LDR attenuator, the passive preamp update.

This is actually version one of the project! I was using a multitude of LEDs with different colors and burnt several due to overvoltage! I had a bunch of light green colored ones and it works without much noticeable difference! This version 1 prototype did not last long enough... ;)

This is the two excellent DC voltage controllers(using MOSFET) that I acquired. Working voltage is from 6VDC to 15VDC.. I see a multtude of applications here ;) Suffice to say, it works beautifully in this project!


This is my second prototype I have built to investigate the performance of the LDR preamp. Suffice to say, the initial sound quality that I got was really promising! It had all the SQ that was mentioned. The only quirks that I encountered was the non-linearity of the LDR itself. Evenhough I managed to control the intensity of the light proper but the LDR did not response as linear as I want it to be.. something for me to look into.. The shroud used to isolate the LDRs is not shown here for clarity of the unit.

As earlier mentioned, I was thinking of using alternate source of light instead of the LED which I think did not give linear light control as per original circuit.
After much thinking and hunting.. I found a DC controller based on PWM(Pulse Width Modulation) which would work better than linear control eg. variable voltage control.

Conclusion?
The LDR preamp works great. No wonder diyparadise resorted to digital volume control on their LDR volume control to properly managed the attenuation.
If you don't have any preamp and itching to build one.. go for this one. It is cheap and simple!