[sdiy] Current source for tempcos in small quantities

[Ian Fritz]

Hi Harry --

At 04:46 PM 3/9/2003, harrybissell wrote:
>I thought the Q81 were 3300 ppm/K ???

The info I have says 3500 ppm/K. There is some +/- tolerance on this, but I 
don't remember what. To get the best compensation I have needed to add a 
series resistance roughly consistent with the 3500 value.

>In the common use of the tempco (shunting the base of the expo tranny)
>will adding the non-tempco in series cause any problems with the value...
>or do you just change the series resistor to the base to match ?

You have to change the other leg of the voltage divider (whichever 
configuration) proportionately.  In other words, you have to readjust the 
tracking.

   Ian