Organ pedals fill in when your bass player is missing


Since his string bass player isn’t always around [Antoine] built his own electric bass stand-in using the pedals from an old organ. The project — which he calls the Organ Donor — was inspired by a similar standalone organ pedal bass project. That instrument was built using a 555 timer to generate the sound. But [Antoine] has a little more room for growth as he’s using an old microcontroller development board to generate sound.

The octaves worth of pedals were pulled from an old broken Yamaha A55 Electone organ. After extracting the assembly from the instrument he built a nice wooden case around it. This doubles as a stand for the amplifier which broadcasts the sound. An old Freescale development board is wired up to twelve of the keys (the top C is unused). It generates a square wave at the appropriate frequency for each key. This signal is fed through a low-pass filter before being routed to the audio jack on the back of the case.

Future improvements include building an amplifier into the pedal assembly. We would also love to see different signal processing to expand the range of sounds the pedals can generate. We’re not sure of the capabilities of that microcontroller, but it would be neat to hear tone generation using stored samples.

Building touch sensors from digital barometer chips

A couple of Harvard researchers have developed a method of using digital barometers as a touch sensor. The good news for us is that they’ve open sourced the project, including Eagle board files, firmware, and details about the materials they used.

The digital barometers were chosen for their characteristics, availability, and low-cost. The sensor uses an array of Freescale MPL115A2 chips, a MEMS Barometer designed for use in altimeters. The mass production makes them cheap (Octopart found some in single quantities for $1.71 at the time of writing). The chips are soldered onto a board which is then cast in rubber. This distributes the force while protecting the sensors. The video after the break shows them standing up to rubber hammer blows and supporting a 25 pound weight.

There are a few tricks to reading the array. The first is that the devices are designed to be used one-to-a-project so they have a fixed i2 address. A separate chip must be used to address them individually. But one it’s up and running you should be able to use it as feedback for the fingertips of that robot arm you’ve been building.

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Very inexpensive RF module tutorial

Let’s say you need a way to make a project wireless, but don’t have the scratch for a ZigBee or its ilk. You could use IR, but that has a limited range and can only work within a line of sight of the receiver. [Camilo] sent in a project (Spanish, translation) to connect two devices via a wireless serial connection. As a small bonus, his wireless setup is cheap enough to create a wireless network of dozens of sensors.

[Camilo] used the TLP434A transmitter/receiver combination to get his wireless project off the ground. These small devices only cost about $5, but being so inexpensive means the hardware designer needs to whip up their own communications protocol.

For a microcontroller, [Camilo] chose a Freescale MC9S08QC, a pleasant refrain from the AVR or PIC we normally see. After making a small board for his transmitter, [Camilo] had a very small remote control, able to send button presses or other data to a remote receiver.

After the break, you can see a short demo video [Camilo] posted of his wireless transmitter turning on an LED attached to his receiver. Unfortunately, this video was filmed with a potato, but all the schematics and code is on his web site for your perusal.

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Monitoring a clothes washer with an accelerometer

[Viktor's] washing machine did a good job of cleaning his clothes, but it kept a bit too quiet about it. The machine doesn’t have an audible alert to let him know the cycle has finished. He decided to build his own alarm which can just be slapped on the side of the machine.

You can see that a couple of magnets hold the board to the metal housing of the washer. The board doesn’t actually connect to any of the machine’s circuitry so this should work about equally as well for any unit. The detection is based on motion, thanks to a Freescale MMA7361 3-axis accelerometer. When he starts a load of wash he flips the power switch for the board on. The PIC 12F683 that drives the device starts monitoring the accelerometer for changes. If it goes for more than about one minute without reading motion the piezo buzzer starts beeping. It’s a fun and easy solution along the same line of this oven pre-heat alarm add-on.

Spectrum analyzer users custom characters on an HD44780 display

[Camilo] built a spectrum analyzer to use with his audio system (translate). The hardware is quite simple, using an op-amp, microcontroller and LCD display. He chose an LMV324M low-voltage op-amp which connects to the incoming audio signal and feeds its output to the microcontroller’s ADC. In this case, he chose a Freescale microcontroller from the HCS08 family which is running at 20 MHz. This gives the project enough speed to properly analyze the incoming audio. He mentions that he’s following the guidelines set forth in the Nyquist-Shannon sampling theorem and using the Fast Fourier Transform when processing the samples.

This isn’t the first time we’ve seen a character LCD used as a display for a frequency analyzer. This other ATmega8-based rendition supported several different screen layouts. These displays have enough RAM to store eight custom characters. Each character is 5×8 pixels, lending eight levels to each character for a total of 16 for each column seen above. We love the simplicity of the hardware in the project but we wouldn’t mind seeing an additional potentiometer to fine-tune how the data is displayed on the screen to take advantage of its full range. See the project in action in the clip after the break.

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The Firebird32, a new dev board on the block

Here is yet another development board to add to your list (If you are into keeping lists), introducing the Firebird32. There seems to be no end to the production of new development boards, following the current style the Firebird32 comes in the familiar Arduino form factor to fit all of your Arduino shields.

The Firebird32 from [Wytec] is build around the 32bit Freescale Flexis MCU [MCF51JM128] running the Coldfire V1 core commonly found in industrial and medical equipment. We were kindly donated a board before release, the first thing that we noticed was  the onboard 8×2 segment LCD which makes the perfect debuging tool. The board along with fitting standard Arduino shields has extra input headers for a keypad, an accelerometer and an extra communication header (IC2/SPI/SCI). It’s also sporting 8 x 12bit analogue inputs, external 32k EEPROM, an RGB LED, a buzzer and an extra push button. The Flexis chip along with the beefy 32bit processor can run at a clock rate up to 48Mhz using PLL and has an integrated USB port, all of this for under $30.

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Put your ARM skills to the test with the Freescale Make It Challenge

Throw down your mad skills and you might win some cash while you’re at it. [Zeta] tipped us off that Freescale just announced a new challenge. They call it the Make It Challenge and it centers around their 32-bit Kinetis microcontrollers. These are ARM Cortex-M4 chips and if you’re selected to compete they’ll offer their development hardware at a discount for you to get started.

You’ll need to jump through a few hoops. To be considered as a contestant you’ll need to preregister, cruise through some online training, and complete a quiz. From there, just come up with an idea and submit a design paper as the first round of competition. Ten finalists will rise from the group and take their design through to completion for judging in the fall. The top three will get some serious cash ($11,000 for first place) and be treated to an expense paid trip to Austin, Texas.