oscillator tremolo

[fuzzo]

Hi folks,

I may fail with my danelectro chiken salad rehouse project, So I've a box to fill in and I would like to make a tremolo pedal.

I want keep the "signal part" of tremulus lune (simple a easy to build) but the oscillator part has too many control for what I want. I look for something simpler with a the 2 regular control "depth" and "speed". I'll add a volume pot to have a boost if necessary.

So, do you have another oscillator that can work good with that project ? 

[slacker]

You can get rid of the extra controls on the tremulus lune if you want to, and keep the original LFO. Using this schematic http://commonsound.org/tremulus/tremulusscheme.pdf you just need to:
Remove the Spacing pot and replace R7 with a 470k resistor, connected to the top of R8.
Remove the fine pot, just connect Lug 2 of the speed pot straight to R10.
Remove the smooth pot, just connect pin 3 of the 4558 to the top of C6.
That gives you a trem with just speed and depth, and if you get bored of that you can easily make it into the full tremulous lune.

[fuzzo]

Ok thanks.

So I'll do that, Apparantely the sound of this tremolo is really good.

[Derringer]

here's a schem I have for a one-knob version ... just rate.




and its vero



the 10KA pot is not reverse audio (although that would be ideal), it's just wired backwards to get the taper in the right spot. You can use the standard 100KA pot here as well ... but I liked 10KA better for my application.

[fuzzo]

thanks Derringer for sharring your schematic !

Can you explain me the role of 39K R and 12K coming into the "-" enter of buffer stage ? to have a little reistor like the smooth control does ? I can remove them ?

With the slacker's explanantion I drew that and I don't put Resitors like you did.

[Derringer]

That spot 'was' originally where the 500K smooth pot went. When I made this, I first breadboarded the LFO exactly as the TremLune layout states and then I fiddled with the knobs to get the Spacing, Smooth, and Depth pots where I liked and measured the R on the pot legs. For the smooth pot, it came to something like 400K on one side and 100K on the other. So first I used 120K and 390K in those spots, but realized that it was the ratio of these resistors and not necessarily their exact values that mattered, so I went with lower R's and used 12K and 39K.

[Derringer]

if you just run jumpers like that in place of resistance I imagine it would be like having the smooth pot dead center ... it'll probably work fine.

[fuzzo]

thanks Derringer.

I'm gonna make one without these resistors, just jumpers.

[fuzzo]

I've juste made the schematic I posted above, and that doesn't work , no flashing cycle the led is always shinning. When I turn down the depth pot, the brightness led decrease but the speed knob does the same thign, plus it descrease the voltage at "+" fist stage.

I'm open for all sugestions  

I'm gonna post the veroboard I made.

I've just made the part at left, the oscillator part.



Do you see mistake (based on the scheamtic I post in a early post) ?

[Derringer]

you've got no trace cuts under your IC i.e. you have continuity from pin 1 to 8, 2 to 7, etc etc

I think that you maybe have mixed up the pin numbers as well. For instance, you have jumpers and a track to connect pin 3 to pin 5.

On your schem I see that you didn't put in pin numbers 1, 2, and 3 on one half of the opamp. I'd fix that first because it would confuse the hell out of me if I were trying to make a layout from it the way it is.

hope that helps.

[fuzzo]

Yeah I didn't put cut trackq on the veroboard but there're present on my physical veroboard.

For the schematic, the first AOP is the one used to create the LFO (on the left in veroboard) and the other is  used for the buffer (the right one)

[fuzzo]

I put a 470K R in // with one of 470K which create bias at "+" input. I cut the jumper that links the pin3 to pin5 and replace a 47K. Nothing change

[fuzzo]

little bump