log opamp question

[electronics man]

I have been experimenting with log opamp circuits. the equation is Vout = K ln (Vin/Vref). I am confused as to what k is and Vref is can someone help? i am using the standerd opamp with a diode in the feed back loop of an opamp.

[Rory]

http://en.wikipedia.org/wiki/Log_amplifier

[electronics man]

I looked it doesnt explain much

[electronics man]

All it does is say what it is not explain it

[Rudane]

electronics man: Follow the first link in external references and scroll down to the section around equations 5 and 6. Look at the two equations and deduce what K must be from them.

[Rory]

Sorry I was terse, didn't have time to make a long-winded explanation. To further confuse you, and instead of spoon feeding you information I could possibly get wrong,  here is a credible source for you to study.

Analog Device's Log Amp Basics tutorial.
http://www.analog.com/static/imported-files/tutorials/MT-077.pdf
 
Go to page 4 for the diode log amp.

The point is, sharpen your Google-Fu. Research it for yourself from manufacturer's data sheets, appnotes and tutorials instead of asking on a forum where some pendantic know-it-all can give you the wrong answer.