Tremulus Lune Volume drop issue

[BDuguay]

I've got one of the early versions and there is a noticeable drop in volume when engaged. It has a rectangle LED that is not going bright enough to make up the volume difference. I've dropped the current limiting resistor down from 1k to 500ohms but I'm not sure it helped much. Where else to look?
Thanks,
B.

[GibsonGM]

So it's a commercial one, not DIY?   

Maybe read the voltages, Brian...something is going on if "the led isn't going bright enough", y'know?    I'd do that and audio probe, see if you can localize it or if it's everywhere.

[BDuguay]

This one is definitely a d.i.y. and not a kit. The trem itself works but at a much lower volume than bypass.
B.

[mth5044]

Check out the What To Do When It Doesn't Work / Debugging thread and post what you find here.

[BDuguay]

Check out the What To Do When It Doesn't Work / Debugging thread and post what you find here.

I guess what I'm asking is how do I increase the voltage to the LED in the LFO section so that the LED will shine brighter at it's peak to give more volume. I don't know enough about how opamps work in that regard.
B.

[samhay]

How about thinking about this another way. Does your circuit have a trimmer or a fixed resistor across the feedback loop of the second op-amp? In either case, if you increase the resistance here, you will get more gain and thus more volume.

[BDuguay]

How about thinking about this another way. Does your circuit have a trimmer or a fixed resistor across the feedback loop of the second op-amp? In either case, if you increase the resistance here, you will get more gain and thus more volume.

Fixed resistor for sure. There's no trimpot on this circuit. Now, which is the gain resistor is the question. Gotta go to soccer right now.....

[mth5044]

Post the schematic

[GibsonGM]

Ha, I thought you meant the effect CHANGED, and became lower in volume.

Ok, to increase the volume, you'd increase the resistance on the 2nd opamp in the circuit here:  http://www.tonepad.com/getFileInfo.asp?id=84

There is a 25k trimmer between pins 6 & 7 of IC 1...that sets the ration of feedback, and therefore the gain of the circuit.  Tack in a pot (50k -100k? or whatever - layout says it might require up to 100k), set the volume, measure the resistances, and replace with fixed resistors.   Or just get a trim pot and put that in permanently (100k is what I'd use).

[BDuguay]

Post the schematic

I knew this would come up :icon_cry:I'm not sure how to do that...

Ha, I thought you meant the effect CHANGED, and became lower in volume.

Ok, to increase the volume, you'd increase the resistance on the 2nd opamp in the circuit here:  http://www.tonepad.com/getFileInfo.asp?id=84

There is a 25k trimmer between pins 6 & 7 of IC 1...that sets the ration of feedback, and therefore the gain of the circuit.  Tack in a pot (50k -100k? or whatever - layout says it might require up to 100k), set the volume, measure the resistances, and replace with fixed resistors.   Or just get a trim pot and put that in permanently (100k is what I'd use).

Thanks for coming to the rescue! Now, just so I know we're on the same page, we all agree that I need to increase the peak brightness of the LED to match bypass volume and to do that I follow your instructions, yes?

[GibsonGM]

Yes, all you need to do is get the schematic from my post, find the corresponding point in your circuit, and put a trimmer in there.  Be careful not to bust anything while doing this, he he.

I'd like to know what's in there NOW, tho....can you tell?    You must have a fixed voltage divider?   If so, can you tell us the resistor values, and what pins they go to?       There's some reason you don't have a trimmer there, hmmm.

To post a schem or anything from another site you click the "post link" button when you reply....that will add "[] PASTE YOUR LINK HERE [/]" tags to your message.     Paste the URL in between the brackets.   In real life there are no quotes, I added them so you can see the code, and it says URL inside the brackets.  Hope that makes sense, as the code won't display right, since it's code and not text...

Like:  "]www.diystompboxes.com]"

Like:  "www.diystompboxes.com"

[duck_arse]

Code Select Expand

[url] .... some guff.com .... [/url]

use this :

to quot code.

that was some tricky posting.

[BDuguay]

Code Select Expand

[url] .... some guff.com .... [/url]

use this :

to quot code.

that was some tricky posting.

No kidding eh? I'm a wreck...a loose cannon.
I'm going to get it right though, just you wait

[Mark Hammer]

Stick in a 50-100k pot, as GibsonGM suggested.  That will let you turn the depth all the way down to effectiely cancel the tremolo effect, and use the unit as a clean boost with adjustable level.

How's that for value?

[BDuguay]

Let's try this...[url]http://fuzzcentral.ssguitar.com/tremulus/tremuluslayout.gif/url]
It's this version exactly.
B.

[BDuguay]

That didn't do exactly what I thought it would. Where's the option for "post link"?
B.

[snap]

http://fuzzcentral.ssguitar.com/tremulus/tremuluslayout.gif
You slipped the opening bracket before the end of URL.

[GibsonGM]

Yes, you needed to put a "[" after the .gif of the URL.  You were close....

Do you have that trim pot shown on the layout?  It should go between pins 6 & 7 of the opamp, and also connect to the LDR.  That pot adjusts the gain....

[BDuguay]

Ooops, it's an earlier version than that one and doesn't have a trimpot.It's this one
This is another schematic.

[GibsonGM]

It says "trimpot 10k-100k" in the output stage...you sure it's not there, man?  It's INSIDE on the circuit board, it's a small thing, not a big pot on the outside.  You turn it to adjust the gain of that output stage, which is controlling the output volume....

Probably look a little like this:  


**Edit:  I wonder where the "volume" control hooks in?  Probably at the end...so you'd crank the trim up, and use the Vol. pot to control it, I think.  That schem. is probably not the exact one for your unit, I'd say.