New and improved Potentar

We like what we’re seeing and hearing with [Dorian Damon's] newest version of the Potentar. This is revision 2.0 of the instrument we saw in a December links post. He calls it the Potentar, since it uses a linear potentiometer in a way similar to how the frets on a guitar work (Potentiometer + Guitar = Potentar).

The first thing you should notice is the case upgrade. The original used what looked like unfinished scrap wood, but finished wood of this case really makes the thing look like a traditional instrument. With this design he loses the Arduino in favor of a standalone ATmega328 chip. You’ll notice knobs and a switch on the face of the body. This allows for selecting a couple different kinds of scales and turning the power off. The linear potentiometer and sewing machine button are the same as before. After the break you can catch his description and a quick performance thanks to the audio jack for patching it into an amp.

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Motion sensitive RGB lamp can standby for 3 years

Ooooh, nice enclosure! This is a little motion sensing lamp which [Krazatchu] built a few years back as a Mother’s Day gift. The PIR sensor is easy enough to see as the white dome on the front of the case. But look closely below that and you’ll see the LDR which it uses to keep the thing asleep during the day. This is intended to save on batteries but the original version still ate through them like crazy. This year he gutted it and worked out a much more power-friendly design.

He moved to a TLC1079 OpAmp which greatly reduced power consumption when reading from the PIR sensor. The microcontroller was also upgraded from an ATtiny13 to an ATmega328, making the new version Arduino compatible. It puts itself to sleep and keeps the lights out during the day, drawing just 0.08 mA. When driving the RGB LED the lamp pulls about 50 mA. That should still last a while on three AA batteries but we’d still recommend using rechargeables.

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Surround Sound system controller replacement includes home automation

[Neoxy] always wanted surround sound for his computer, and one day he managed to get a hold of a dead 5.1 system. Why buy one when you can repair someone’s rubbish, right? That turned out to be easier said than done, but after several false-starts he managed to resurrect the audio system by replacing the microcontroller.

We find his trouble-shooting technique interesting. The amp would power up without a hitch but no sound would come out of it. So he took a headphone cable and used the L and R conductors as probes. That cable was fed from an MP3 player, and by touching the probes to the audio inputs for the pre-amp and amplifier circuits he could get great sound out of the speakers. Reasonably certain that those boards were working fine he narrowed down the troubles to three chips that mix, select inputs, and control the system.

A lot of prototyping with an ATmega328 and an Arduino led him to the functionality you see in the video after the break. Not only did he get the system working, but he’s using the Arduino to add Internet control for the device.

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Motor controller also does nyan cat

As a freshman at UC Berkeley, [Keegan] has been helping out with his school’s Pioneers in Engineering program that gives high school students some hands on experience with engineering principles, usually by building robots. This year, [Keegan]‘s project is a motor controller that just so happens to play the nyan cat song over the motor PWM output.

The motor controller is meant to replace the Pololu simple motor controller the PiE team is currently using. Onboard is an H-bridge chip and an ATmega328 that takes commands from an I2C bus. The ’328 is loaded up with the Arduino bootloader making the firmware very accessible – a good thing for the high school students that will be building and programming these robots.

[Keegan] put up the Eagle files for the board up on the PiE Wiki. For now, just enjoy the dulcet tones of the pop tart cat theme song after the break.

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POV clock spins light filter instead of LEDs

This hard-drive based POV clock is a treasure trove of great design choices. Now, we’ve seen a bunch of spinning clock builds. Several of the hard drive versions use slits cut in the platters to create a display by illuminating an LED behind those slits at just the right moment. This is a similar idea but [Jason Hotchkiss] ditched the platters all together and replaced them with a light filter. The filter disc has digits 0-9 as well as a colon (not seen above because the colons blink each second). As this disc spins, the Arduino compatible controller lights up LEDs in the eight digital positions to illuminate the correct number.

The filter is made from an etched copper-clad disc. This is a great choice because the fiberglass substrate is strong, light weight, translucent, and available. The filter idea also means you don’t need to get power or data to a spinning platform. [Jason] has also designed a very impressive controller board that is the same size as the footprint of the laptop hard drive he’s using. Check out the video after the break to see his description of what went into the hardware choices he arrived upon. [Read more...]

Microcontroller based audio volume level compressor

In an effort listen to his music on shuffle without the need to touch the volume knob [Mike] build his own automatic volume leveling hardware. He knows what you’re thinking right now: there’s software to do that for you. But building the feature in hardware is a great stepping off point for a project.

He started the prototype using LabVIEW along with a Mobile Studio development board and a Bus Pirate. This project will be a mix of digital and analog components and it’s a bit easier starting off the exploration with these tools rather than jumping right into the AVR code.

The circuit will sample the incoming audio, modify it accordingly, and output the result. The output side is where the Bus Pirate really shines. He’s using some MCP42010 digital potentiometer chips to make the necessary changes to the levels. They communicate via SPI and it’s nice to have the Bus Pirate’s terminal to issue commands without the need to reflash a microcontroller.

[Mike] made a video showing an audio waveform with and without the hardware leveling. Sound quality is still great, and each clip is played at a reasonably comfortable listening level. We’ve embedded that demonstration after the break.

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osPID: the Open Source PID Controller

Need PID control in your next project? Perhaps this little beauty can help. It’s an Open Source PID controller that also follows the Open Hardware guidelines. [Brett Beauregard] based the project on the newly minted Arduino PID library which he wrote. In the video after the break [Brett] takes apart the device, walking through some of the ways this might be hacked. If you want an overview of every part of this project to-date the best resource is probably his personal blog post.
The front circuit board is the meat and potatoes of the device. It hosts the user interface in the form of buttons, LEDs, and a graphic LCD screen. You can also see the USB mini-b connector which gives you access to the Arduino compatible ATmega328 microcontroller on the back. There is also a piezo buzzer for your alarm needs.
The prototype that [Brett] shows off uses pin connectors to join the main board to the two daughter boards. Unfortunately, the production model moved to dual-sided edge connectors. That’s fine if you you’re using it in its stock condition, but it makes it a bit harder to replace those boards with your own hardware. None-the-less, we love to see great Open Hardware projects brought to market! [Read more...]