A/D freq change

[EmeraldW]

I have a request to build an a/d converter for a guitar that would change the frequency of the incoming signal by a set amount. I was thinking that a microcontroller might be able to handle this but wanted to get some input.

Here is an example of what he needs:

Guitar pickup to a/d converter -> divide the sampled frequency by 2 and output as a digital signal or back through a d/a converter. The sample rate needs to be as high as possible.

Any thoughts?

 

[Nigel Goodwin]

Look at DSP's - although why doesn't he just buy one?, they are commercially available at low prices.

 

[EmeraldW]

I'll check those out. If they will work, might not have to build something however I need to do it for six different inputs and build it into the guitar body.

 

[Nigel Goodwin]

I'll check those out. If they will work, might not have to build something however I need to do it for six different inputs and build it into the guitar body.

Check out Behringer pedals, they do two Octaver models, both have adjustable outputs one and two octaves lower - the cheaper one is only £20 odd.

 

[EmeraldW]

Yeah I have pedals that will do it, but for this application each string has its own single coil pickup with its own output. All of the strings will be tuned to a set frequency and then each input will multiply or divide it before it is sent out the output.

 

[EmeraldW]

View attachment 63331

This adds frequency but can something similar subtract?

Staying on the micro controller subject, if connected to the A/D of a pic, what value would it return in a sample? The datasheet is not real clear at my level of experience with the ad converter.

 

[Brevor]

This adds frequency but can something similar subtract?

That circuit is just a filter it will boost the signal level at certain frequencys but it will not change the frequency.

Staying on the micro controller subject, if connected to the A/D of a pic, what value would it return in a sample? The datasheet is not real clear at my level of experience with the ad converter

It would return a binary number (10 bits) that represents the voltage level of the signal at the instant the sample was taken. Frequency sampleing is not usually done with an ADC.

 

[EmeraldW]

I'll go back to looking at DSPs then. I've gone through a couple data sheets for them but I can't get my head around how to attack one.

 

[Nigel Goodwin]

I'll go back to looking at DSPs then. I've gone through a couple data sheets for them but I can't get my head around how to attack one.

I believe there are various examples at MicroChip for their dsPIC series, there might be something similar to what you're looking for?.