[sdiy] "Load" on power supply changes pitch of VCO...

[Paul Perry]

Those regulators should be able to do a good job
with only .01 on the output, I would agree with the
observations that 12 or 12.5 AC just isn't enough.
I use 15V regs in most of my gear & anything under
14V AC input is a problem.
The fact that increasing the output regs tenfold
decreases the buzz, shows that they are acting more like
dropping resistors than regulators.

paul perry Melbourne aaustralia

----- Original Message ----- 
From: "Mike Beauchamp" <mikebeauchamp at gmail.com>
To: "tony Rolando" <goldenechos at hotmail.com>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, February 22, 2007 7:00 PM
Subject: Re: [sdiy] "Load" on power supply changes pitch of VCO...


> Actually, I poked around more with my circuit.. and I noticed the
> capacitors I had on the output of the voltage regulators were .01uF
> and the datasheets call for .1uF for "increased stability and
> transient response". So I swapped them out just to check, and it seems
> like the voltage isn't dropping anymore and the regulators are
> actually regulating. Not only that, but this odd buzz I was getting on
> the very high frequencies is now gone and the output is
> cleaaaaaaannnn.
>
> I'm gonna go downstairs and run more tests to be sure that's the
> problem solver.. but either way, thanks for all the repsonses thus
> far.
>
> Mike
>
>
> On 2/22/07, tony Rolando <goldenechos at hotmail.com> wrote:
> > Tried a 15VAC supply?
> >
> > TR
> >
> >
> > >From: "Mike Beauchamp" <mikebeauchamp at gmail.com>
> > >To: synth-diy at dropmix.xs4all.nl
> > >Subject: [sdiy] "Load" on power supply changes pitch of VCO...
> > >Date: Thu, 22 Feb 2007 01:07:45 -0500
> > >
> > >Paul Perry> If it helps, the powersupply I made for the XR-2206 VCO is
> > >a 12VAC wallwart that gets rectified, filtered with .1uf caps and
> > >470uF caps and fed into  7815 and 7915 voltage regulators to give me
> > >+15 and -15V.
> > >
> > >My VCO is "stable" in that it doesn't drift, however the frequency
> > >changes if I add more load (like an led or something) to the power
> > >supply.
> > >
> > >Maybe I'm wrong assuming that using power from voltage regulator chips
> > >gives me a "regulated power supply"?
> > >
> > >Mike
> > >
> > >On 2/21/07, Paul Perry <pfperry at melbpc.org.au> wrote:
> > >>If you want a stable VCO using an XR-2206, then you need a
> > >>regulated power supply.
> > >>
> > >>paul perry Melbourne Australia
> > >>
> > >>----- Original Message -----
> > >>From: "Mike Beauchamp"
> > >> > The first VCO I built was Thomas Henry's XR-2206 VCO
> > >> > (http://mypeoplepc.com/members/scottnoanh/birthofasynth/id20.html).
> > >> >
> > >> > I'm noticing that when I experiment and add various things, the
pitch
> > >> > changes. It's as though the pitch is dependent on how much current
I'm
> > >> > drawing from the power supply.
> > >> >
> > >>
> > >>
> > >
> > >
> > >--
> > >Mike Beauchamp
> > >Cross Canada Project: http://mikebeauchamp.com/crosscanada
> > >Personal: http://mikebeauchamp.com
> > >Business: http://therevox.com
> > >Windsor News: http://windsorinb.relyon.ca
> > >
> > >
> > >--
> > >Mike Beauchamp
> > >Cross Canada Project: http://mikebeauchamp.com/crosscanada
> > >Personal: http://mikebeauchamp.com
> > >Business: http://therevox.com
> > >Windsor News: http://windsorinb.relyon.ca
> >
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>
> -- 
> Mike Beauchamp
> Cross Canada Project: http://mikebeauchamp.com/crosscanada
> Personal: http://mikebeauchamp.com
> Business: http://therevox.com
> Windsor News: http://windsorinb.relyon.ca
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>
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