Help me adjust that led dimmer circuit

Started by Le québécois, December 29, 2012, 09:40:08 PM

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Le québécois

Hi,

I have this LED dimmer circuit on the breadboard.
http://www.seekic.com/blog/project_solutions/2011/08/22/30_mA_LED_Dimmer.html

I replaced P1 by connecting it to a 100kaudio pot installed in a old crybaby shell. The LED (D2) is tigh to a LDR inline in the audio path of a tremulus lune circuit. This allow me to rock the crybaby which make D2 blink accordingly and the LDR modulate my tremolo.
After some tweaking with R2 and the LDR, it work!  :icon_biggrin: At first, the sweeping was bad because the pot in the crybaby is audio thus it did'nt swell enough for me. It was more on and off. To correct for that, I need a linear pot but buyng a crybaby pot is not an option in my case. I decided to play with the taper of the pot according to the "Secret life of pots" at GEOFEX and the sweeping is better. It is not officialy mention that we can linearize a log pot in that good reading but it seem to work. My build now swell up and down almost to my satisfaction (it could be better).

My question is : does one of you guys know how to mod the opamp part of this circuit to make it antilog sensitive (thus correcting) my audio pot problem? Sometime a well place capacitor or resistor may do the trick but I'm clueless as how to do it or if it's possible at all without redesigning the whole thing.

thank you