At 03:24 PM 2/17/2000 , Davidson wrote: >what is a thermistor?? >Bill It's a special resistor made of a material that exhibits an unusually large resistance change with temperature, usually less resistance with higher temperature (which is backwards of most materials). This slope direction is called "negative temperature coefficient." The device may be the size of a pinhead or much larger, and often is embedded in a case like the Vanagon Temp I and Temp II and gauge senders are. Among other uses, it's one of the two common methods of measuring temperature electrically -- the other way uses a thermocouple, which is in essence a pair of dissimilar wires joined at the ends. They generate a (tiny) voltage which is proportional to the temp. difference btw the hot ends and the cold ends. The thermistor method is generally cheaper and less accurate, and requires external power (easily available in a vehicle). Also a thermocouple will probably withstand temps that would destroy a thermistor. Incidentally if you look at the resistance vs temp charts in Bentley, you'll see that Temp I and Temp II have the identical characteristics, though their external appearance is different. Very likely the actual thermistor is identical in both. david David Beierl - Providence, RI http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage" '85 GL "Poor Relation" |
Please note - During the past 17 years of operation, several gigabytes of
Vanagon mail messages have been archived. Searching the entire collection
will take up to five minutes to complete. Please be patient!
Return to the archives @ gerry.vanagon.com
The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.
Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.