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Post by marcello on Oct 19, 2021 5:09:37 GMT -5
Good morning
we purchased a TP-204-NI-N2_S09 sensor which includes the DT-670 silicon diode sensor. I ask if we have to limit the recommended supply current to 10 micro A through terminals I- and I + or it is sufficient to apply a power supply of for example 24Vdc and the current is automatically limited by the sensor.
Thank you
Marcello
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Post by Lake Shore Jeff M on Oct 19, 2021 6:33:58 GMT -5
Marcello, For proper operation and temperature measurement, the DT-670 Silicon Diode must be excited with a 10 micro Amp constant DC current. Ues of any other current or voltage source will result in incorrect temperature measurements and can possibly cause the diode to fail.
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Post by marcello on Oct 29, 2021 10:12:42 GMT -5
Good evening
when measuring temperature with TP-204-NI-N2_S09 sensor which includes the DT-670 silicon diode sensor, we detect a continuous oscillation of output voltage of about 0.3V for which we do not know the reason. The value of the voltage read at the temperature of -196 ° C is 0.930V against the 1.027594V of the table you supplied, despite the stabilized power supply is 10 micro A.
Can you give us any indication on this?
Thank you
marcello
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Post by Lake Shore Jeff M on Oct 29, 2021 13:14:52 GMT -5
The simple answer is no, if the temperature and excitation current are stable, the resulting voltage drop across the sensor should be stable which would result in a stable temperature being calculated.
I am a little confused by the numbers you list. If you are at 196°C, that would be 469.15°K and would be a voltage of approximately .16V across the diode sensor. Are you referring to the voltage output from a Model 231 transmitter card or a Model 211 Monitor? If yes, please tell me what range you have selected along with the curve and I/O switch settings on the 231 card. You can send a picture of the DIP Switch settings to support@lakeshore.com
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Post by marcello on Nov 1, 2021 14:11:48 GMT -5
Good evening
the measured temperature is -196 ° or 77K and the sensor output voltage was measured with a digital meter indicating 0.930 Volts.
From the table supplied with the sensor at the measured temperature of 77K we should have read 1.027594 Volts.
The reading of this voltage on the tester display is not a fixed value but fluctuates, ie it varies between 0.80 Volts and 1.06 Volts.
the probe is powered by a simple electronic board powered at 24Vdc to generate a constant current of 10 microA.
Thank you
Marcello
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Post by Lake Shore Jeff M on Nov 1, 2021 14:27:18 GMT -5
You are correct that the voltage should read 1.02... when you are at 77K so the only thing I can offer is to have you send an email to support@lakeshore.com and provide the serial number of the probe, note that the probe is not reading correctly at 77K and provide your complete contact information, name, name of the company or institute you represent, address of the company and your contact phone number. We will need the probe returned to perform a warranty failure analysis.
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Post by marcello on Nov 4, 2021 8:53:33 GMT -5
Good evening
we proceed with other tests and only then will we let you know for the return of the instrument under warranty.
Thank you
marcello
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