both are monitored by an ATmega328 which averages 10 readings from each sensor before comparing the data with a set threshold. If the sensors read above this level a relay turns on the bathroom fan.

Don’t be confused by the small DC fans seen above; [Brandon] is still using a proper exhaust fan. These are just used to help circulate the air around the sensors so that low-hanging smells will still trigger the system. This has got to be the perfect thing for a heavily used restroom.

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This diy fume extractor will be a showpiece for your workbench

We have no idea how well this diy fume extractor works, but it sure does look great! We’ve been thinking that it’s time to stop trying to blow away the solder fumes while working on project and this might be just the kind of motivation we need. The 6″ cube doesn’t get in the way of your work, and since it includes a carbon filter it should keep the smell of burning flux to a minimum.

[Jeff’s] project basically brings together a 120mm PC cooling fan with a power source. The fan mounts inside of a steel enclosure he picked up from Digikey. The face plates that come with it were modified to accept the fan, as well as the grill hardware that goes with it. Before assembling he painted the box with some Rustoleum “Hammered” black spray paint. This gives it a texture that will hide any imperfections in your application.

We’re a bit hazy on how this is being powered. It sounds like he’s plugging the cord into mains but we don’t see any type of regulator to feed what must be a 12V DC fan. There are build instruction available but they didn’t clear up our confusion.

Timer-based cooling helps your network survive the summer

Start your week off with a smile thanks to the video [Sammy] put together. It shows off the cooling rack he made for his network equipment. The project was developed out of necessity as the summer weather was causing his modem and router to heat up and at some point one of them would just shutdown and refuse to work again for hours. We haven’t run into this ourselves but it’s good to know that over-temperature safeguards have been built into the equipment.

His solution was to build a rack that offers fan cooling above and below the two pieces of equipment. As with most of his projects, we think making the video (embedded after the break) was half the fun. In addition to playing around with a turntable for some extra special camera effects he gives us a good view of the overall build. The base includes spacers and velcro strips to hold the equipment in place above a pair of exhaust fans. The standoffs at each corner of the rack suspend a second pair of fans above the equipment. But it wouldn’t look nearly as good without some custom LED effects thrown into the mix.

This is purely timer-drive. It’s a plug-in module that uses mechanical timing to switch mains. But some creative circuitry (or a small microcontroller) could implement temperature-based switching instead.

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Tornado lamp made with lasers

[Styropyro] did a great job of taking common parts and making an interesting item. He calls this his Tornado lamp, and it’s made with stuff you probably have around the house — well you might have to substitute more common glassware for that Erlenmeyer flask.

The bulk of the hack is in the base. You’ll find a laser diode pointed at a small scrap of mirror. That mirror is mounted on the center of a small case fan, giving the tornadic effect when spinning. To make everything fit just right, the laser is pointed horizontally, with the fan/mirror at a 45 degree angle. The beam points up through a hole in the project box and illuminates the liquid in the flask. That liquid is water doped with a substance that fluoresces. In this shot it’s some fluorescein, but we did mention you can do this with stuff from around the house. [Styropyro] demonstrates the use of liqud from some highlighting markers as a substitute.

If you’re decoration a mad scientist’s lab this is a perfect companion for a Jacob’s ladder.

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Rebuilding a fried fan motor

The fan motor on [Pete’s] oscillating tower fan conked out on him. It’s a shame to throw away the whole thing, but it’s near impossible to source parts for a small appliance like this one. So he set out to rebuilt the motor and get the thing working like new.

The motor in question is of the brushless AC variety. [Pete’s] gut told him that the failure was due to bad lubrication of the bearings at the factory. It stopped working because the commutator could no longer rotate freely. A check of the continuity of each of the coils led him to this thermal fuse. When the motor seized the AC current built up a lot of heat. This fuse is made to burn out before a fire can start but now it needs to be replaced. With a new one in place he reassembled the motor, making sure to pack the bearings with some quality lubricant. Now he’s once again ready for a long hot summer.