Variable frequency of analog signal

Discussion in 'General Electronics Chat' started by acheron, Apr 13, 2016.

  1. acheron

    Thread Starter New Member

    Apr 11, 2016
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    Hi guys, so one generic question. Lets say that i have voltage f=1kHz and i want to be able to drop it with potentiometer all the way to f=100Hz and all the frequencies in between, and amplitude has to stay the same. Maybe it is stupid question but I don't know if it is even possible?
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
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    Welcome to AAC!

    You need a frequency divider, not a voltage divider. What type of waveform?
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Yes it is possible and has been for quite awhile. It is even quite easy to do today with a modern DDS chip. Check out the AD9850 as just one example of such chips.'

    You could use your relatively low frequency source as a clock, but it might be easiest just to buy a module with a clock crystal and synthesize all of the frequencies you need. Here is an example I posted last last year: http://www.electro-tech-online.com/articles/demo-assembly-code-ad9850-dds-signal-generator.755/

    John
     
  4. acheron

    Thread Starter New Member

    Apr 11, 2016
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    Thanks jpanhalt, I had no idea where to look. Now I have starting point :D
     
  5. acheron

    Thread Starter New Member

    Apr 11, 2016
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    It is a sine wave
     
  6. Alec_t

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    Sep 17, 2013
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  7. AnalogKid

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    Aug 1, 2013
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    Is there amplitude or phase information in the incoming sine wave that must be preserved or reproduced, or can the incoming sine wave be used as a clock for a waveform generator or synthesizer?

    If the latter, then there are several digital techniques that will achieve this, including some with a tracking output lowpass filter to re-establish the sine shape.

    If the former, then you are looking for frequency subtraction (heterodyne), like the front end of a radio receiver only at much lower frequencies. As the ratio of the output and input frequencies changes from 1:10 to 1:1, this goes from difficult to impossible.

    ak
     
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Why not start out with a simple DC voltage, you can create a frequency of your own from 100 to 1000. What exactly is your goal. Do you want to feed in any frequency and get something that is a given fraction lower? Do you want it to retain the same wave shape (square, triangle, sine, human voice, ...). I think you have some more explaining to do.
     
  9. acheron

    Thread Starter New Member

    Apr 11, 2016
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    Ok, so I'm planning here to do pedal for guitar. My plan is to give pedal a signal with specific freq and to be able to drop it to approx 100 Hz. I'm guessing the numbers here. here is the link so you can see what i mean(bomber effect).
     
  10. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    If you have an unknown frequency and you want to drop it a fixed amount, say 100 Hz, then looking into "mixers." They will give you the sum, which you don't want, and the difference, which you want.

    John
     
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