Anyone try building the MCD-521-H Compressor?

[oldrocker]

I just bread boarded this compressor from the caseyseffectpage website.  I haven't seen where anyone else had tried it.  The LDR part works as I cover it to block the light the signal gets louder.  What doesn't seem right is the way the LED is set up.  There are two LED's.  One looks like a power on LED and the other has it's polarity swapped around coming off of the same 2.2k resister as the power on LED and shines on the LDR.  That doesn't seem like it would ever work.  Maybe someone else could take a look at this and tell me what you think.

http://smg.photobucket.com/albums/v324/caseyseffectpage/Compressors%20and%20Limiters/?action=view&current=LED-LDR-comp.gif&refPage=&imgAnch=imgAnch1

[oldrocker]

I noticed a -9 volts at pin 4 of the IC.   I have it going to ground.  I can't see the relationship between that and the LED/ LDR though.  I was thinking that maybe the reverse polarity on that LED would somehow be effected by have -9 volts going to the IC.

[oldrocker]

To make this LED/ LDR work I would think I would need a voltage divider and get the voltage down to half the incoming total voltage.  Then put that Vb to pin 5 of the IC and add maybe a .5 cap from pin 7. Then from the cap to the base of an added transistor so that when the guitar signal (Volume) increases the voltage would change and possibly get the LED brightness to change with the variable voltage.  That's as far as I got with it.

[oldrocker]

OK.  That worked.  I hooked the +volt side of the LED to the base of the transistor where the .05 cap went too and the negative side of the LED to ground.  I ended up putting a Vactrol LED/LDR in place of the photoresistor and LED.  It seems to be working but I'll have to test it more in depth in the morning. The cap I used was actually a .047 not a .5 cap.