Thermistor Voltage Supply Question

[Terminal Crazy]

Hi guys,
quick question for the experts.

I'm playing with a system of thermistors feeding an RS485 Networked ADC to
my computor.

My supply is 5V with a 47k resistor as a Voltage divider with the
thermistor acting as the low side.

Q: Can i use the same resistor to feed multiple channels or is it better to
use a seperate one for each channel?.
I'm only useing std cheap resistors but they vary ie 46.1k and 46.3k for
47k resistors.
If i feed off the same one I can use the same values in my temperature
calculation rather than having to measure each one.

Any thoughts please.
TIA

 

[Sjouke Burry]

Hi guys,
quick question for the experts.

I'm playing with a system of thermistors feeding an RS485 Networked ADC to
my computor.

My supply is 5V with a 47k resistor as a Voltage divider with the
thermistor acting as the low side.

Q: Can i use the same resistor to feed multiple channels or is it better to
use a seperate one for each channel?.
I'm only useing std cheap resistors but they vary ie 46.1k and 46.3k for
47k resistors.
If i feed off the same one I can use the same values in my temperature
calculation rather than having to measure each one.

Any thoughts please.
TIA

Use a current mirror(google) to feed each termistor.

 

[Terminal Crazy]

Q: Can i use the same resistor to feed multiple channels or is it better
to use a seperate one for each channel?.

Sorry stupid question... all the inputs would be connected to the same
point. Duh.

 

[Jasen Betts]

Hi guys,
quick question for the experts.

I'm playing with a system of thermistors feeding an RS485 Networked ADC to
my computor.

My supply is 5V with a 47k resistor as a Voltage divider with the
thermistor acting as the low side.

Q: Can i use the same resistor to feed multiple channels or is it better to
use a seperate one for each channel?.

yes, use a CD4016 or similar to steer the current to the desired
thermistor before reading it. (unless you're interested in measuring
how well insulated the thermistor is)

if you don't have control over when the device takes readings from the
thermistors this probably won't work.

I'm only useing std cheap resistors but they vary ie 46.1k and 46.3k for
47k resistors.
If i feed off the same one I can use the same values in my temperature
calculation rather than having to measure each one.

--- news://freenews.netfront.net/ - complaints: [email protected] ---