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

[Andy Talbot <andy.g4jnt@gmail.com>]

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

www.g4jnt.com

 

 

On 25 June 2011 23:17, Graham <g8fzk@g8fzk.fsnet.co.uk> 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..