> Hi,
>>
>> I am designing a product using a Vactrol (led controlled resistor) to
>> simulate a RTD. The led intensity will be control by the buffered
>> output of a D/A chip. It is working, but to be useful, we have to
>> operate the led in the worst region of it's curve, resulting in very
>> coarse response. Since I do not have enough resolution on this D/A to
>> correct that from software I am searching for a method to render the
>> Vactrol response a bit more linear. Any one can suggest a simple way
>> to create a amplifier using a simple opamp or transistor to reproduce
>> the reverse curve of the led and correct the Vactrol response. I
>> tough that maybe using a led in the feedback path of an opamp may
>> result in a non linear amplifier response and that can be use to
>> drive the Vactrol. Any suggestions?
>
>Can you place a resistor in parallel or series
>to move the region of operation of the LED?
Actually a better place to put it would be in parallel with the LDR. Say about 250 Ohms.