> I've got a variable frequency signal (200hz to 4khz) whose frequency I
> want to increase by 30% (5v signal).  IE if the input frequency is
> 1000hz, I want to output 1300hz.  Is there an easy method of doing
> this?  I've heard of PLL, but don't have a clue how to build them, so
> if there's an easier option that would be great.

A PLL (Phase Locked Loop) could be a solution.  If you don't have a clue
about them, then learn or get someone else to do the design.  There's got
to be loads of material out there on PLLs, so I won't repeat most of it
here.  Basically, you can use a PLL to multiply a frequency by a rational
number.  However, things get more tricky as the integers get larger and
the frequency range ratio gets wider.

Depending on response speed, a PIC might be another solution.  You could
use a CCP module in capture mode to determine the incoming period, then
use PWM output to produce a signal with .77 of the input period.


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