SV: Re: SV: Re: [sdiy] Compensating PTC and NTC resistors
ijfritz at comcast.net
Tue Mar 18 19:57:04 CET 2008
At 12:15 PM 3/18/2008, René Schmitz wrote:
>Hi Neil and all,
>Neil Johnson schrieb:
>>From: karl dalen <dalenkarl at yahoo.se>
>>>So are Elbys calculations right or wrong?!
>>As Ian said, the *equation* is correct, the *numbers* are a little off.
>Correct, but still only of theoretical interest, because you don't really
>know the *actual* tempco of the series resistor. Could be +50 or -50ppm...
>If you stick in 0 for TC2 it degrades to the form I have been using. If
>you stick in the borders, you can use it to assess how large the errors
It sounds like I didn't make the point clearly enough. The error is in the
value of the tempco coefficient, which should be 3440, not 3500. That
makes a significant error in the series resistor, no matter what *its*
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