temperature sensors
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Hi all,
I am trying to find a temperature sensor
that will measure something between 0 F
and 100 F (greater range is fine)
and can offer an accuracy of better than
one degree F.
Seems the IC's that offer serial outputs
have poor accuracy's and I know that the
thermocouples have way too low of a raw
signal to offer the resolution.
I looked at the temperature coefficient of
a diode (PN junction) and that seems to offer
a useable signal, but it requires a lot of
support chips.
Anybody have any ideas or suggestions ?
Dave
I am trying to find a temperature sensor
that will measure something between 0 F
and 100 F (greater range is fine)
and can offer an accuracy of better than
one degree F.
Seems the IC's that offer serial outputs
have poor accuracy's and I know that the
thermocouples have way too low of a raw
signal to offer the resolution.
I looked at the temperature coefficient of
a diode (PN junction) and that seems to offer
a useable signal, but it requires a lot of
support chips.
Anybody have any ideas or suggestions ?
Dave
Comments
accuracy and at least the sort of range you are looking for ...from memeory
try www.ibutton.com
HTH
Mick
Dave Mucha <davemucha@j...> said:
> Hi all,
>
> I am trying to find a temperature sensor
> that will measure something between 0 F
> and 100 F (greater range is fine)
> and can offer an accuracy of better than
> one degree F.
>
> Seems the IC's that offer serial outputs
> have poor accuracy's and I know that the
> thermocouples have way too low of a raw
> signal to offer the resolution.
>
> I looked at the temperature coefficient of
> a diode (PN junction) and that seems to offer
> a useable signal, but it requires a lot of
> support chips.
>
> Anybody have any ideas or suggestions ?
>
>
> Dave
>
>
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--
The best grade of LM34CAH or LM34CAZ (analog 10mv/degree) assure
accuracy off the shelf to +/- 1 degree F.
The DS1620 (spi interface) is accurate to +/- 0.5 deg. C over range
of the 0 to 70 degees C.
-- best regards
Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com
mailto:tracy@e...
>Hi all,
>
>I am trying to find a temperature sensor
>that will measure something between 0 F
>and 100 F (greater range is fine)
>and can offer an accuracy of better than
>one degree F.
>
>Seems the IC's that offer serial outputs
>have poor accuracy's and I know that the
>thermocouples have way too low of a raw
>signal to offer the resolution.
>
>I looked at the temperature coefficient of
>a diode (PN junction) and that seems to offer
>a useable signal, but it requires a lot of
>support chips.
>
>Anybody have any ideas or suggestions ?
>
>Dave
resolution, and accuracy, you need.
Isn't the DS1620 acurate to 1/2 deg C? (don't have the data handy,
sorry)
Rich
--- In basicstamps@y..., "Dave Mucha" <davemucha@j...> wrote:
> Hi all,
>
> I am trying to find a temperature sensor
> that will measure something between 0 F
> and 100 F (greater range is fine)
> and can offer an accuracy of better than
> one degree F.
>
> Seems the IC's that offer serial outputs
> have poor accuracy's and I know that the
> thermocouples have way too low of a raw
> signal to offer the resolution.
>
> I looked at the temperature coefficient of
> a diode (PN junction) and that seems to offer
> a useable signal, but it requires a lot of
> support chips.
>
> Anybody have any ideas or suggestions ?
>
>
> Dave
At about 100 degrees F. the LM34 puts out a raw count of about 850 which
converted to millivolts is about 1010. The highest count you can get with 8
bits is 255. I use 12 bits to get the full count.
Enlighten me, please.
Sid - W4EKQ
Just went through a similar search. Your +/- 1[noparse][[/noparse]°F] is a bit tough,
but Maxim/Dallas Semiconductor DS18B20 are accurate to +/- 0.5[noparse][[/noparse]°C]
over the middle of the range and give 12bit resolution (0.0625[noparse][[/noparse]°C])
by default. The BS2P talks with these quite easily with just a couple
of statements. The advantage to these 1 Wire devices is they are
addressable and can have many on just one i/o line.
If you are interested in more resolution and a simpler interface
check out MAXIM MAX6577ZUT Temperature sensor with frequency output.
These can be directly connected to a stamp I/O pin without need for
an ADC. I haven't received the samples I ordered yet, but I
calculated a maximum resolution of 0.000416[noparse][[/noparse]°C] @ 70[noparse][[/noparse]°C] (my temp.
range of interest) using a BS2P and the PULSIN command.
Stated accuracy is +/-0.8[noparse][[/noparse]°C] @ room temp and goes down to +/-0.5 at
higher temperatures. Of course accuracy of the stamp clock will come
into play as well.
Happy Stamping,
Dean
--- In basicstamps@y..., "Dave Mucha" <davemucha@j...> wrote:
> Hi all,
>
> I am trying to find a temperature sensor
> that will measure something between 0 F
> and 100 F (greater range is fine)
> and can offer an accuracy of better than
> one degree F.
>
> Seems the IC's that offer serial outputs
> have poor accuracy's and I know that the
> thermocouples have way too low of a raw
> signal to offer the resolution.
>
> I looked at the temperature coefficient of
> a diode (PN junction) and that seems to offer
> a useable signal, but it requires a lot of
> support chips.
>
> Anybody have any ideas or suggestions ?
>
>
> Dave
Thanks,
Seems the temperature market is strewn with options.
Thermocouples offer very high temperatures,
but bad resolution (in my range)
RTD's offer good resolution, but are expensive ($10.00 range)
A PN junction offers good resolution, low price,
but requires a lot of support chips and needs to be field calibrated.
Thermistors offer good resolution,
but are expensive and by my findings, they drift.
I like the idea of the 1 Wire from Dallas.
I think we will put up a web page of the findings as we get some
empirical data on the comparisons of these chips and sensors.
Dave
--- In basicstamps@y..., Dean_Severns@W... wrote:
> Dave,
>
> Just went through a similar search. Your +/- 1[noparse][[/noparse]°F] is a bit tough,
> but Maxim/Dallas Semiconductor DS18B20 are accurate to +/- 0.5[noparse][[/noparse]°C]
> over the middle of the range and give 12bit resolution (0.0625[noparse][[/noparse]°C])
> by default. The BS2P talks with these quite easily with just a
couple
> of statements. The advantage to these 1 Wire devices is they are
> addressable and can have many on just one i/o line.
>
> If you are interested in more resolution and a simpler interface
> check out MAXIM MAX6577ZUT Temperature sensor with frequency output.
> These can be directly connected to a stamp I/O pin without need for
> an ADC. I haven't received the samples I ordered yet, but I
> calculated a maximum resolution of 0.000416[noparse][[/noparse]°C] @ 70[noparse][[/noparse]°C] (my temp.
> range of interest) using a BS2P and the PULSIN command.
> Stated accuracy is +/-0.8[noparse][[/noparse]°C] @ room temp and goes down to +/-0.5
at
> higher temperatures. Of course accuracy of the stamp clock will
come
> into play as well.
>
> Happy Stamping,
> Dean
>
> --- In basicstamps@y..., "Dave Mucha" <davemucha@j...> wrote:
> > Hi all,
> >
> > I am trying to find a temperature sensor
> > that will measure something between 0 F
> > and 100 F (greater range is fine)
> > and can offer an accuracy of better than
> > one degree F.
> >
> > Seems the IC's that offer serial outputs
> > have poor accuracy's and I know that the
> > thermocouples have way too low of a raw
> > signal to offer the resolution.
> >
> > I looked at the temperature coefficient of
> > a diode (PN junction) and that seems to offer
> > a useable signal, but it requires a lot of
> > support chips.
> >
> > Anybody have any ideas or suggestions ?
> >
> >
> > Dave