I have been playing around with nerdkits for a while, but I never really created something usefull, much less creative. Last year I went to a Coheed and Cambria show, and noticed that they didn't have any cables coming from their guitars, but rather an antenna strapped to their guitar straps, and that gave me an idea to create my own wireless guitar, plus a neat twist(If its possible).

After much procrastination I did some research and learned that the most effective way to transmit the frequencies is via radio. I made an FM transmitter before, but never a reciever. I don't really need to much range for the transmitter, about 5-10 yards would be more than enough.

I know that a simple transmitter/reciever is simple to do, and doesnt even require Nerdkits, but what I would LOVE to do is add somesort of "digital auto tuner" where I can automatically choose to either raise/drop a half or full step, that reads the voltage fom my guitar, sends it through op amps to the ADC, finds out which frequency(note) I'm playing, and use a function generator chip to create the appropriate sine wave, and send it out through the transmitter.

It seems a little out of my grasp, but I stumbled across a DIY guitar tuner project on the webs who uses the Atmega, and it seems easy enough to adapt their code to what I need. project is here

I'll update this with any research I come across, any suggestions would be awesome :)

I found an IC Sine Wave Generator

Feed back on it would be awesome, especially if you have any other ideas/ways to produce a Sine Wave digitally

Hi awkwardsaw.

wireless Guitar: You're heading into a world of pain with this project, licenses are required to operate radio transmitters in most countries, USA and UK included, and compliance with the regulations can be difficult expensive. Also, you could cause disruption to emergency services, aircraft, military etc, possibly resulting in loss of life, I'm sure you wouldn't want that. Buy the hardware that's already Aproved for use in your country!

Bluetooth Guitar: One way to use your NerdKit would be to digitize the guitar signal and use an existing standard like Bluetooth to transmit the data, then use a DAC to convert the data back to audio again. You'd need an ADC chip, the ATMega168's onboard ADC is only 8 bit, you'd need at least 12 bit, 16 bit would be better.

Then you'd need another Nerdkit for the receiver, and a 12 or 16 bit DAC, and use of a 200MHz osciloscope to set it all up.

And after all that trouble and expense, a few feet of copper wire would be better, cheaper, and infinitely more reliable.

Auto Tuner (pitch changer?): you're talking about complex digital signal processing here, and the ATMega MCUs aren't really up to the job. You need something with a 16bit ADC/DAC, several MB of memory, and a much higher clock speed to do this. Having said this, I'd be very interested in seeing what you come up with if you decide to proceed with this.

Guitar to MIDI: Perhaps one area you could look into is guitar-to-midi processing. All you need is a preamp to boost the guitar's (or bass's) signal to a suitable level for the ATMega's ADC to work with, and a MIDI breakout board (http://www.sparkfun.com/products/9598). The ATMega168 already has the ability to read/write to MIDI via USART, you might have to do some level shifting though. All the software needs to do is time the input signal zero crossings (tells you the root frequency of the note), and send the appropriate MIDI note on/off command.

This setup would be ok for single notes, but chords would totally confuse the software. Ideally though, you need a seperate pickup and processing for each string.

For inspiration, check this: http://www.youtube.com/watch?v=bWaNlcXuGmI

Good luck!

Sine wave generator: Digitally, you can only ever produce an approximation of a sine wave. As a designer, your job is to determine how close you need to get.

It's easy to get the ATMega168 to make something close to a sin wave, just switch one of the pins on and off at the right frequency and filter the output. Connecting the output pin to ground via a capacitor will effectively short out the high frequencies present on the square wave, leaving you with a smoother signal. an active audio filter will give you a cleaner sine wave. How much work you need to do depends on how perfect you want your sine wave.

If it's just for tuning your guitar, then personally, I think the square wave is good enough.

Please bear in mind though, there's more to tuning a guitar than you might think. With all the electronics and software and software available today, I still prefer to tune my guitar by ear.

Good luck!