[sdiy] Possible New Waveform Generator Circuits

[Scott Gravenhorst]

"Steven J" <g546 at mailbox.co.za> wrote:
>On Tue, 6 Apr 2004 21:48:54 -0500
> David Cornutt <cornutt at hiwaay.net> wrote:
>> 
>> On Tuesday, April 6, 2004, at 08:26  PM, Peter Snow
>> wrote:
>> 
>> > About spiral waveforms - if they do indeed exist, you
>> would think that 
>> > someone would have come up
>> > with a circuit before now...
>> >
>
>-I said the same thing in my original post.
>
>> then you could visualize a
>> spiral as
>> a sine wave that gradually increases or decreases in
>> amplitude
>> and frequency.
>
>Yes, that is another way of describing spiral waveforms.
>
>> However, there's certainly nothing radical about that;
>> anyone on
>> this list could create one easily.
>
>How?

One simple way:
2 sine wave oscillators, same frequency, 90 degrees out of
phase (or one quadrature sine wave oscillator), with outputs
passed thru a dual VCA driven by a sawtooth oscillator,
possibly synched to one of the sine oscillators.  The
modulation waveform could be others besides sawtooth, but
sawtooth will present a spiral on an X-Y driven scope if
connected to the VCA outputs.


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