[sdiy] Photodarlington Optocouplers

[Kyle Stephens]

I take it this is something an output cap wouldn't readily fix :[


Vactrols do have their uses alright. I had some fun a while back using one as a cheap expo converter in a barebones synth I breadboarded. The slewed photocell response made for an 'envelope' and 'glide' built right in.

I even made a highly detailed schematic just now, heh:

http://i10.photobucket.com/albums/a102/erschlagener/ghetto_schem.jpg

Cheers,


_Kyle


--- On Mon, 4/19/10, Paul Perry <pfperry at melbpc.org.au> wrote:

> From: Paul Perry <pfperry at melbpc.org.au>
> Subject: Re: [sdiy] Photodarlington Optocouplers
> To: synth-diy at dropmix.xs4all.nl
> Date: Monday, April 19, 2010, 6:57 PM
> Unfortunately, for most DIY audio
> applications, the rapid response of the H11F3 and similar is
> a disadvantage.
> The great strength of the traditional CDS vactrol is
> that it smooths out the control signal.
> But I imagine the H11F3 would go well in PWM
> applications, driven by a micro.
> 
> paul perry Melbourne Australia
> ----- Original Message ----- From: "Kyle Stephens" Sent:
> Tuesday, April 20, 2010 11:16 AM
> Subject: Re: [sdiy] Photodarlington Optocouplers
> 
> 
> > Ditto on the H11F3. It's a just like a Vactrol,
> except:
> > 
> > -Smaller footprint, in a standard DIP package
> > -Advertised 99.9% linearity
> > -Response time in uS, versus ms
> > -~100R - ~300M resistance range
> > -And my fav: a lot cheaper!
> 
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