Other alternatives...

Linear Technology and Maxim have both introduced stable RC
oscillator IC's. Linear Tech's sets the frequency via resistor
value. Maxim's uses an internal preset RC frequency and has a
programmable divider (via a 2 or 3 wire interface) that allows
you to program a specific output frequency. They have several
models with different base frequencies.

Data is available for both parts on their web sites.

Matt Pobursky
Maximum Performance Systems

On Mon, 11 Mar 2002 10:31:32 -0800, Michael Vinson wrote:
>Hi list! I have a question. I need a variable-frequency square-
>wave timing signal in the range 3-5MHz. For slower applications,
>I usually wire up a 555 in astable mode with a pot to control
>the period (and maybe another to control the duty cycle, if need
>be). But I can't seem to get the 555 to go fast enough for my
>current project.
>I've been using a 4MHz crystal oscillator, but now discover I
>need to vary the frequency +/- 1MHz (with 50% duty cycle or so:
>it isn't critical). It would be great to be able to vary the
>frequency continuously with a pot. Any suggestions? Thanks in
>advance!
>
>Michael V
>

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