LA-Light Comp LDR ?

[Pablo]

in Johans schematic there is an LDR near the VU meter...
is it coupled with the same LED as the other LDR? (physically)

could someone shed some light (pun intended) on how to hook this up...
http://www.aronnelson.com/gallery/main.php/v/johan_0/LA_Light_last_one_001.gif.html

Peace,
Pablo

[Pablo]

bump

[Johan]

the idea with the second LDR is to use a reference voltage and that varies with the gain reduction. that voltage is then buffered and sent to the VU, so you have a visiual reference of how much the comp is working.
just place both leds as close to each other as you can, then position both LDR as close to the LEDs as you can and try to make it so both LDRs gets as much direct light as possible...

johan

[Pablo]

Thank you Johan

i've got a few more ?'s if you or anyone else don't mind...

1. my VU meter (Midland) has a 3.6K resistor across the lugs... should i remove it?
2. assuming it does, how do i get the meter to light up?... i only see the two terminal/lugs
3. are there any connections to pin 4 or 8 on the IC used for the meter?
4. can the 100K VR connected to +V & -V near the VU be a trimpot on the board or should it be a potentiometer?

sorry if these are noobish questions... i've never made anything with a VU meter before

Peace

[Johan]

Thank you Johan

i've got a few more ?'s if you or anyone else don't mind...

1. my VU meter (Midland) has a 3.6K resistor across the lugs... should i remove it?
2. assuming it does, how do i get the meter to light up?... i only see the two terminal/lugs
3. are there any connections to pin 4 or 8 on the IC used for the meter?
4. can the 100K VR connected to +V & -V near the VU be a trimpot on the board or should it be a potentiometer?

sorry if these are noobish questions... i've never made anything with a VU meter before

Peace

1: you can probably just leave it where it is...
2: you have to look and see if there is a bulb inside. sometimes there is one sometimes not. sometimes the housing is white transparent(ish) and you can just place a bulb behind it..
3: no, the meter goes to opamp output and to ground. there is a rectifier inside, so you dont need to worry about polarity
4: the pot should be a trimmer, you just adjust it once, when seting the meter. then it should track what is going on with the input but doing the same with a reference voltage(fed to the VU)

..there is no question that doesnt deserve to be asked at least once..
j

[Pablo]

Johan,

I have uploaded a simple Perf-board layout in the gallery... (I think it's right... but i have not built it yet)
http://www.aronnelson.com/gallery/main.php/v/Pablo/

also added a couple pictures of the VU meter i'm using...

You say to "adjust the trimpot once when setting the meter".
Could you further explain the process of how to set it?

Again, Thank you for all your help...

[loss1234]

one thing i am very confused about in the schematic mentioned, is whether the 1k resistor coming off of the output opamp is connected to GRND or to a ref voltage coming out of the opamp below it. (right most middle opamp) (the one with the 2 10k resistors attached..it seems to me to look like a voltage or current source.)

the way the schematic is drawn confuses me a bit. it seems like the VU meter output AND the bottom LDR AND the 47k coming off of the VU ref voltage opamp at bottom, all connect to the output of that middle right opamp.

if so i am confused as to why. is this for offset purposes?  the way things are drawn i am starting to think that either everything connects to an offset OR that the output of the middle right opamp connects to ground at its output.

sorry if i sound like an idiot

can anyone help with this dilemma? I am itching to build this but first want to understand the signal flow

thanks so much!!!

[lolalola]

Aaaaah, I want one! Anyone want to sell me one? Puh-lease? I so do not have the brain capacity to make one, so if you're bored of yours, please email me!