[sdiy] Using DG-series analog switches for PWM VCA

[David G Dixon]

This sounds like a job for (is it a bird, is it a plane) 2164!!! 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of Tom Wiltshire
> Sent: Tuesday, June 12, 2018 10:33 AM
> To: synth-diy at synth-diy org
> Subject: [sdiy] Using DG-series analog switches for PWM VCA
> 
> I've been working on and off on a "stutter pedal" design. 
> This is basically a severe volume-chopping tremolo effect. 
> I've experimented with using FETs to do the signal muting, 
> but wasn't happy with it. So I thought I'd try a PWM VCA, 
> since I'm controlling the mute signals from a micro 
> controller anyway - unlike the FET mute, I'd actually get 
> some control of the volume level.
> 
> The chip I decided upon was the DSG413LE:
> 
> http://www.farnell.com/datasheets/2311996.pdf
> 
> Since the PWM needs to be at a reasonable frequency, I'm 
> unlikely to have massive control over the gain (9-bit PWM at 
> 62.5KHz would give me -54dB attenuation before 'Off"). But 
> since the alternative was a FET that was basically "on" or 
> "off" this still represents an improvement!
> 
> Has anyone else done anything like this? Do you have any 
> experience to share or gotchas that I should avoid? How do 
> the DG-series chips compare with the old 4066 circuits that 
> I've seen this technique used with?
> 
> Thanks,
> Tom
> 
> 
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