G'day folks

I'm looking for some ideas for what ought to be a fairly simple project. I am involved in making music in an amateur way and normally I play a 12 string guitar. I've been asked to become involved in some acappella work and I'm one of those people who has no idea what key he's singing in without a guitar to guide me. Once started I'm OK, but the start is the problem. So I need to produce a little gadget which will give out one of 4 notes, A 440Hz, D 146.8Hz, G 196Hz, and C 261.6Hz. I have a decent frequency counter and a DSO so aligning a circuit won't be a problem, plus of course I have an electronic tuner for the guitar that I can compare notes to.

Any ideas will be gratefully received.

Cheers

Barrie Davis

 

Frequencies of that precision will require use of a microprocessor to generate them. Do you have programming and pcb-making facilities?
What frequencies does your tuner produce (you can tell I'm not a musician )?

 

You could use a voltage controlled oscillator (VCO), something like a 8038. with four buttons each providing the correct voltage for your required frequency. You'll need to buffer /amplify the output to correctly drive your load (speaker?)

HTH Steve.

 

A very simple approach would be to use an oscillator such as the NE555/LMC555 etc. in the astable configuration.

Above is from Bill Marsden's discussion of the NE555 on this forum
http://forum.allaboutcircuits.com/showthread.php?t=74036

You can then have four independent pots for R2, one for each note, switching among the four selections with a four position switch. The output is on pin three. What might bother you is that rectangular pulse out of pin 3 is rich in harmonics and that the spectral distribution is different for each note (because the duty cycle would change). Note: Couple pin 3 to your speaker through a large capacitor with the+ end connected to pin 3 and the - end connected to the speaker.

Of course you can also use this technique with many other kinds of RC oscillator.http://bit.ly/1pozJuR

 

A very simple approach would be to use an oscillator such as the NE555/LMC555 etc. in the astable configuration.

Can't get the image to show up here, so please click to see this image:

Above is from Bill Marsden's discussion of the NE555 on this forum
http://forum.allaboutcircuits.com/showthread.php?t=74036

You can then have four independent pots for R2, one for each note, switching among the four selections with a four position switch. The output is on pin three. What might bother you is that rectangular pulse out of pin 3 is rich in harmonics and that the spectral distribution is different for each note (because the duty cycle would change). Note: Couple pin 3 to your speaker through a large capacitor with the+ end connected to pin 3 and the - end connected to the speaker.

Of course you can also use this technique with many other kinds of RC oscillator.http://bit.ly/1pozJuR

 

I like the idea of 555 and similar oscillators, but If I were a musician I think I'd want greater frequency stability than a simple VCO or RC oscillator is likely to provide .

Edit: Do you want a sine-wave output or could you tolerate a square-wave or triangle-wave (with all their harmonics)?

 

http://www.indigo.com/tuning_forks/music/?osCsid=eciq2gkgcm2nl6grvf3idmadi3#.U61Gr5lOk94

Why build an oscillator with all the inherent difficulties of calibration and freq drift. Never knowing for sure if you are "in tune" or not. The cost of the forks offered by the linked company is very affordable and they probably would be needed anyway as a standard for calibrating your oscillator.

 

What you're describing is an electronic pitch pipe. They're commercially available. Here"s one:

http://pockettones.com/

 

what about a ready made chromatic scale generator Ebay

 

Iphone or android. There's an app for that...

 

G'day folks

Thanks very much for all the helpful suggestions. I wasn't aware of the devices available, although I did search Google originally. Obviously I didn't use the right description. I have placed an order for an electronic pitch pipe from JustGottaSing which is quite inexpensive, although of course shipping to Australia doubles the price.

When time permits in amongst the 20 or 30 projects I have on the go I will experiment with the 555. Because the quality of the sound is unimportant, only the pitch matters, it seems like that would do the job.

Thanks once again.

Barrie Davis

 

How about one of these:

 

I have placed an order for an electronic pitch pipe ...

Maybe that will be more handy than just using a smartphone or iPod, but I'm curious why you didn't try an app first. Assuming you have a smartphone, tone generators are free and you'd already have it to try while you wait for your order to arrive. If you're on stage, you're more likely to have your phone in your pocket than your pitch pipe. Just my 2¢.