Any particular thermistor you would recommend?
Scott
On 07/27/2010 09:07 PM, saidj...@aol.com wrote:
Hi Scott,
yes the pads are there, you can use the through-hole pad right next to C67
and a standard ground pad for the Thermistor. There will be 10.5V across
the thermistor. Connect the thermistor to your Rb case.
You should be able to connect two 10K Thermistors in parallel to get a good
reading without excessive self-heating of the thermistors, while
generating enough current through them that can be measured by the ADC.
You can check the thermistor current using the meas? command. If the
thermistor is not drawing enough current for the ADC, then simply place a 2.2K
resistor in parallel to it.
The software needs to be enabled to support measuring and applying a tempco
correction, by default I think the boards were shipped with only aging
compensation enabled.
Us the following command to enable tempco correction:
serv:tas 2,288,600,50,0.05
Check the settings with:
serv:tas?
The first number is the mode (0 is all off, 1 is aging only, 2 is aging and
tempco correction). The second number is the memory usage, 288 points in
this case. The third number is the sensing frequency in seconds, so 10
minute intervals in this example. 288 points * 10 minutes is 48 hours of
memory.
The fourth number is the maximum phase offset allowed for a sense point,
in this case +/-50ns. The last item is the required frequency error
estimate for a sense point, in this case +/-0.05ppb.
bye,
Said
In a message dated 7/27/2010 17:07:31 Pacific Daylight Time, sm...@intt.net
writes:
Said, Did the OEM units (from way back) ship with an open pad for the
thermistor? I thought that wouldn't work unless it was drawing oven
current from the Fury. It would be neat to add some tempco into the mix
instead of just trying to shield it from HVAC cycling. The particular
LPRO-101 that I'm using now, doesn't seem to be as sensitive as others
to temp. I was using a different LPRO originally and when I plotted the
Fury board temp sensor with GPSCON you could see the impact of the
cycling, now with this one you would be hard pressed to pick it out.
The X72 was very sensitive to temp changes, EFC tracked the temp quite
well.
Scott
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