On a sunny day (Thu, 13 Mar 2008 18:41:59 GMT) it happened "Jacques St-Pierre" wrote in :
Hi,
>
>I am designing a product using a Vactrol (led controlled resistor) to
>simulate a RTD.
What is a RTD?
The led intensity will be control by the buffered output of
>a D/A chip.
A LED had light proportional to the *current* through it. So you should drive it with a 'voltage (from your DA) controlled current source'.
opamp
----------- + a k from DA out ---------- LED --- -- - | | | ------------------------------| R sense