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Re: LF: Spec-lab audio gen - sweep tone - how 2 ?

To: [email protected]
Subject: Re: LF: Spec-lab audio gen - sweep tone - how 2 ?
From: Andy Talbot <[email protected]>
Date: Sun, 26 Jun 2011 08:39:53 +0100
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Graham -
you don't say if you want a hardware solution or a software one.
 
In hardware, you could use an op-amp  VCO design, common in teh old music synthesizers of yore.   I don't have the circuit configutation to hand, but an Inet search would surely throw it up.   Or there is the VCO in the 4046 CMOS PLL chip.  Generates a square wave, unfortunately, which I assume you would need to shape.  
 
Or there is the sine/triangle/square function gen chip - again can't recall the number off hand.   That has a voltage control input as far as I recall from the dim-past.
 
If you generate a sweep at a high clock rate this can be turned into a very clean sine using the 5089 DTMF generator chip,  set for a single tone output .   Use your swept clock in place of its crystal oscillator input - I've used this in the past.
 
Or a PIC with sine lookup table programmed to generate a sweep, and R/2R ladder on the output.
 
But now, a software solution wins hands-down, using a soundcard to generate the audio.   If you have the capability to repeatedly play .WAV files in a loop, then record a sweep to .WAV and do this.   I can generate suitable wav files and can send you the simple prog if you want.
 
Andy
 

 
On 25 June 2011 23:17, Graham <[email protected]> wrote:
Spec-lab  audio  gen  - sweep  tone  - how 2 ?
 
Is it  possible to  arrange  for a  single  tone  o/p  to  be swept  from a  start  freq  to  stop  freq 
 
ie   100  Hz  >  4 KHz  , with   linear  or  log  frequency  change  ?
 
Can  various  options  but not a  sweep  tone  function ? 
 
Tnx _ G..



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