Wireless

[elec_student]

Hello all,
          I am new to this site and it looks pretty cool so I hope I can learn alot here.  I am an electronics engineering student and for graduation we design and build anything we want, that has to do with electronics that is.  I have been playing guitar for about 7 years now so I choose a multi-effects pedal for my project.  I want to include a volume control, about 12 ports for other pedals, maybe a graphic equalizer and I hope to do a wireless patch to the guitar.  I looked into maybe using modules for the wireless.  I was wondering if anybody could point me in the right direction as to what I should use for the wireless. I don't really need that good of distance range but very low noise and interferance would be great.  Ok so thanks for taking the time, hope to get some replies.   Have a great day.

                                                               ~Mark~

[soundcollage]

Hello,  and welcome to the forum. I may be mistaken, but I believe wireless tech. needs to be regulated by the FCC and therefore difficult for the DIY'er.  I'm not saying that it can't be done or that you will be caught, but it might be embarassing at a gig when the feds arrive  because your guitar solo has been blocking fire or police bandwidth. If someone else knows diferently let me know, because I would not mind attempting such a project.

[Jaicen_solo]

It is possible to make a super simple FM transmitter using 2 transistors and a small radio receiver.
The problem is making it sound good without hiss and interference. FM transmitters are relatively low frequency, so they tend to use pre-emphasis, where high frequencies are boosted at the input, transmitted and then attenuated at the end. A crude form of noise reduction. It's also possible that you can pick up other radio stations (though the transmitter I used didn't). At the end of the day, FM is just not good enough for this purpose. With regards to the cops showing up, I wouldn't worry. Unless you really boost the output the range is quite limited, about 10 meters without an aerial (at ground level).
For a good quality signal you need to go to VHF or better, UHF transmitters. Usually these use PLL synthesis to get a stable frequency. These have the advantage of good audio quality, but they are expensive.  If you do work out a wireless system, there'd be a lot of people interested here, I just think it's beyond the scope of most DIY'ers.

[scratch]

I'll echo Jaicen_solo's comments ... I've built a couple of super simple FM transmitters for wireless microphones (my wife an avid birder, wanted to bring the sounds of birds into the house, we live in the country ...) and the frequency drift is awful! Definetly requires some kind of PLL to lock the transmission.

[niftydog]

Just a word from the wise here; I too recently underwent the same type of project for my final assessment and I have but one piece of advise for you as you set out on this journey:

Don't try to do too much. Do enough just to pass the subject!

I bit off a bit too much and it haunted me for ages. Where as I should have just taken the easy route, passed the course with one hand tied behind my back and moved on.

[robbiemcm]

What? But surely this is the mark that employers and such will care about. I can understand that more if you said it about school. But surely for this he should be trying as hard as he can?

[Jaicen_solo]

No, niftydog is right. I did a similar thing myself. I investigated the factors affecting frequency response in guitar pickups. I wanted to build my own and I thought it would be fun and interesting.
As it turned out, there was a lot of work to do and I didn't really have time to do it with all the other stuff they made me work on (like, ermm, business studies? On a Music Tech degree??). I could have just mixed and mastered a track and got a first instead of busting my ass (I even went 300 miles to visit Bareknuckle Pickups) and getting a 2:1.
Still, live and learn

[niftydog]

All the potential employer cares about is that you've done the course. I doubt anyone has ever had a job hinging on the strength of their final project - in fact, I doubt many empolyers have even taken an interest in the specifics of a potential employees final project. Sad, but true.

[AdamB]

I think in order to make a decent working wireless system (without loads of hiss and interference) it would have to be digital so that the computer in the wireless reciever can cut off noise added to the radio signal during transmission. Making a digital transmitter and reciever is a dodgy area, as your input and output of the wireless system is analouge, so you'd need analouge -> digital converters and all that jazz, which means building a digital computer circuit to do it for you, which I have no idea how that works, but sounds really hard.

-Adam