VCF circuit to run off batteries?

gmeredith · Posted: Tue Aug 15, 2006 7:38 pm Post subject: VCF circuit to run off batteries?

Here I go again, something extra for my freaked out mega Casio SK8!! afro

I want to add a VCF to it. There are 4 separate output lines (for each voice of its 4 note polyphony) that go directly from the processor/ROM, outputting the raw samples, which then feed into a VCA chip.

I was wanting to slip a VCF in between these components. All the VCF circuits I have found so far all run off dual rail + - supplies, not single rail, battery level supplies. The Casio has 2 voltage levels inside: +5V for the logic, and about +10V for the audio. I could use either one of these to power a circuit.

Is there any VCF circuits out there that will run off 5-10V DC single rail? With some sort of ADSR and resonance, and CV in?

In reality, I suspect that I will actually need 4 VCF circuits, one for each voice, so a quad VCF would be nice, but I'll take what I can get at this stage, as I'm still 'loinin Mr. Green

Cheers, Graham

zipzap · Posted: Wed Aug 16, 2006 4:27 am Post subject:

I have some circuits somewhere, see if i can find them. Basically it should be no problem. You definatly want to use the analog 10v supply. First of all it gives you more headroom, secondly most single supply designs i know run between 9-12v, and most important you want to keep that logic supply with the logic.
I´ll have a look, in any case, for single supply designs it´s good to look at guitareffect diy pages. They normaly run on single 9v bateries.

zipzap · Posted: Wed Aug 16, 2006 4:38 am Post subject:

The wasp filter works on single supply i think. And the other schematic is the one i thought of. It´s from this great page with masses of 9v effects. What you´re doing sounds like a really cool idea. maybe you want to add some more effects...
http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html#lofomofo
In case some unsolvable trouble accurs, you can alwys hang a filter after the vcas.

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gmeredith · Posted: Wed Aug 16, 2006 4:35 pm Post subject:

Thanks, zipzap that is a great site! I think I found one that is a good starter - it also has a CV input.

I'm still a bit of a noob - what does the symbol "Vr" stand for in this circuit? and the little isolated schematic that has +9V at the top of it - where does that fit in the circuit?

Cheers, Graham

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Blue Hell · Posted: Wed Aug 16, 2006 5:41 pm Post subject:

gmeredith · Posted: Wed Aug 16, 2006 5:48 pm Post subject:

Ahh, so then the little separate circuit with the +9V at the top is the Vr supply circuit, to which its Vr output line connects to all of the other Vr labelled lines in the big circuit? I think I got it!

Cheers, Graham

Blue Hell · Posted: Wed Aug 16, 2006 5:50 pm Post subject:

Think so

gmeredith · Posted: Wed Aug 16, 2006 6:31 pm Post subject:

Thanks for your help!! I have a TL071 op amp lying around. Would that be suitable for the circuit?

Cheers, Graham

zipzap · Posted: Thu Aug 17, 2006 12:25 am Post subject:

It should.

trevize · Joined: Jul 23, 2006 Posts: 3 Location: Venice (Italy)

i did the pcb of the quick&dirty vcf in eagle cad if you want i can send you the files.

gmeredith · Posted: Thu Aug 17, 2006 6:36 pm Post subject:

Thanks, trevize! My email is:

gmeredith1 at yahoo dot com dot au

Cheers, Graham

zipzap · Posted: Fri Aug 18, 2006 1:30 am Post subject:

I would advise you to send your email in a PM! You know there´s spambots that collect everything on the web that looks like a email adress. I´ve already had burned adresses...

trevize · Joined: Jul 23, 2006 Posts: 3 Location: Venice (Italy)

zipzap is right! edit your post as soon as possible, btw email sent!

gmeredith · Posted: Sun Aug 20, 2006 7:01 pm Post subject:

Thanks, guys, done!! Pesky 'bots!!

Thanks, Trevize, for the PCB layout, that's great!!

Cheers, Graham