[sdiy] low voltage filters

[Declare Update]

Howdy list,

Just following up on this discussion! LM13700 SVF, very similar design to Electronotes, Oberheim, Thomas Henry, etc, works on a single supply down to 3.3V. Lower even, but I didn't bother checking past 2.7ish. Very happy :) 

Cheers,
Chris 



Sent from my iPhone

> On Apr 27, 2017, at 6:38 PM, Lindsay <l.campbell3220 at yahoo.co.uk> wrote:
> 
> A bit wasteful prehaps (unless you can find a use for the rms detectors), and only in smd  (/ dip via adapter) but the THAT4316 has a VCA, operates down to 2.7V and is cheap enough.   Check out design note 130, adapt and cascade sections for 2nd order.  I'm working on something similar using the 4315 (spec'd to 4.5V) for a 9V guitar envelope filter - spice reckons it'll work!  The 4316 works a little differently than the other 43xx ics- the vca out is non inverting, mV/dB constant is reduced, extra filtering required at vca in...cv tracking is not a big concern for my application but it's current in/out so shouldn't be too dirty.  also mouser have them.
> 
> Linds
> 
> 
> 
> 
> Sent from my iPad
>> On 19 Apr 2017, at 20:38, Chris McDowell <declareupdate at gmail.com> wrote:
>> 
>> Howdy list! 
>> 
>> Wondering if anyone is aware of, or has any tips towards, some low voltage VCF designs. I've seen reports of people using LM13700s with a single 5V supply for VCAs, and their one-off forum posts made them seem happy, heh. I realize this would have very little headroom. I've also checked out Hoshuyama's site, which has a few battery-powered designs. Some things I've considered: 
>> 
>> - Perhaps LM13700 just works at 5V ¯\_(ツ)_/¯ (avoiding breadboard as long as possible…)
>> - Discrete OTA with BJTs
>> - MS-20 Style, like the monotron 
>> - Vactrol, H11F1, or similar 
>> 
>> The point of this is that I have DCOs and ADSRs working wonderfully in a 3.3V environment. Some dirt is okay, I say. Super ideally, I want to implement an SVF with a single 3.3V supply, suggestions toward reality / sacrifices are welcome. I imagine this would work fine with vactrols, but I don't want to design anything with parts I can't buy from mouser, hehe. 
>> 
>> Cheers, 
>> Chris 
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