[sdiy] Using DG-series analog switches for PWM VCA
rutgervlek at gmail.com
Wed Jun 13 12:22:37 CEST 2018
I've had an SSI2164 running at a fairly low supply voltage, certainly
within pedal ballpark voltages.
Op wo 13 jun. 2018 12:06 schreef Tom Wiltshire <tom at electricdruid.net>:
> Generally speaking I’d be of exactly the same mind, David, but in this
> case this is a pedal project, so it’s a 9V single supply, which is pretty
> borderline for a 2164. Or pretty much any other obvious VCA chip except the
> LM13700, to be honest. The LM13700 is out because the chances of it *not*
> thumping with a choppy square wave modulation signal like I’m using are
> going to be minimal. Happy to be proved wrong if anyone knows a way though.
> I could generate a bipolar supply I suppose, but then that requires
> another chip and makes things more complicated again.
> Electric Druid
> Synth & Stompbox DIY
> > On 13 Jun 2018, at 04:22, David G Dixon <dixon at mail.ubc.ca> wrote:
> > 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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