I/O project
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Posts: 46,084
I'm working on getting what is, effectively, thermocouple input into
a BS2. T/C output is in microvolts, and not clean, flat DC. The
device I am using emulates a thermocouple, and as such is actually a
little worse. What has me stumped for the moment is that when I
amplify the signal (741) the erratic nature of the t/c output is
amplified as well. The result is that the stamp sees a wider range
of output from the ADC than is desirable, and it's only doing it's
job.
If I could speed up the stamp and take samples to average from, that
would work well, but, as we all know the stamp has it's biggest
limitation here.
Has anyone had any experience conditioning this kind of small signal
so I don't need to use a bulky bit of programming to do so?
TIA (Thanks in advance),
Chris Loiacono
a BS2. T/C output is in microvolts, and not clean, flat DC. The
device I am using emulates a thermocouple, and as such is actually a
little worse. What has me stumped for the moment is that when I
amplify the signal (741) the erratic nature of the t/c output is
amplified as well. The result is that the stamp sees a wider range
of output from the ADC than is desirable, and it's only doing it's
job.
If I could speed up the stamp and take samples to average from, that
would work well, but, as we all know the stamp has it's biggest
limitation here.
Has anyone had any experience conditioning this kind of small signal
so I don't need to use a bulky bit of programming to do so?
TIA (Thanks in advance),
Chris Loiacono
Comments
Well, offhand, two things... [noparse][[/noparse]1] A 741 isn't the best choice for low-noise
amplification. Have you looked into something better for this job, such as
OP-07, OP-27, etc? [noparse][[/noparse]2] Have you tried a simple integrating network (R/C)
upstream of your ADC?
>I'm working on getting what is, effectively, thermocouple input into
>a BS2. T/C output is in microvolts, and not clean, flat DC. The
>device I am using emulates a thermocouple, and as such is actually a
>little worse. What has me stumped for the moment is that when I
>amplify the signal (741) the erratic nature of the t/c output is
>amplified as well. The result is that the stamp sees a wider range
>of output from the ADC than is desirable, and it's only doing it's
>job.
>If I could speed up the stamp and take samples to average from, that
>would work well, but, as we all know the stamp has it's biggest
>limitation here.
>
>Has anyone had any experience conditioning this kind of small signal
>so I don't need to use a bulky bit of programming to do so?
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!
ad595 for type K, you feed the output of these ic's to an a/d converter and
your done.
all adjustments and ice temp references are done on the chip.
the signal is very clean, and gives a good stable output.
www.analog.com
Norm & Monda
Cozy MK IV #202
Ford V-6 Powered
Original Message
From: "Chris Loiacono" <chris@a...>
To: <basicstamps@egroups.com>
Sent: Thursday, July 13, 2000 11:25 AM
Subject: [noparse][[/noparse]basicstamps] I/O project
> I'm working on getting what is, effectively, thermocouple input into
> a BS2. T/C output is in microvolts, and not clean, flat DC. The
> device I am using emulates a thermocouple, and as such is actually a
> little worse. What has me stumped for the moment is that when I
> amplify the signal (741) the erratic nature of the t/c output is
> amplified as well. The result is that the stamp sees a wider range
> of output from the ADC than is desirable, and it's only doing it's
> job.
> If I could speed up the stamp and take samples to average from, that
> would work well, but, as we all know the stamp has it's biggest
> limitation here.
>
> Has anyone had any experience conditioning this kind of small signal
> so I don't need to use a bulky bit of programming to do so?
>
>
> TIA (Thanks in advance),
> Chris Loiacono
>
>
>
>
>
>
>I'm working on getting what is, effectively, thermocouple input into
>a BS2. T/C output is in microvolts, and not clean, flat DC. The
>device I am using emulates a thermocouple, and as such is actually a
>little worse. What has me stumped for the moment is that when I
>amplify the signal (741) the erratic nature of the t/c output is
>amplified as well. The result is that the stamp sees a wider range
>of output from the ADC than is desirable, and it's only doing it's
>job.
>If I could speed up the stamp and take samples to average from, that
>would work well, but, as we all know the stamp has it's biggest
>limitation here.
If you are not doing so now, use the Stamp II SX @ 50 MHz .
See the Parallax website for details [noparse][[/noparse] www.parallaxinc.com ] .
>Has anyone had any experience conditioning this kind of small signal
>so I don't need to use a bulky bit of programming to do so?
>
Tracy is the thermocouple guy, and I'm sure he will respond to your
inquiry. You might want to check his EMESYS company website at
[noparse][[/noparse] www.emesys.com ] for additional information.
>TIA (Thanks in advance),
>Chris Loiacono
Surely
Regards.
Bruce Bates
AD594 is a thermocouple converter that takes T/C input and provides
10mV/degreeC output - perfect for the ADC0831 ADC to stamp solution!
Original Message
From: Chris Loiacono [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oHl2D0V-jqsfO16qEUUd7XJfwUKF_old4Ft4De5Rd9QX1d_oe076PPgs6Lk5VGfPxjfeipbCMQV6DUTe2MEs_rlVKmU]chris@a...[/url
Sent: Thursday, July 13, 2000 11:25 AM
To: basicstamps@egroups.com
Subject: [noparse][[/noparse]basicstamps] I/O project
I'm working on getting what is, effectively, thermocouple input
into
a BS2. T/C output is in microvolts, and not clean, flat DC. The
device I am using emulates a thermocouple, and as such is actually
a
little worse. What has me stumped for the moment is that when I
amplify the signal (741) the erratic nature of the t/c output is
amplified as well. The result is that the stamp sees a wider range
of output from the ADC than is desirable, and it's only doing it's
job.
If I could speed up the stamp and take samples to average from,
that
would work well, but, as we all know the stamp has it's biggest
limitation here.
Has anyone had any experience conditioning this kind of small
signal
so I don't need to use a bulky bit of programming to do so?
TIA (Thanks in advance),
Chris Loiacono