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From: johnydep on 24 Nov 2009 08:05
We are using Fuel sensor of Capacitence level transmitter which takes input
24 volts and gives output as 4-20 ma. When I am converting 4 ma to 20 ma
using 250 resistor, converting into voltages.

We are getting 10 values 4 ma to 5 ma ex: 4.1,4.2,4.3 etc..,

When we are converting to voltages and taking adc values, adc values are
rapidly changing. I am unable to note the adc values.

Please help me from this problem.



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From: linnix on 24 Nov 2009 11:01
On Nov 24, 5:05 am, "johnydep" <janashr...(a)gmail.com> wrote:
> We are using Fuel sensor of Capacitence level transmitter which takes input
> 24 volts and gives output as 4-20 ma. When I am converting 4 ma to 20 ma
> using 250 resistor, converting into voltages.
>
> We are getting 10 values 4 ma to 5 ma ex: 4.1,4.2,4.3 etc..,
>
> When we are converting to voltages and taking adc values, adc values are
> rapidly changing. I am unable to note the adc values.
>
> Please help me from this problem.
>
> ---------------------------------------        
> This message was sent using the comp.arch.embedded web interface onhttp://www.EmbeddedRelated.com

Google on op-amp amp/buffer or hire someone who knows electronics.
From: RockyG on 24 Nov 2009 12:26
>On Nov 24, 5:05=A0am, "johnydep" <janashr...(a)gmail.com> wrote:
>> We are using Fuel sensor of Capacitence level transmitter which takes
inp=
<Snip>
>> Please help me from this problem.
>>
>
>Google on op-amp amp/buffer or hire someone who knows electronics.
>
Decaf Linnnix, Decaf!

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From: WangoTango on 24 Nov 2009 16:23
In article <6MKdnUTr2oq3R5bWnZ2dnUVZ_qmdnZ2d(a)giganews.com>,
janashriya(a)gmail.com says...
> We are using Fuel sensor of Capacitence level transmitter which takes input
> 24 volts and gives output as 4-20 ma. When I am converting 4 ma to 20 ma
> using 250 resistor, converting into voltages.
>
> We are getting 10 values 4 ma to 5 ma ex: 4.1,4.2,4.3 etc..,
>
> When we are converting to voltages and taking adc values, adc values are
> rapidly changing. I am unable to note the adc values.
>
> Please help me from this problem.

Keep a circular queue of N number of samples and then average them?

From: Meindert Sprang on 25 Nov 2009 03:36
"WangoTango" <Asgard24(a)mindspring.com> wrote in message
news:MPG.257618e3facbc9ed98ad2c(a)news.east.earthlink.net...
> In article <6MKdnUTr2oq3R5bWnZ2dnUVZ_qmdnZ2d(a)giganews.com>,
> janashriya(a)gmail.com says...
> > We are using Fuel sensor of Capacitence level transmitter which takes
input
> > 24 volts and gives output as 4-20 ma. When I am converting 4 ma to 20 ma
> > using 250 resistor, converting into voltages.
> >
> > We are getting 10 values 4 ma to 5 ma ex: 4.1,4.2,4.3 etc..,
> >
> > When we are converting to voltages and taking adc values, adc values are
> > rapidly changing. I am unable to note the adc values.
> >
> > Please help me from this problem.
>
> Keep a circular queue of N number of samples and then average them?

Or use only 4 MSB's of the ADC result...
Oh, and a large capacitor (100uF) across the 250 ohm resistor to get rid of
any noise.

Meindert



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