Reading RTD''s
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Posts: 46,084
hi phill.
could you send a copy of the schematic for the thermocouple system?
normdoty@b...
id like to see if i can help with the interference problem.
thanks
>From: "Phillip Kocmoud" <pkocmoud@h...>
>Reply-To: basicstamps@yahoogroups.com
>To: <basicstamps@yahoogroups.com>
>Subject: RE: [noparse][[/noparse]basicstamps] Re: Reading RTD's
>Date: Tue, 28 Jan 2003 11:53:01 -0600
>
>The problem with interference arouse from using Analog Devices AD595. This
>is supposed to read the thermocouple, Condition it, linearize, and
>Compensate for the cold junction, then output 10mv per degree Celsius. The
>whole thing works great in my workshop, but I take it onsite and I get a
>odd
>spiking signal. It shows fluctuations up and down of 500 or more degrees.
>It
>almost looks like it has a heart beat... The only thing that is different
>is
>the location. I am running it a max length of 75 feet. With experimentation
>I have found the interference occurs when I extend the length beyond 10
>feet. I am also using K type thermocouples with K type thermocouple
>extensions. I have also tried tyroid coils, capacitors, and resistors. The
>capacitors and resisters helped, but changed the linearity of the output
>from the chip. It need to be accurate to about 1 degree Celcius or less, as
>stipulated be the government!
>
>
Original Message
>From: Dave Mucha <davemucha@j...> [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=f7YAXStYgetI4YFp6LebL7QjdUauvFs_rxvWQHKwC1lYkE7WPtLbE9lumwGOFxH8j3pQwSYn2UBo]davemucha@j...[/url
>Sent: Sunday, January 26, 2003 11:12 PM
>To: basicstamps@yahoogroups.com
>Subject: [noparse][[/noparse]basicstamps] Re: Reading RTD's
>
>
>I'm not sure of the reference to the distance of the run and the
>airport interference.
>
>Thermocouples work on a simple bi-metal principal the asserts that
>dissimilar metals joined will product a voltage that varies with
>temperature. the voltage is low, very low.
>
>Understand that dis-similar metals is the key phrase. copper, lead,
>tin, AND the stuff your thermocouple is made of are all dissimilar.
>That means ANY and EVERY junction can act as a sensing point. the
>terminals on your device may be a reference joint. you cannot use
>any extention of thermocouple wire, it MUST be an uninterupted home
>run all the way from the process to your ADC.
>
>errors can be eleminated by a cold junction reference and calibration.
>Curcuit board temperature monitoring also helps to reduce errors.
>
>You might conssidder an automobile exhause gas sensor as well and an
>RTD.
>
>If you get a transmitter, you will gain a complete circuit and have a
>voltage or current output.
>
>Also, you may need to look at thermowell's. these are the metal
>deviced used to house the sensor to the actual sensor does not come
>in contact to the gasses.
>
>Dave
>
>
>
>
>
>
>
>
>--- In basicstamps@yahoogroups.com, "Phillip Kocmoud" <pkocmoud@h...>
>wrote:
> > Can anyone kick me in the right direction? I am interested in
>monitoring the
> > temperature of an industrial oven. The monitored temperature is
>between 0
> > degrees Celsius and 100 degrees Celsius. I have attempted to use
> > thermocouples, but the distance of the run and its location is very
>close to
> > a major airport, I cannot dampen the interference. I think RTD's
>will fill
> > my bill, but I am unable to find practical information for
>integrating them.
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
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>
>
>
>
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> basicstamps-unsubscribe@yahoogroups.com
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>Body of the message will be ignored.
>
>
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could you send a copy of the schematic for the thermocouple system?
normdoty@b...
id like to see if i can help with the interference problem.
thanks
>From: "Phillip Kocmoud" <pkocmoud@h...>
>Reply-To: basicstamps@yahoogroups.com
>To: <basicstamps@yahoogroups.com>
>Subject: RE: [noparse][[/noparse]basicstamps] Re: Reading RTD's
>Date: Tue, 28 Jan 2003 11:53:01 -0600
>
>The problem with interference arouse from using Analog Devices AD595. This
>is supposed to read the thermocouple, Condition it, linearize, and
>Compensate for the cold junction, then output 10mv per degree Celsius. The
>whole thing works great in my workshop, but I take it onsite and I get a
>odd
>spiking signal. It shows fluctuations up and down of 500 or more degrees.
>It
>almost looks like it has a heart beat... The only thing that is different
>is
>the location. I am running it a max length of 75 feet. With experimentation
>I have found the interference occurs when I extend the length beyond 10
>feet. I am also using K type thermocouples with K type thermocouple
>extensions. I have also tried tyroid coils, capacitors, and resistors. The
>capacitors and resisters helped, but changed the linearity of the output
>from the chip. It need to be accurate to about 1 degree Celcius or less, as
>stipulated be the government!
>
>
Original Message
>From: Dave Mucha <davemucha@j...> [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=f7YAXStYgetI4YFp6LebL7QjdUauvFs_rxvWQHKwC1lYkE7WPtLbE9lumwGOFxH8j3pQwSYn2UBo]davemucha@j...[/url
>Sent: Sunday, January 26, 2003 11:12 PM
>To: basicstamps@yahoogroups.com
>Subject: [noparse][[/noparse]basicstamps] Re: Reading RTD's
>
>
>I'm not sure of the reference to the distance of the run and the
>airport interference.
>
>Thermocouples work on a simple bi-metal principal the asserts that
>dissimilar metals joined will product a voltage that varies with
>temperature. the voltage is low, very low.
>
>Understand that dis-similar metals is the key phrase. copper, lead,
>tin, AND the stuff your thermocouple is made of are all dissimilar.
>That means ANY and EVERY junction can act as a sensing point. the
>terminals on your device may be a reference joint. you cannot use
>any extention of thermocouple wire, it MUST be an uninterupted home
>run all the way from the process to your ADC.
>
>errors can be eleminated by a cold junction reference and calibration.
>Curcuit board temperature monitoring also helps to reduce errors.
>
>You might conssidder an automobile exhause gas sensor as well and an
>RTD.
>
>If you get a transmitter, you will gain a complete circuit and have a
>voltage or current output.
>
>Also, you may need to look at thermowell's. these are the metal
>deviced used to house the sensor to the actual sensor does not come
>in contact to the gasses.
>
>Dave
>
>
>
>
>
>
>
>
>--- In basicstamps@yahoogroups.com, "Phillip Kocmoud" <pkocmoud@h...>
>wrote:
> > Can anyone kick me in the right direction? I am interested in
>monitoring the
> > temperature of an industrial oven. The monitored temperature is
>between 0
> > degrees Celsius and 100 degrees Celsius. I have attempted to use
> > thermocouples, but the distance of the run and its location is very
>close to
> > a major airport, I cannot dampen the interference. I think RTD's
>will fill
> > my bill, but I am unable to find practical information for
>integrating them.
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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