DIY Function Generator = Possible Wierdness for Pedals?

[erix]

The DIY-ness in me wants to build a function generator for testing audio and effects projects. I've been looking at various kits and one that looks really easy to make relies on a single IC - the Exar XR-2206.

This handy-looking chip can run on single or dual supplies and can output a sine, triangle, and square wave from 1Hz to over 1MHz!

XR-2206 link --> http://www.exar.com/product.php?ProdNumber=XR2206&areaID=
XR-2206 Datasheet --> http://www.exar.com/products/XR2206v103.pdf

The Exar site even has an app note on how to build such a beast: http://www.exar.com/products/tan005.pdf

So, whilst laying it out I began to wonder - could not this chip be a functional VCO or other wave-generating functional block in some sort of wierdo-filter effect? Note the amplitude modulation and Frequency Sweep inputs.

I plan on housing it in a 1590B, with banana and BNC jacks for Square, Pulse, Sine/Triangle outputs as well as Ground and Amplitude Modulation and sweep inputs. I figure it's better to put them all on there and figure out a use for them later!

Has anyone built their own frequency genrators? I'm aware of RG's simple-sine one and basic opamp square-wave ones, but has anybody experimented with these purpose-built chips?

ok,
erix

[ErikMiller]

http://www.euthymia.org/DIY/Eriksosc.jpg

I have mine set up to just supply a sine wave, but it can do squares and triangles with a bit more effort.

Although I now have multiple bench function generators, I have this one built into a small plastic box, and still use it often as a battery-powered portable.

[john-mike]

I've played with that chip ALOT
It's the primary chip in thingamableeps I sell at www.bleeplabs.com

The FSK input is probably the best it could do as an effect. Waveform gen is done just as well by a single supply opamp since
Sine isn't reeeealy necessary for lfos.

[Zero the hero]

I used this one in my BlueBoob ring modulator. This chip is powerful!!!!
I feeded pin 7 with a LFO for frequency sweeping (and more).

[Processaurus]

I've got a couple of those kicking around,  I'm thinking about using one to produce a sine wave to make a vibrato on my small clone clone sound better, the triangle lfo doesn't cut it because the pitch shifts directions too abruptly.  Its gotta be smoooth.  I've been a little put off using it because the data sheet says it needs at least 10v to power it, but I'll try it on 9v since it looks like other people are. 

Another LFO idea: If you full wave rectified the sine wave, you'd have a nice hypertriangular lfo for flangers and phasers. 

The PLL capabilities of the chip are really interesting, I wonder how well it would work to use one in an octave divider, to use the triangle or sine outputs for a different sound than the filtered square wave sub octave you usually see being used.

[didier]

i was planning on using it a while ago in an effect.

well, i also did but i couldnt get it to work for some reason... maybe i'll pick it up later...

i'll try to post my schematic soon too so you can have a look
also some more info...