[sdiy] 555 VCO (was : <no subject>)

[patchell]

>
> I'm not sure, but I think it's pretty hard to find a good
> "VCO chip" these days.  The AD654 would be good if I could just
> get my hands on one, but these things and others like it, have
> gone the way of the dodo bird.  You really have to resolve
> yourself to putting one together with other parts such as opamps,
> OTAs, transistors etc.  Many people on this list have posted
> schematics for a good variety of VCO designs or various complexity
> and performance.
>

    For VCO's that might be considered to be a bit on the complex side, check out
my web site below.

    Ian Fritz has done a lot of experimenting with VCO's.  His website is at
http://home.earthlink.net/~ijfritz/index.htm.

    Personally, I would stay away from the 555 myself (sorry, I am a 555 bigot).
Something like a good old fashsioned comparator, like the LM311 or LM319 (I
prefer the 311, since there is only one of them in the package), work out much
better in the long run.  If you build something like the ASM1 VCO, it is hard to
get much simpler than that.  Basically, it consists of four opamps, a comparator,
a fet, and a dual transistor.

>
> >Check out these websites:
> >
> >http://www3.ncsu.edu/ECE480/images/aa-555-01.gif
> >http://www.andy-clarkson.co.uk/555/
> >
>

--
 -Jim
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