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

[Ake Hedman <akhe@xxxxxxxxxxxxx>]

Nick,

+12V will be fine. Just choose the resistor so it is within the range of=20
the device (400uA - 5mA(. Lift the ground with a forward biased diode.=20
That way go get an offset from zero and can measure negative=20
temperatures and feed the output to a non inverting op-amp=20
stage(http://www.play-hookey.com/analog/non-inverting_amplifier.html)
.

Cheers
/Ake

Nick wrote:

>
> I have finally acquired my LM335 temperature sensor.  I have done
> some studying of the datasheet (see
> http://www.maplin.co.uk/Media/product_pdfs/YY73.pdf)=20
> <http://www.maplin.co.uk/Media/product_pdfs/YY73.pdf%29>
and I have read
> through the advice previously given here.
>
> What I need to do is persuade it to give me a steeper voltage curve
> than the default 10mV/degree.  I also need to offset its output to
> get usable voltages for the range of temperatures expected in the
> UK. It seems that what I need to do is persuade an OpAmp to give me
> an offset and provide some amplification.  The absolute ideal would
> be:
>
> 12 volt supply (so I can take it from Comfort - although I could
> always add a 5v regulator I guess).
>
> x10 amplification to give me 100mV/degree.
>
> An offset so that 0v is at -10 degrees and 5v is at +40 degrees.
>
> That would give a feed to Comfort varying between 0 and 5v (over the
> 50 degree range from -10 to +40) which is what is expected.
>
> What I need is some simple guidance on how to construct such an
> animal using an op-amp (presumably 741 or similar).
>
> All pointers and help welcome,
>
> Nick
>
>
>
>
>
>
>
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--=20
---
Ake Hedman (YAP - Yet Another Programmer)
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