Turning A Router Into An APRS Gateway

June 9, 2011 by Brian Benchoff 15 Comments

[Chris Kantarjiev] is an amateur radio enthusiast (call sign K6DBG) and does a lot with the APRS. We think his build, turning a WRT54gl router into an APRS gateway will be very useful for the APRS tracker builds we’ve been covering.

Setting up an Internet Gateway, or igate, on APRS usually requires a ‘real’ computer. [Chris] didn’t like that idea, so he took aprs4r, igate software for embedded devices, and pruned it down to fit on the 4MB of flash and 16MB of RAM in the WRT.

The actual APRS hardware is connected though headers soldered onto the WRT54gl’s board which go to a small PIC-Based TNC. [Chris] argues that the APRS ‘backbone’ is great, but there aren’t enough nodes on the network for full coverage. We thing this would be a great way to put cheap hardware out in the wild to cover those gaps in the APRS network.

Check out the video for a rundown of the modded WRT54g after the break. If you’re interested amateur radio, Field Day is coming up in just 2 weeks. Find a local club and check out what’s possible with amateur radio.

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Machine Precisely, Methodically Arranges Water Droplets

June 8, 2011 by Mike Nathan 31 Comments

While some projects we feature are meant to perform a useful function or make life easier, others such as this art installation by [Pe Lang] are far less functional, but amazing nonetheless.

Taking a cue from CNC-style machines, his creation is an experiment in falling objects and the properties of water. The machine methodically moves along a small 370 x 330 mm plate that is constructed out of a special omniphobic material. A syringe full of water travels along with the machine’s arm, depositing a single 3.3 mm wide drop of water on the board every few seconds as it moves along. Due to the surface tension of the water, each droplet forms a near perfect sphere on the plate without disturbing any of its neighbors.

Once the machine is finished, it leaves the matrix of water droplets to evaporate, after which the machine starts its careful process once again. It really is amazing, regardless of the fact that it doesn’t exactly “do anything”.

Be sure to check out the video below to see the exhibit in action.

[via Make]

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Cleaning Flux From PCBs The Easy Way

June 7, 2011 by Mike Nathan 77 Comments

While we’re all for building circuits on protoboard or constructing a deadbug circuit for a last minute project, it’s always nice to see a proper PCB now and again. We think that leftover flux can sometimes make even the nicest of circuit boards look a bit dingy, and Hackaday reader [RandomTask] wholeheartedly agrees. He wrote in to share a method he found online that he uses to get his PCBs squeaky clean after soldering.

The secret to his clean PCBs is a product called Poly Clens. It’s essentially a paint brush cleaner that does a great job at removing flux without having to resort to using a brush to scrub it off the board. [RandomTask] simply submerges his newly assembled board in a small container filled with Poly Clens, agitating it for about half a minute or so. After the flux has been removed he rinses it with water, pats it dry, then ensures the board is moisture-free with a few passes of his heat gun.

He says that the entire process takes him less than 5 minutes per board, which is far better than the old alcohol and stiff brush method he used in the past.

What tips or tricks do you have for getting your new projects cleaned up? Be sure to share them with us in the comments.

Mini-cannon Built From A BBQ Lighter Fires Airsoft Pellets

June 6, 2011 by Mike Szczys 24 Comments

[Nighthawkinlight] has made his own palm cannon to shoot Airsoft pellets. His process, which he guides us through step-by-step in the video after the break, definitely invokes MacGyver buy using commonly available parts in a way they were not intended.

He starts with a barbecue lighter, removing the screws and plastic housing to get at the clear plastic butane reservoir which serves as the body of the cannon. The butane is carefully released from the tank, and the output valve is modified to receive the barrel. In this case the barrel from an old Airsoft gun was used, but a metal pen housing could do the trick as well. The spark igniter from the lighter is also reused, but two bolts have been screwed into the reservoir and are used as probes for the igniter wires. In order to fire this one-shot-wonder, a cotton swab soaked in 90% alcohol is inserted through the bolt on the left side. After inserting an Airsoft pellet the trigger is pulled to ignite the vapors.

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Beginner Concepts: Designing Transistor Control Circuits

June 6, 2011 by Mike Szczys 18 Comments

Need to switch something on or off using a microcontroller? Using a transistor is one of the best ways to do this, but how exactly do you design properly for transistor switching? [Ben Krasnow] put together a tutorial in which he does an excellent job of explaining the ins and outs of designing transistor control circuits.

We’ve embedded his twenty-minute video after the break. In it he talks about the use of transistors, the difference between NPN and PNP transistors, and the design specifics you need to know when working with them. We think that beginners will find [Ben’s] demonstration of how to calculates Hfe, which is the base current necessary to fully switch the transistor. If this is gibberish to you, have no fear. [Ben’s] instruction is clear and easily understandable.

The one thing we missed in the video is clarification about base current protection for PNP transistors. [Ben] mentions that there’s no easy circuitry that can be used on the base of a PNP to regulate flow from the emitter to the base, but he doesn’t elaborate. Otherwise, it’s everything we could have wanted on the topic.

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A Big Transformer, Because It’s Cool!

June 5, 2011 by Nick Schulze 29 Comments

[Grenadier] Had some spare wire, electrical tape, and a giant ferrite core laying about and decided to create a massive and pretty snappy looking disk shaped flyback transformer. Dubbed the Fryback, he claims that it will “revitalise your health and bring wondrous wealth and prosperity to your family”.

He chose a disk shaped transformer because they look cooler, fair enough.. (oh and they reduced inter-winding capacitance and the voltage difference between layers). The construction is fairly simple, but time consuming. Grenadier goes through the important steps on his website, but be prepared for 25 hours of winding wire if you decide to make your own.

Running at 48V the Fryback can output 8kV at a very high current, producing some nice thick 30cm long sparks. Check out the video after the break to see the Fryback in action.

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OnshouldersTV Knows How To Use OpenSCAD

June 3, 2011 by Gerrit Coetzee 7 Comments

Recently there’s been a increase in the popularity of OpenSCAD as the tool of choice in the 3d printing community. [Gavilan Steinman] is putting out a series of webTV shorts on the use of OpenSCAD. While it lacks a lot of the features of big CAD suits (such as the ability to generate drawings of your parts), the community has proven it’s effectiveness as a design tool. There are only two episodes out so far but they cover OpenSCAD, mathcast, 3d printing, and a really neat robot design. Watch them below.

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