Make Any Scrap Of Paper Sticky With 2000 Volts

Who needs chemistry when a little bit of physics will do? Instead of brewing up a batch of weak adhesive to make his own post-it notes, [Valentin] built this handheld device to add an electrostatic charge to bits of paper. Just give them a couple of seconds to charge and they’ll stick to the wall with ease.

The charging circuit is pretty simple, involving a transformer, transistor, resistor, and four diodes for rectification. He walks us through the build process, free forming the circuit using the transformer housing as a base. Once the circuit is fully assembled, a 9 volt battery connector is added and the fragile parts are hot-glued in place. It boosts the output voltage all the way up to 2 kV, but it’s still safe because it’s at a very low current.

The concept is akin to the high-voltage bulletin board seen last month. We wonder how long the notes will stay in place without an active electrical connection to keep the charge?

Keeping Christmas Present Hunters Guessing With QR Code Gift Tags

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[Thadd Brooks] is a geeky dad of the highest degree. His kids are constantly trying to figure out what mom and dad bought them for Christmas, while he continues to think up ways to stymie their progress. He certainly could have put a few prank presents under the tree, but he opted to go a different route, confusing his smartphone-wielding kids with QR codes.

Each gift under the tree bears no name tag, rather they are adorned with a single QR code sticker which [Thadd] printed out. When scanned, the code brings his children to a page on his web server stating who the gift is for.

The catch? Well, the codes bring up a random page each time, attributing the gift to every member of the family along the way. There’s no chance that any of the kids will be able to correctly identify their gifts before Christmas Eve, when [Thadd] flips a switch on the server and reveals the actual gift recipients.

It’s certainly a clever, yet frustrating, way to keep his family on their toes, and we think it’s a pretty awesome idea.

If you’d like to see some of the pages he has created to confuse his kids, just click the “Search” button on the link above.

Prank Gift Keeps Curious Hands At Bay

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You all know that person.

The one who picks up every present with their name on it, shaking it before busting into their best Carnac the Magnificent impression. Heck, you might even be that person.

[Jason] was thinking about how to combat the gift shaker in his life and put together a simple prank that’s sure to provide him some enjoyment when the shaking and guessing commences.

He bought a premade audio module that stores about 20 seconds of sound, replacing the pushbutton trigger with a pair of wires that can easily make contact when the box is vigorously moved. Everything was carefully mounted in a gift box before being wrapped and set under the tree to surprise the eager gift shaker.

We definitely like the idea, since there are a plethora of ways to customize/enhance [Jason’s] work to fit your specific needs. Whether you go with the kitten/puppy in a box theme, or wire in an incredibly loud alarm, your resident gift inspector will never look at presents the same way again!

Continue reading to see [Jason] explain his gift prank in more detail.

Continue reading “Prank Gift Keeps Curious Hands At Bay”

Smelting Metal In Your Microwave Oven

Grab some scrap metal and a microwave oven and you’ll be casting your own metal parts in no time. [Mikeasaurus], who is known for doing strange things like making Silly Putty magnetic or building his own spray paint bottles, doesn’t disappoint this time around. He read about microwave smelting in Popular Science and is giving it a shot himself.

The image above shows him pouring an ingot. He build an insulated brick enclosure inside of the microwave oven, then set it to go ten minutes for a 50/50 lead/tin mixture, or fifteen minutes for silver. This will vary based on the power rating of your microwave. You can see in the video after the break that the setup gave him some trouble shortly after pouring. It wasn’t a problem with the molten metal, but spontaneous combustion of the rigid foam insulation that did him in. We shouldn’t say ‘I told you so’, but that insulation says right on it that it’s flammable!

This isn’t the first time we’ve looked at casting metal melted in a microwave. Check out this other version posted back in 2005. Continue reading “Smelting Metal In Your Microwave Oven”

A Wooden Engine Powered By Compressed Air

You may have seen an air powered engine at some point, but most are made out of some sort of metal. This engine, however, is made entirely out of wood (and fasteners). One might wonder how a design like this was conceived, but this may be explained by [Woodgears.ca’s] tagline: “An engineer’s approach to woodworking.”  It should also be noted that this is actually [Matthias’] sequel to  “Wooden Air Engine 1.

The engine itself is a neat device in that it uses power from compressed air (or suction from a vacuum cleaner) to make the piston and connecting rod cycle back and forth to spin a flywheel.  The other connecting rod is used to switch which side of the “clyinder” received air pressure (or vacuum).  A really neat mechanical assembly, and one that took a good amount of skill to make out of wood.  Check out the video after the break to see how it all works!

[youtube http://www.youtube.com/watch?v=ngb4SYR74m4&w=470&h=315%5D

If you’d like your woodworking to be more automatic, check out this post about how to set up a CNC router for your personal use.

Advent Calendar Of Circuits

We missed 60% of it already, but luckily you can easily watch the back catalog of [Alan Yates’] 2011 Advent Calendar of Circuits. As with traditional Advent Calendars he’s got a treat for every day in December leading up to Christmas. Instead of chocolate, the treat is a video about a different electronic circuit.

We didn’t find a playlist link, but you can just head over to his YouTube channel as each day is clearly labelled in the video titles. He starts off with a current limiting voltage regulator. A couple of days later he busts out a metal detector that will be fun to play with. Day 7 brings an AM transmitter/receiver pair, and Day 12 illustrates a burnt-out Christmas light detecting tool which we’ve embedded after the break.

The sheer volume of projects he’s putting out every day is remarkable and delightful. He doesn’t even limit himself to one video a day, but has posted several ‘extra’ editions with quick, circuit demos. Continue reading “Advent Calendar Of Circuits”

Twitter-enabled Candy Machine Dispenses Treats On Command

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[Michael Nilsson] and [Markus Olsson] were contemplating how to motivate members of their dev team when they came up with the idea of a candy machine that automatically dispenses treats when someone has earned it.

They picked up a candy machine, a continuous rotation servo and a controller, then got busy automating the dispenser. The mechanism behind the operation is actually pretty simple as you can see in [Michael’s] writeup. They disassembled the machine, removing the gear from the manual crank, attaching it to the servo. Once the servo was mounted place, they installed the servo controller and connected it up to a spare laptop.

The heavy lifting is done by a Ruby script that uses the Twitter API to scrape any mentions of @_macke_ or @sidpiraya. Incoming messages are checked for the words “give” and “candy”, triggering the machine to fork out some sweets.

If you think that their hard work deserves a bit of recognition, feel free to send them some candy by tweeting “give @_macke_candy” or “give @Sidpiraya candy”. Just remember to be considerate – nobody likes spam, not even candy machines!

If you’re interested in seeing the machine in action, be sure to check out the candy dispenser’s live stream at giveawaycandy.com.