Re: LM35 - Length of cable ?

["Mark Marooth" <MMarooth@xxxxxxx>]

Hi Frank,

Runs should be no longer than 20 feet through the roof space.  You've
also
confirmed what I suspected about noise, as I am running thorugh roof
space,
think I'll use something shielded.


Mark



--------+------------------------>
       
          "Frank
Mc     
       
         
Alinden"      
       
         
<armagh@xxxxxxx
       
         
d.com>        
       
                       
       
         
31/05/2002    
       
         
12:09         
       
          Please respond
       
          to
ukha_d     
       
                       
--------+------------------------>
 
>----------------------------------------------------------------------------
 
                                                                           
        To:    
ukha_d@xxxxxxx                                       
        cc:     (bcc:
Mark
Marooth/SCOTIA)                                   
        Subject:     Re:
[ukha_d] LM35 - Length of cable
?                   
 
>----------------------------------------------------------------------------




Hi Mark
               
Havnt used the analogue sensor . The capacitance shouldnt be
a problem with unshielded cable but not being shielded you may get
noise
injected into your analogue signal, so keep the cables well away from
mains
type stuff . How long are your runs?
Frank Mc
----- Original Message -----
From: "Mark Marooth" <MMarooth@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Friday, May 31, 2002 8:58 PM
Subject: [ukha_d] LM35 - Length of cable ?


>
>
> Chaps,
>
>
> I'm going to be building a couple of temperature sensors this weeked
using
the
> LM35D IC hooking into me Weeder Analogue In card.  I'm not too
sure how
long a
> cable I can run before the IC gives up the ghost as far as load is
concerned.
> Thought I'd use 3/4 core alarm wire providing power (12V) and a return
for
the
> sensor values.
>
> The specs say it will drive upto 50pf without special precautions but
I'm
afraid
> my electronics maths is not that good to turn that into cable
length
and/or
> load.
>
> Does anyone have experience of this chip and cable length.  If
load is a
problem
> then I can decouple with either a resistor (2k) or with an R-C
damper.
>
>
> Any thoughts,
>
> TIA
>
>
>
> Mark
>
>
>
>
> For more information: http://www.automatedhome.co.uk
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>



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