[sdiy] rev log voltage ic??

[synthplayer88 at spymac.com]

Hey thanks Steve!  :)

I have that app note here but just haven't had the time to read it, I guess I am
just looking for a quick way out where there has been a circuit been built and
commonly used/tested without worrying about tweaking the circuit and try to make
it better? Since I just don't know enough yet to do so and by them time I do, I
wouldn't have anything built..... :(

BTW, I found another app note which might be a bit better for circuit rip off? :)

http://www.national.com/an/AN/AN-30.pdf#page=1




On Wed Jan  5  6:24 , Steve Ridley <spr at spridley.freeserve.co.uk> sent:

>
>
>> If not, does everyone just use a transistor on the feedback of an op amp and
>> gound the base to get the log voltage?
>
>Yes, but it won't be very good or stable.  Search for exponential or
>logarithmic converters on the internet.  There are some standard 
>circuits that use a dual opamp and a transistor pair.  Start here.
>
>www.web-ee.com/primers/files/AN-311.pdf
>
>
>
>Steve  
>
>
>
>
>> I would like to avoid transistors if possible since I always seem to run into
>> problem with biasing, am more of a no brainer op amp kinda guy...... :(
>> 
>> 
>> 
>> 
>
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