[sdiy] Hewlett oscillator

[Dave Leith]

Re: Wien bribge

I believe that circuit looks like the oscillator that's used in the
Maestro Ring modular. I replaced the 2 R's with a dual vactrol to get
a basic voltage control (almost linear :-) of the circuit - it's kinda
nice.

On Fri, Nov 28, 2008 at 11:46 AM, Aaron Lanterman
<lanterma at ece.gatech.edu> wrote:
>
> On Nov 27, 2008, at 4:42 PM, Grant Richter wrote:
>
>> For an onboard sine source, your best bet would be a single op-amp Hewlett
>> design with an incandescent lamp for soft limiting.
>> Both the ICL8038 and XR2206 have sine waves with a THDs of 5%, this is not
>> good.
>> The Hewlett design should have a THD of less than 1%, much better.
>> This sine wave can be normalized to the SIGIN jack, then if you need
>> voltage control of the carrier frequency, you can patch it externally.
>>
>> The on-board sine source can then be a simple potentiometer control. A
>> suggested range is 10 Hz to 1kHz.
>> Adding a wider range is not musically useful, at a 1kHz carrier frequency
>> everything is shifted so high it's almost inaudible.
>> Th simple sine source should have a panel output also with a 1K resistor
>> in series.
>
> Some Wiki foo brings me this:
> http://en.wikipedia.org/wiki/Wien_bridge_oscillator
>
> The design I see there has two Rs, so I guess I'd need a ganged pot? Or is
> there a way to work around it to use only a single pot?
>
> - Aaron
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