IR Communications Tutorial

July 29, 2011 by Kevin Dady 5 Comments

After seeing our communications via light post , reader [Chris] dropped this handy little link in our inbox. A very good tutorial about using infrared to enable communications between 2 pic micro controllers.

The tutorial covers all the parts you will need, physical wiring and schematics with notes detailing each section of the circuit. It then goes on into basic IR theory, and a simplified push button circuit you can make to see that it is, in fact, working. Once you get the exercise built on some breadboards, he does some software and get some results from it all.

Now in the end this little device was hitting in the neighborhood of 9600 baud, but had to be pretty darn close to each other with a direct line of sight. These are often accepted as a couple of drawbacks to IR technologies. IR, which has never really vanished, is in use on a lot of devices though. The more you know the better off you are.

Join us after the break for a quick video!

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Clocks Built From Old Aircraft Surplus Parts

July 25, 2011 by Mike Nathan 26 Comments

A few years ago, Tube Clock forum member[Sine1040] bought a set of four brand new aircraft indicator units that were built some time in the early 70’s. He had no idea what the units were actually used for, but he did know that he could repurpose them into some pretty slick looking clocks.

He disassembled all four boxes and between them, scrounged enough parts to build three clocks. After gutting the clocks and rearranging the digits, he built a timekeeping circuit using an ATMega8 which is clocked by a DS32 oscillator.

While the time is displayed using the large projection-style digit displays, the seconds are ticked off in the left-most analog meter. Minutes are also represented in the clock’s right-most analog window, swinging the needle from top to bottom as each one passes.

[Sine1040] paid special attention to keeping the boxes looking as stock as possible, with the only external modification being a power plug installed in place of an old grounding screw. The clock is definitely a different take on keeping time, and we think it looks great.

Continue reading to see a quick demo video of the clock in action.

[Thanks Brian]

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Resistor Substitution Box

July 22, 2011 by Brian Benchoff 16 Comments

[Vincent] on the EEVblog forums had an idea for an inexpensive resistor substitution decade box.

The build uses cheap decimal thumbwheel switches he bought on eBay. Each switch is wired up with resistors for each digit, and each switch is wired up in series. The result is a small, easy to read resistor box with a range of 1 Ω to 10 MΩ.

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Followup: Portable SID Player Is Now PC Output

July 20, 2011 by Brian Benchoff 9 Comments

When we first covered [Markus]’ portable SID player we starting dreaming about an alternative universe circa 1987 that included a pocket-sized music player called the Commodore ePod. [Markus]’ updated firmware that connects his SID player to a PC will have to do for now, we suppose.

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[Jeri Ellsworth] Builds A Software Radio

July 19, 2011 by Brian Benchoff 27 Comments

[Jeri Ellsworth] has been working on a direct conversion receiver using an FPGA as an oscillator and a PC sound card DSP. Being the excellent presenter she is, she first goes through the history and theory of radio reception (fast forward to 1:30), before digging into the meat of the build (parts 2 and 3 are also available).

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VGA Pong On A ChipKIT

July 16, 2011 by Mike Szczys 1 Comment

[Nathan] got his hands on a chipKIT Uno32 development board and wrote a Pong sketch that you can play with a VGA monitor. We love the hardware that makes this feel very much like the classic. It uses a collection of resistor-based digital to analog converters to generate the color signals for the VGA protocol. The score for each player is show on a 7-segment display instead of being printed on-screen. And the paddles are made up of a pair of potentiometers.

You’ll remember that the chipKIT Uno32 is an Arudino compatible 32-bit development board. This project shows how the hardware handles, and how easy it can be to generate VGA signals with it if you know what you’re doing.

For those interested in the game physics themselves, [Nathan] provided a nice explanation about ball movement at the bottom of his post. If you need even more details, dive into the code package that he links to.

Infrared Control For Appliances

July 7, 2011 by Brian Benchoff 10 Comments

[RB] at Embedded Lab sent in a great guide on how to control appliances with a remote control using a really clever implementation of a decade counter and IR receiver.

The build itself is very simple – just a relay connected to mains power and a handful of resistors and transistors. The device is controlled with a decade counter and an infrared module usually found tucked away in the bezel of a TV.

When everything is plugged in, the first pulse from the remote switches the relay on, providing power to the outlet. When a second pulse is received, the reset pin on the decade counter is activated, setting the device back to its original off state. It’s a pretty clever build, and could be built with parts lying around the bench.

The project is powered through wall power with the help of a transformer and a 7805 regulator, but we think the size could be reduced with a pass-through power enclosure – the circuit certainly is small enough. In all, a very nice, low component count build.