XR2206 question

[rubendelacosta]

hi
just found out about this i.c.
http://www.bls.fr/amatech/electronique/radio/Modem_300/xr2206.pdf

and it looks like a ready to go VCO... I'm I right?
on the datasheet circuit examples there's one thing that i can't understand...what is "FSK IN"?

any simple vco schematic?i don't mind if it's not 1v/oct

[bugbrand]

Yes - a very good chip!

Two examples, both from the great Thomas Henry:::

XR VCO via Scott Stites' web
- top-freaking-notch!

And The VCO Chip Cookbook via sMs electronics
- hmm, the thread in the TH forum seems to have vanished??!! Maybe the printing sold out for now?? Anyways, ask Bill StateMachine.
Totally essential reading, no doubt about it!

[yusynth]

There ought to be a sticky FAQ thread somewhere, because topics like
"I have just discovered the XR2206 ( or 555 or 8038...) and is it good for a VCO" are more than recurring !

[Appliancide*]

A chip questions thread would be a great idea. I know that recently I've found some chips that I needed being sold with a bunch of other chips that I have no idea what they do, so it would be great to able to have one place to look and then ask if anyone knows of a good application for it. Maybe the top post could be a list of chips and circuits they are used in.

[BOB-SNARE]

I'm trying to implement hard sync (not the TH way) on a XR2206 VCO.
I've tried shorting out the cap (using a 4066 analog switch)
and the problem seems to be that the cycle is reset to either 0 or 180deg
depending on what state the integrator is in before shorting the cap.

Should I use FSKI and switch in a small cap and 1k resistor to GND
on pin 8 and use the SYNCO output to control cap shorting switch,
so that the syncing is always done when the integrator is in a known state?

Or is there a simpler way?

btw my sync pulse is 4us.


A slightly related question. Does the 8038 have the same problem with syncing?

Cheers