RCTime circuit and Temperature
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Hi All,
I have a RCtime circuit measuring battery voltage on a robot outside. The
indicated voltage seems to vary with the temperature. Is the components
including the stamp2 affected by the temperature? If so can I get components
(resistor, cap) thats not affected by temp. The voltage is swinging about 0.6V
over a 20 deg range...Battery is 12V.
Thanks for any help
Jerry
I have a RCtime circuit measuring battery voltage on a robot outside. The
indicated voltage seems to vary with the temperature. Is the components
including the stamp2 affected by the temperature? If so can I get components
(resistor, cap) thats not affected by temp. The voltage is swinging about 0.6V
over a 20 deg range...Battery is 12V.
Thanks for any help
Jerry
Comments
> I have a RCtime circuit measuring battery voltage on a robot outside.
> The indicated voltage seems to vary with the temperature. Is the
> components including the stamp2 affected by the temperature? If so
> can I get components (resistor, cap) thats not affected by temp.
> The voltage is swinging about 0.6V over a 20 deg range...Battery is 12V.
I have a pretty long essay on temperature effects on RCtime and measuring
battery voltage at:
http://www.emesystems.com/BS2misc.htm#RCtime
Are you using a stable capacitor, like film? Some monolytic ceramic
capacitors or electrolytic capacitors have quite large temperature
coefficients. The threshold of the PIC also changes with temperature, but
over a 20 deg C range that would account for 1% to 2% error. BTW, battery
voltage does really fluctuate with temperature.
-- Tracy Allen
Electronically Monitored Ecosystems
http://www.emesystems.com