Re: Re: Op-Amp ----- any experts around this afternoon?

[Ake Hedman <akhe@xxxxxxxxxxxxx>]

Nick,

This problem stuck in my head.

If you want a perfect translation between the LM335 output in any region=20
and translate it to 0-5V you could use a PIC12F675 and read the LM335=20
output with its A/D converter, scale it to your needs and output it as=20
PWM on one output pin in the region 0-5V. Oh well,  just a thought I had=20
to share.....

Cheers
/Ake

Nick wrote:

>
> > just a  correction. There is no need
> > for the diode as the ouput is in
> > Kelvin. Subtract 2.73 from the reading
> > and you get Celsius. Sorry for that.
> >
> > /Ake
>
> Ake, I must be getting there because I was just about to ask why I
> needed the diode!  You beat me to it with your second post.
>
> Thanks for the link.  That shows three resistors which if I am
> calculating correctly, should be:
>
> Rf =3D 20k
> Rin =3D 2.2k
>
> to get the gain of ten (Equally I guess I could use 200k and 22k,
> and I'm not sure how to choose).  Then:
>
> Rz =3D 0.5k
>
> as it suggests a value "equal to the parallel combination of Rf
and
> Rin" which, if I remember rightly is the sum of the reciprocals.
>
> How am I doing so far?  If I am understanding ok so far, then I
> think I have the gain aspect sorted, giving me 1 volt per 10 degrees.
>
> I am not sure how to achieve the "offset" so that the 0-5v
values
> that Comfort expects are at a sensible place within the device's
> spectrum.  In other words, what I have so far, I think, will still
> give 0v at 0 degrees kelvin and 5v at +50 degrees Kelvin.
>
> What I need is 0v at -10 degrees Centigrade and 5v at +40 degrees
> Centigrade.
>
> Hope that makes sense.  Thanks again,
>
> Nick
>
> PS, once I get this sorted, I'll publish the results as it sounds
> like a very cheap way of getting temperatures into Comfort (etc).
>
>
>
>
>
>
>
>
>
> *Yahoo! Groups Sponsor*
> ADVERTISEMENT
> click here=20
> <http://us.ard.yahoo.com/SIG=3D129ftb3mq/M=3D298184.6191685.7192823.30011=
76/D=3Dgroups/S=3D1705041992:HM/EXP=3D1112031515/A=3D2593423/R=3D0/SIG=3D11=
el9gslf/*http://www.netflix.com/Default?mqso=3D60190075>=20
>
>
>
>
------------------------------------------------------------------------
> *Yahoo! Groups Links*
>
>     * To visit your group on the web, go to:
>       http://groups.yahoo.com/group/ukha_d/
>=20=20=20=20=20=20=20=20
>     * To unsubscribe from this group, send an email to:
>       ukha_d-unsubscribe@xxxxxxx
>       <mailto:ukha_d-unsubscribe@xxxxxxx?subject=3DUnsubscribe>
>=20=20=20=20=20=20=20=20
>     * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
>       Service <http://docs.yahoo.com/info/terms/>.
>
>


--=20
---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergav=E4gen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se=20=20=20=20=20=20
Kryddor/Te/Kaffe: http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe
Automated home: http://www.vscp.org



[Non-text portions of this message have been removed]