[sdiy] function generators as slave oscillators

[Scott Nordlund]

I just thought about this a little bit more...

Using the function generator's trigger input in "gate" mode (basically similar to oscillator sync) results in an approximately fixed frequency synchronized harmonic of the input signal (more or less what you'd get by syncing a fixed frequency VCO to a variable frequency VCO).

A variant of this can be done with an oscilloscope that has a sweep output, by simply triggering the sweep with an input signal. The result here would actually be an approximately fixed frequency synchronized SUBharmonic. It's a subharmonic because the sweep isn't triggered again until it has completed. I don't know of any typical synth equivalent to this. The funny thing is, aside from using the sweep out directly, you can (very crudely) control the output waveform by attaching an optical sensor to the oscilloscope's display.

I haven't tried this yet, but it might be worth playing around with. I'm sure I can get something really bizarre out of it.

Also, here's the finished result of my previous recording session: http://youtu.be/s0kdF7t9a2U Confusing details are in the video description.

> Date: Sun, 10 Feb 2013 14:18:32 +0100
> From: magnus at rubidium.dyndns.org
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] function generators as slave oscillators
>
> Hi Scott,
>
> On 02/10/2013 09:38 AM, Scott Nordlund wrote:
>>
>> I made a short (and obnoxious sounding) example recording: http://www.mediafire.com/?m8nknxxtl16hnve
>>
>> I'm using two function generators here; a Wavetek 145 and 188. The first part starts with just the Wavetek 145 synchronized in trig (one-shot) mode, which sounds sort of like a variable pulsewidth or filter as I change the frequency. I then switch to gate mode (0:22), which sounds like oscillator sync. Then I modulate the Wavetek 145's VCG input with the Wavetek 188 (0:50), then connect the 145's pulse output to the 188's trigger input (1:10). At this point it's some sort of sync-FM feedback loop. Finally, I activate the sweep on the 188 (1:20). Confused knob twiddling follows.
>>
>> It's pretty neat considering how little I paid for them.
>
> As always, all tricks are good to get that timbre shifts that kinda make
> sense and sounds interesting. It's not new, but we need to recall what
> is possible, as we tend to forget what we can do outside the
> comfort-zone and pre-patched setups.
>
> Cheers,
> Magnus
>
>>> Date: Fri, 8 Feb 2013 00:27:26 +0100
>>> From: magnus at rubidium.dyndns.org
>>> To: synth-diy at dropmix.xs4all.nl
>>> Subject: Re: [sdiy] function generators as slave oscillators
>>>
>>> On 02/07/2013 10:16 PM, Scott Nordlund wrote:
>>>>
>>>> Has anyone tried slaving a standard function generator to a VCO or other audio signal by feeding it into the function generator's trig/gate input? I've found it to be a fantastic source of strangeness if you have a sufficiently fancy function generator. The output waveform isn't constant over pitch, so you get a sort of fixed formant filter effect, and this can be modulated using a sweep generator or VCG input. I look forward to making some weird recordings this weekend. I have two Waveteks that are capable of all sorts of nonsense.
>>>>
>>>> Any thoughts or suggestions?
>>>
>>> My brain hurts. But then I realize that you can do it and it should be
>>> an interesting form of "distorsion" and waveshaping.
>>>
>>> Cheers,
>>> Magnus
>>
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