Pulse Jet Tea Kettle

September 21, 2012 by Mike Szczys 24 Comments

[Colin Furze] is just showing off in this picture. His pulse jet tea kettle is built well enough to get by without help from a blow torch, but who can blame his showmanship? In fact, once it’s running there’s no flame to be seen. That’s because the combustion happens at an earlier stage of that pipe, heating a segment that is submerged in water so that you may have your tea in no time.

Once this thing is tuned up it roars like a robotic lion. [Colin] yells his commentary at the camera, but it is picked up as nothing more than a blip of distortion. Pressurized propane and air both feed into the jet. they’re regulated by the two knobs on the base of the unit (that enclosure is actually just a pie tin). There is also a 9V battery-powered igniter built into the base. You can see how the unit was built in the video after the break.

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Coil Gun With Parts Pulled From An Electric Stapler

September 21, 2012 by Mike Szczys 18 Comments

[Lou’s] latest tutorial details the process of turning an electric stapler into a coil gun. The stapler is the expensive part, but the rest is pretty simple. He used PVC pipe and a handful of fittings along with a few supplies you probably have kicking around your shop.

It’s surprising how perfect the Bostitch stapler (from which the parts were pulled) is for this project. The mechanism that drives the staples into your pages uses a solenoid with a rather large coil. To turn it into a coil gun you simply need to replace the core of the solenoid with a metal projectile. In the video after the break [Lou] shows us how to make a barrel onto which the coil can be mounted. From there he uses a wooden spacer to position a hunk of smooth metal from a bolt which serves as the projectile. The stapler’s original drive circuitry and trigger mechanism do the rest.

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How To Repair A Ribbon Cable Connection On Consumer Electronics

September 20, 2012 by Mike Szczys 34 Comments

It’s not uncommon in cheaper devices to find a ribbon cable soldered directly to the circuit board like the one pictured above. Using a connector would have been a much more resilient approach, but adding parts adds cost. If you take a close look you’ll see things aren’t looking so great anymore. [Chaotic and Random] pulled this board out of his VW Camper Van. Rather than buy an expensive replacement part, he shows us how to repair a soldered ribbon wire connection.

This repair is rather invasive and he suggests trying some hot-air rework (possibly using a heat gun) to fix up any misbehaving connections. But if that has failed it’s time for the knife. The first step is to cut the ribbon so that the LCD can be removed from the board. From there he peels the remaining scrap off ribbon of the pads. This makes us cringe as it could lift traces from the PCB, but he was gentle enough to avoid it. Now comes the time to start reassembling. After thoroughly cleaning the pads the ribbon is cut straight and resoldered. The trick is to flow the solder without melting the ribbon. He uses tin foil to cover the tip and cools it on a moist sponge just before reflowing solder.

It sounds like more art than science. But when the only alternative is to spend hundreds on a new part it may be worth a try.

Dropping The Nitrogen Bomb In Science Class

September 20, 2012 by Mike Szczys 40 Comments

We took Geology in college. It was pretty cool learning about the hardness of different minerals. But there were no explosions involved. We’re not entirely sure what this class is, perhaps Chemistry, maybe Physics, but we want in. [Dr. Roy Lowry] wows the class with a bomb made of liquid nitrogen. The demonstration was part of his lecture at Plymouth University.

A small explosion is cool, but [Roy] knows how to add the wow factor. To make the bomb he filled a one liter plastic bottle about 1/3 of the way with liquid nitrogen. After tightly sealing the cap it was dropped in that garbage can which had a pool of warm water in it. Before quickly running away he and his assistant dumped a few garbage bags of ping-pong balls on top of it all. When the plastic bottle bursts under the pressure of the expanding gas it sends the garbage can about six feet into the air and floods the room with bouncing white balls. See the whole presentation for yourself in the clip after the break and don’t forget the sound so you can catch the oohs and aahs at the end.

Looks like a Hackerspace recruitment tool if we’ve ever seen one.

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Key Code Door Lock Won’t Endanger Your Security Deposit

September 20, 2012 by Mike Szczys 13 Comments

College students have returned in droves to dorms and apartments at campuses everywhere. So this is the time of year we usually start seeing some coded entry hacks. [Charmonkey] recently took on the challenge at his new apartment. There were some caveats though. He needed to ensure the Landlord could still enter using a key, and he didn’t want to alter the door or the jamb in any way. What he came up with is a coded entry system that can turn the deadbolt.

In order to mount some hardware on the door he removed the inner part of the dead bolt assembly and used the pair of threaded tubes on the adjoining lock section as anchor points. This holds the Pokemon tin he’s using as a project box securely in place. The rest of the components all mount to it. These include the stepper motor that actuates the deadbolt, a switch for manual operation, an Arduino, and a motor driver board.

He got really creative with the keypad. The wires connecting it travel through the door’s peephole and into the smaller plastic project box that hosts the rest of the hardware.

[via Reddit]

How To Build Your Own Dedicated Pandora Radio

September 20, 2012 by Mike Szczys 18 Comments

This mix of modern and retro acts as a standalone Pandora client. It’s certainly a radio upgrade, falling somewhere in between the passive listening of traditional broadcasts, and the complete control of music players that use playlists.

Inside the wooden case a BeagleBoard does most of the work. It’s running Ubuntu 12.04 on which pianobar, a command line interface package for Pandora is running. Those components alone would make a pretty nice listening experience, but since Pandora rolls different music into the mix it’s nice to be able to see what you’re listening to. The four-line LCD is wide enough to display plenty of information. It’s being controlled by a PIC24 microcontroller which also monitors the controls on the top. As you can see in the video after the break, the user interface offers almost everything you could want. It’s easy to switch stations, and you can still register your preferences on each track being played.

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Token Authentication For Gmail Using A EZ430 Chronos Watch

September 20, 2012 by Mike Szczys 11 Comments

Two-factor authentication allows you to use your chosen password, as well as a one-time password to help keep your services secure. The one-time passwords traditionally come from a dedicated piece of hardware, but there are also solutions for smart phones. [Patrick Schaumont] shows how a TI eZ430 Chronos Watch can be used to generate authentication tokens. After walking through the process he uses it to beef up his gmail login.

This method of token authentication is often called Time-based One Time Passwords (TOTP). It’s part of the Open Authentication (OATH) initiative, which seeks to sort out the password-hell that is modern computing. A portable device generates a password by applying an algorithm and a private encryption key to an accuarte time-stamp. On the server side of things a public key is used to verify the one-time password entered based on the server’s own time-stamp. In this case the portable device is the Chronos watch and the server is Google’s own TOTP service.

You can do this with other simple microcontrollers, we’ve even seen an Arduino implementation. But the wrist-watch form factor seen here is by far the most convenient — as long as you always remember to wear the watch.

[Thanks Oxide]