GSM-to-Skype Bridge Lets You Lose Those Roaming Fees

May 11, 2011 by Mike Szczys 21 Comments

Here’s the scenario: you’re going to be traveling somewhere and you’ll be charged roaming fees if you use your cellphone. But there is free WiFi available in this place. You can save yourself money by leaving your SIM card at home and using a GSM-to-Skype bridge to take calls on your phone via WiFi.

[Trax] is using a USB GSM modem to take cellphone calls on a PC. He leaves his sim card in this modem so that it can make and receive calls and text messages through your normal telephone number. For some reason, the USB connection only provides control of this modem and doesn’t pass bi-directional audio. To make this happen, he built an audio interface cable using two transformers and a few passive components to connect the modem to the computer’s audio card.

On the software side of things, an application written in Delphi 7 manages the modem, the audio stream, and the Skype application. When a call is incoming it sets up a Skype connection with your handset via the Internet, passing along the caller ID data in the process. If you choose to answer the Skype session the application will pick up the GSM call and you’ll be connected. It works the same way when placing an outgoing call.

This seems easier to manage than a rig that physically pushes a cellphone’s buttons via the Internet.

[Thanks Mure]

Touch-based Synthesizer Is A Wiring Nightmare

May 11, 2011 by Mike Szczys 10 Comments

[Jane] wrote in to let us know about the touch-based synthesizer she and her classmates just built. They call it the ToneMatrix Touch, as it was inspired by a flash application called ToneMatrix. We’re familiar with that application as it’s been the inspiration for other physical builds as well.

A resistive touch screen in the surface glass of the device provides the ability to interact by tapping the cells you wish to turn on or off. Below the glass is a grid of LEDs which represent sound bits in the looping synthesizer track. Fifteen shift registers drive the LED matrix, with the entire system controlled by an ATmega644 microcontroller. Although the control scheme is very straight forward, the jumper wires used to connect the matrix to the shift registers make for a ratsnest of wireporn that has been hidden away inside the case. Check out the demonstration video after the break to see what this looks like and sounds like when in use.

Continue reading “Touch-based Synthesizer Is A Wiring Nightmare” →

Adding Power Trim To A Boat

May 11, 2011 by Mike Szczys 16 Comments

[Matt’s] boat had a trim plate that could be adjusted by hand. The problem with this setup is that the trim angle of a boat changes as you speed up or slow down. Last year he never really went over 35 MPH because of this issue, but he set out to correct that by adding power trim plates for the upcoming boating season.

The original trim plate didn’t have a hinge on it, but simply flexed when tension was added to the adjustment hardware. [Matt] removed the plate and cut it into three parts; one long thin strip to serve as a mounting bracket, and two plates to independently adjust trim for the left and right side of the keel. Some aluminum strip hinges connect the three pieces, and a pair of used actuators acquired from eBay automate the trim adjustment. Each plate is strengthened by a pair of angle brackets, which also serve as a mounting point for the actuators. The final step was to add a pair of switches near the throttle lever which are used to make manual adjustments when the boat is in motion.

Human-powered Quadcopter Flies Live Tomorrow

May 10, 2011 by Mike Szczys 30 Comments

A team from the University of Maryland will be taking their human-powered helicopter to the air tomorrow. The current flight record for this type of vehicle is just over 19 seconds of flight at a height of about 8 feet. What surprises us about this attempt is that they’re not pedaling just one main rotor. It seems that the most success in man-powered helicopter flight has come from helicopters with a total of four rotors.

The image seen above is a 2009 test of just one of the four rotor arms that will go into UMD’s finished chopper. Fully assembled it will be about 1/3 the size of a football field, dwarfing the autonomous quadcopters we usually see around here. Get the details about the design from the video after the break. It’s interesting to hear [Dr. Antonio Filipone] talk about the need to generate both the lift and the thrust, where human-powered fixed-wing aircraft only need the thrust. He predicts that human-powered helicopter flight is possible, but that it will only lift the aircraft, with little possibility of moving it in one direction or the other.

The team is attempting to grab the $250,000 Sikorsky Prize with their creation. We wish them the best of luck.

Continue reading “Human-powered Quadcopter Flies Live Tomorrow” →

Bit Banging VGA From An SD Card Slot

May 10, 2011 by Mike Szczys 14 Comments

If you’ve got some favorite electronic device that includes an SD card slot but doesn’t have a video out port you may be able to push VGA signals through the card reader conductors. That’s exactly what’s going on above with the Ben NanoNote, a sub-$100 Linux device which we’ve seen using its SD card slot as general I/O before.

The hardware to capture the signals includes a breakout board for the card slot. Free-formed on the other end of that connector card is a gaggle of resistor which handle level conversion for the VGA color signals, with a VGA cable taking it from there to the monitor. The software that makes this happen is a dirty hack, blocking all other functions while it displays a still image. But we’re sure that it can be cleaned up somewhat. Just don’t hold out hopes for full-motion video, this little guy just doesn’t have it in him.

[via Dangerous Prototypes via Slashdot]

Roll Your Own Capacitors – High Voltage Edition

May 10, 2011 by Mike Szczys 13 Comments

[Grenadier] tipped us off about his method for building your own high-voltage capacitors. He thought the paper and foil capacitor project was a nice introduction to the concepts, but at the same time he knew he could produce a much more powerful device.

For the dielectric he is using acetate film. This is the material from which overhead transparency sheets are made. He stuck with aluminum foil for the two plates. Just roll the foil flat with a rolling-pin, use thin wire to minimize the air that will be trapped between the dielectric layers, and make sure the foil plates are at least 4cm shorter than the acetate film on each end to prevent leakage. After rolling and securing the capacitor with zip ties you’ll be ready for the 3nF worth of fun seen in the video after the break. [Grenadier] mentions that this can be improved further if you were to vacuum impregnate the device with beeswax.

Continue reading “Roll Your Own Capacitors – High Voltage Edition” →

Tiny Atari 810 Disk Drive Upgrade

May 5, 2011 by Mike Szczys 25 Comments

Everything gets smaller as technology improves. [Rossum] reduced the space needed for an Atari 810 disk drive by building this tiny replacement. Of course it doesn’t use floppy disks, but takes a microSD card instead. And it doesn’t stand in the place of one floppy drive, but can emulate up to eight different drives. The best part is that [Rossum] went to the trouble of designing an enclosure and having it fabricated via 3D printing in order to look just like a doll house version of the original hardware. It uses an LPC1114 ARM Cortex-M0 microprocessor to translate data transmissions to and from the Atari hardware, storing it on the 8 GB card.

As usual, you’ll soon find the schematic, board artwork, and code up on his git repository soon.