> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of IVP
> Sent: 13 June 2012 11:44
> To: Microcontroller discussion list - Public.
> Subject: [PIC] RC oscillator calculation
>=20
> Hi all,
>=20
> I've got a PIC project with a speed control that is a pot as the R in RC =
mode
>=20
> One option I would like is to be able to set a mid-point frequency such t=
hat
> moving the pot fully counter-clockwise will be the same ratio as slow as =
fully
> clockwise is as fast
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> The equation would be x * (1/y) < x > x * y
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> For example, in the range 2 to 32, 8 (=3Dx) is the 'midpoint' and y =3D 4
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> 2 is 8 * 1/4 and 32 is 8 * 4
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> How would I (can I) resolve the equation to find 'x', the midpoint, if I =
have
> just the range, which in this case is 500kHz to 4100kHz ?
>=20
> I can guess at say 1400kHz. 1400/500 =3D 2.8. 2.8 * 1400 =3D 3920, which =
is close
> but there must be a better way
>=20

SQRT(500kHz * 4100kHz) =3D 1431.78kHz

Cheers

Mike


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