Frequency Converter

[z4lis]

I'm looking to convert some sort of sine wave from one frequency to the other. The only way I can conceive of doing so is to use a freq->volt and volt-> freq or through mechanical means. Is there a simpler way to do it?

Note: I'm not very well-read or experienced with electronics, so I expect any answers I get will give me more questions. :/

 

[Hero999]

That question is far to vague.

Are you talking about power of signal?

A higher or lower frequency?

 

[z4lis]

I need to be able to take the AC current in one circuit, lower its frequency, and use that modified current as a source in a different circuit.

I'm not sure if that helped, but... it was an attempt.

 

[Hero999]

You still haven't given enough information.

Voltage?

Frequency?

Current?

This is likt trying to get blood out of a stone. . .

 

[z4lis]

Frequency will probably lie between 100-2000 Hz. The desired effect of the device is to take an audio signal and lower it by an octave. As far as current and voltage, I can't really say. I plan on putting this into a guitar for a school project, so it'll be whatever unamplified pickups are putting out.

 

[Nigel Goodwin]

So why didn't you say this in the first place?, your requirements bear no resemblance to your original question.

However, it's NOT a trivial project, not if you actually want it to be useable - I would suggest you buy one, they are commonly available in pedal form - check 'The White Stripes' who use one.

 

[VISN]

As a project, what would I be doing, BTW?
Not for music, but for voice frequencies?

Use a dspic to FFT it, do the fancy processing, and then DAC it back out? Is that how voice changes work, ain't it? Hmm, I've been thinking to try this out in Delphi on the PC, and then on a dsPic. I know of the holtek voice changers that did not take of.

 

[Hero999]

Digital signal processing is the only good way of doing it.

The waveform is recorded, then played back at a lower rate.

Getting good quality in real time is hard because you've got to splice the recording when the waveform crosses 0V.

You could even sample the input at 80kHz so you could listen to bats.

 

[picbits]

If it was a single pure sine wave then it would be realtively easy. Introduce any distortion or even a simple chord and it gets a lot harder.

 

[Hero999]

The problem is it seems like it's not just a simple sinewave. He talks of putting it in to a guitar which won't produce a single sinewave but a complex wave.

 

[mneary]

The goal to reduce the signal by 'an octave' should lead to some interesting options.

But since the signal is coming from a guitar (probably multiple strings) it gets complicated really fast.

 

[peter5355]

Voice Changers

As a project, what would I be doing, BTW?
Not for music, but for voice frequencies?

Use a dspic to FFT it, do the fancy processing, and then DAC it back out? Is that how voice changes work, ain't it? Hmm, I've been thinking to try this out in Delphi on the PC, and then on a dsPic. I know of the holtek voice changers that did not take of.

Newbie needs your help please Holtek done a IC Ht 8950 16 pin and 18 pin can anybody help me find circuit diagram for the 18 pin

 

[cdstahl]

Digital signal processing is the only good way of doing it.

The waveform is recorded, then played back at a lower rate.

Getting good quality in real time is hard because you've got to splice the recording when the waveform crosses 0V.

You could even sample the input at 80kHz so you could listen to bats.

ah, but a lower rate means a 1 second clip now takes 2 seconds to play. He want to change pitch, but probably not time.

 

[Hero999]

He doesn't have to change the time as well.

You splice the recording on the fly so it won't affect the speed.

Suppose you splice sound sample in to 100ms chunks, throw away every other chunk and stretch each chunk to 200ms. This will reduce the frequency by half and keep the length of the sample the same. The problem is you need to be careful where you splice the sample. You need to do it where the waveform crosses 0V and make sure the beginning of the next chunk is slewing in the same direction as at the end of the splice. If you don't do the splicing right, you'll add a lot of noise and distrotion and it'll sound horrible.