how to connect AD595 thermocouple amplifier?

[jex]

the picture below is my connection of the thermocoupler amplifier, i realise that that is no doted for me to guide as pin number 1,so i according the data sheet and assemble it, the orange colour wire is grounded n yellow colour wire is the voltage supply but when i use digital multimter to test the voltage, no voltage shown, the thermocouple position i put correctly already, is it my grounded pin got problem ? cause my voltage output need to connect to my usb 6008

[AnalogKid2DigitalMan]

Have you tried connecting pins 8 and 9 together and measuring between pins 7 and 8? Don't understand why you have wired pin 12 to common.

For reference, with the notch on the left side of the chip, pin 1 is the lower left.

Refer to page 3 of the pdf for single supply operation.

http://www.analog.com/UploadedFiles/Data_Sheets/AD594_595.pdf

[jex]

pin 8 and pin 9 have to connect together in order make it into 1 pin assigned? then our DMM is it positive terminal connect to that pin 7 and 8 and the negative terminal connect to groud?? Do i connect a voltage regulator 1st be4 i use the power supply of 5V? then what is the dotted line stand for under the line iron ( cromel) there?

[jex]

oh....ic....thx what is the dotted represent under the iron (cromel) there ? any connection required ?

[AnalogKid2DigitalMan]

The line below the iron does not appear to connect to ground (common) since there is no dot.

I see no need to use a regulator if you are powering it with 5V. Looks like chip will accept a range of 5 to 30V

Your output voltage would be measured as you assumed. DMM or DAQ + in to pins 7/8, DMM or DAQ - to ground (common). You should also wire pin 13 to ground if alarm is not used.

IMPORTANT- App note states that you must directly connect your thermocouple to pins 1 and 14 or use thermocouple extension wire. looks like you are not doing that and this will create measurement errors.

Have you read the entire App note?

[jex]

cannot use the normal wire? thermocouple extension cable same as the thermocouple wire ? the red color on the k type thermocouple wire is terminal negative then should be connect to negative terminal on the thermocouple, rite ? but why we need to use the thermocouple wire since the metal of 2 terminal provide voltages and we just require to use the normal wire to transfer the voltage ? then the dotted line can ignore it ? ya..i was wrong by ground at pin number 12.

[Robert_F]

The doted line connecting the Iron (Chromel) lead of the thermocouple to common is used to compensate for runaway conditions when using an alarm.  If +In is connected to common, then the circuit is configured for downscale output.  If –In is connected to common, then the circuit is configured for upscale output.  This is done to ensure that most runaway conditions are avoided. 

More information on this subject can be found on page 7 of the datasheet.

[AnalogKid2DigitalMan]

Direct from the App Note:

The thermocouple wire inputs connect to Pins 1 and 14 either directly from the measuring point or through intervening connections of similar thermocouple wire type.

If you use different wire you will be creating another thermocouple junction that will affect your readings if the temperature of the connection is different from the chip. It should be a small error since your connections are close to the chip, but an additional error nonetheless. Connections of dissimilar metals are what make thermocouple work.

I would omit you connector block if possible and use the thermocouple leads as a direct connection to the chip.

[jex]

thx..i will connect n see 1st

[jex]

oh..can use the old thread? i thought it will deleted after several days....sorry, i am newbie on forum, at room temperature it only show 5.4mV when i measure using multimeter and my value will be out cause i using normal wire to connect because i will do my own calibration later on, when i use lighter to heat, the value doesn't increase only when i use finger to press the tip

Message Edited by jex on 06-15-2007 10:02 AM