GSM Controlled Car Without Needing A Microcontroller

July 12, 2012 by Mike Szczys 8 Comments

Nope, no microcontroller here, just a full-blown cellphone used as the brains of this little robot. The secret behind how it works is in the sounds the phone makes. The touch tones, known as DTMF, are monitored by the circuit mounted on the front half of the chassis and are responsible for driving the motors.

[Achu Wilson] built the circuit around an MT8870 chip which decodes the DTMF sounds and uses the BCD output to feed some logic chips. A 4 line to 16 line decoder and an inverter chip format the signals for use as inputs to the L293D motor driver. The video after the break shows him driving the rover directly by pressing number on the phone (like a tethered remote control). But he mentions that it’s possible to call the phone and press the numbers remotely. We assume you need to connect the call manually as we see no way to automatically answer calls.

This is certainly a fun way to play around with the DTMF protocol.

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Nyan Fax Brings The Celebrity Kitty To Your Office

July 11, 2012 by Mike Szczys 20 Comments

Internet blocked at your office and feel like you’re just not getting your fix of Nyan Cat? Don’t worry, you can now use the fax machine to get your fix. [Tom Scott] put together the project to our delight, which will work best if you can find one of those fax machines that uses the continuous roll of paper. But as you can see above, individual sheets will work too. The best part is that Nyan Fax is live for callers from the UK and internationally!

The hack is using something called ‘fax polling’. It allows the sender to set up an on-demand server where any caller will be sent a queue of documents. In this case [Tom] crafted a Nyan Cat document that never ends… you’ll need to disconnect the phone line or pull the pug to stop the printing. See for yourself in the clip after the break. If you’re interested in setting up your own it can be done with the mgetty and sendfax packages on a Linux box.

Just in case you’re keeping score, [Tom Scott] is one of the guys behind the Webcycle.

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The Excitement Of Ice Fishing Now From Anywhere In The World

July 4, 2012 by Mike Szczys 2 Comments

Now you can experience the excitement felt for centuries by ice fisherman thanks to this cellular-capable tip-up.

For the uninitiated a little ice fishing primer may be in order. The majority of what you see above is a standard tip-up rig for ice fishing. Basically it lets you set many baited lines and just watch for a flag to pop up when one of them hooks a fish. Just drill a hole in the ice and drop the line through — the orange frame rests on the surface of the ice.

The add-on here is the grey box which is hiding an Xbee device. A magnet and reed switch (which can be found at the local hardware store) complete a circuit when the flag is down. But if the flag pops up the reed switch opens (or closes, we’re not sure which) and the Xbee sends an alert to a base station, which then converts that to a text message to push to your phone. As you guessed, there’s a video after the break.

Fun and convoluted. But not entirely useless. We’d suggest swapping the Xbee/cellular hardware for a cheap microcontroller/Bluetooth setup. This way you can knock back a few cold ones in the ice house while waiting for the wireless network to alert you via an SL4A script.

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VGA Message Board Displays SMS Without A Computer

June 28, 2012 by Mike Szczys 6 Comments

[Achu Wilson’s] latest creation is a VGA message board which is written to via SMS text messages. This doesn’t sound too interesting at first, until you find out he’s doing this with a microcontroller rather than a PC. All of the complexity is in the code that drives the VGA. He managed to do it without any jitter while using an 8-bit microcontroller.

But first, the cellular side of things. A GSM modem takes care of connectivity. To communicate with the modem [Achu] used an ATmega8. He mentions the he could have used a much smaller uC, like an ATtiny, but this is what he had lying around. When a message is received the ATmega8 feeds the characters to an ATmega16 which is driving the VGA monitor. Rather than deal with the analog voltages necessary to run a color display he simply ganged the three color lines together and drives them from one of the microcontroller pins. This results in white and black which correspond to voltage or no voltage.

You can see him showing off the system in the clip after the break.

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Classic VW Bug Stereo Gets Bluetooth

May 25, 2012 by Caleb Kraft 23 Comments

If any of you deal with older car fanatics, you’ll know that the original dash stereo is a coveted piece of equipment. If they haven’t been removed and replaced with something more modern over the years, they’re usually non functional. [Hadrien] has gone through some trouble to retain his original stereo in his 69 Volkswagen Beetle. First, he did a common hack we see even in modern cars. He added an auxiliary input.

This satiated his desire for modern audio for a while, but he really found the necessity for a cable attachment annoying. He decided he was going to add bluetooth (google translated from french). To do this, he took a pair of bluetooth headphones and tore them apart. Using an old cassette tape as the case, he rebuilt them as something that could be wired directly to his dash stereo. He even kept the mic just in case he wanted to use this as a hands free device.

Being build in 1969, his car stereo doesn’t use a cassette, so he just keeps it in the glove box. This isn’t optimal, but as he says, at least he doesn’t have to plug in his phone.

Getting Great Bootlegs With The BootlegMIC

May 21, 2012 by Brian Benchoff 28 Comments

Go to any concert, show, or basement band practice, and you’ll find someone recording a bootleg. While these live recordings are sometimes fairly high quality, bootlegs recorded with a cell phone usually sound terrible. The guys over at Open Music Labs have a great solution to these poor quality recordings that only needs a few dollars worth of parts.

The project is called bootlegMIC. It’s a simple modification of an electret microphone – the same type of mic found in cellphones and bluetooth headsets – that allows for some very high quality recording in very noisy environments. According to the open music labs wiki, the modification is as simple as cutting a few traces on the PCB in an electret mic and soldering on a cap and a few resistors.

An electret mic contains a small JFET to amplify the signal coming from the microphone diaphragm; the specific JFET is selected by the manufacturer to ensure the microphone has the right gain and response. Usually these JFETs are chosen with the expectation of a relatively quiet environment, and trying to record a concert only results in a ton of distortion. By putting a resistor between the source of the JFET and ground of the microphone, it’s possible to reduce this distortion.

The circuit is easy enough to solder deadbug style, and should work with most cellphones. The guys at Open Music Lab were able to get their mic working with an iPhone, but they’re still working on figuring out the Android mic input. There’s a great demo video showing the improvement in audio quality; you can check that out after the break.

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Scavenging From Consumer Electronics To Make A Flame-powered Phone Charger

May 18, 2012 by Mike Szczys 32 Comments

[Gigafide] just finished building this flame-powered phone charger. The concept is not new. He grabbed a Peltier cooler and used the temperature differential between a flame and a heat sink to produce electricity used by the charger. If you search around here enough you’ll find plenty of candle-powered devices, and a few hacks that use a Peltier device in a bit more interesting way. But we really like his high-production value video, straightforward explanation of the concepts, and ability to source the components in consumer devices. We don’t think you’ll be disappointed by his video found after the break.

The Peltier device comes out of a USB drink chiller. It is supported by a metal stand made from electrical box covers and threaded rod. Underneath he’s using a gel fuel can used by the food industry, and above he’s got CPU heat sink and fan. This setup puts out around 1.5V but he’ll need a boost converter to charge a phone with that. A single AA battery charger meant to power your phone in a pinch is perfect for this application.

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