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Author Topic: Using an LM34 temp sensor  (Read 711 times)

wwtolman

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Using an LM34 temp sensor
« on: July 25, 2010, 08:21:41 PM »
Any reservations I should know about using a LM34 as a temperature sensor with the IoBridge?
I figured using the supplied ground, +5 and Analog input, I should be able to read the voltage for the temp reading.
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wwtolman

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Re: Using an LM34 temp sensor
« Reply #1 on: July 27, 2010, 11:37:24 PM »
Well it works…kind of. Using the setup described above I get a voltage reading of .723. So at .10V a degree (F) that should be 72.3 degrees. It seemed a bit off, I measured the output of the LM34 and it was .705 V. (The AD Raw reading was 145, the supplied voltage from the ioBridge is 5.06)
Any idea why the display reading would differ from the input reading?
 ???
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jason

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Re: Using an LM34 temp sensor
« Reply #2 on: August 03, 2010, 11:08:38 AM »
It could be an impedance mismatch.  If so, a 100k resistor between the LM34 and the analog input may help.
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Jason Winters
ioBridge Developer

wwtolman

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Re: Using an LM34 temp sensor
« Reply #3 on: August 03, 2010, 11:47:34 PM »
Tried using a 100k between the LM39 and the analog input as suggested
The display variance the widget showed was even greater than before.
Meter showed .710, display showed .793
I’ll keep trying,
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