Here is a layout for the Rebote LFO mod.

[mcasey1]

This is for adding an LFO to a PT2399 based delay.  Allows for a subtle chorusing sound and can be set up to switch in and out of the circuit.  3mm red LEDs should work well in this layout.  Let me know if any errors are spotted.  Schematic:



Layout:


IC can be a TL072.
Again, let me know if there are any errors and thanks to Nick for the schematic.

[soggybag]

I tried to make something like this about a year or two ago. I used the Commonsound AUX LFO for mine. It worked OK. But I could never get the LDR resistance right. So the range of the effect was not very good.

Which LDR do you recommend?

[mcasey1]

Look at the first image, the schematic.  A recommended LDR value is written there.

[soggybag]

I was wondering what part number they might recommend.

[oldschoolanalog]

Looks like a job for the CLM6000.
http://www.smallbearelec.com/Detail.bok?no=353

[Fp-www.Tonepad.com]

nice work!

[markm]

nice work!

Yes.

[mcasey1]

Thanks.  This is probably my 4th layout, so I apologize for the obvious lack of component placement skill.  I will be working on it, and starting a gallery profile soon.  This layout will be available there.

[mcasey1]

A revision and a PnP image.

[ulysses]

i am unable to see the original schem or layout.

could you please post a link to the schem and any documentation?

cheers
ulysses

EDIT: and congrats on posting something that others can use

[mcasey1]

http://www.diystompboxes.com/smfforum/index.php?topic=57256.0

Schematic here.  Thanks Ulysses.  You can't see either of the layouts that I posted?

[ulysses]

hey matt

have you built this? any chance you can give us some audio demos?

cheers
ulysses

[snoof]

i'd love to hear some samples as well

[Stompin Tom]

very cool... like a poor man's (digital) memory man?

[mcasey1]

Ha unfortunately, no.  I haven't even built the Rebote yet, but I am awaiting parts.  But as soon as I etch the board for the Rebote, I will etch the LFO layout on the same board and I will be building them together.  So as soon as I can get samples up I will.  Here is a link to a sample clip:

http://www.diystompboxes.com/smfforum/index.php?topic=17340.0
MODIFICATION:  This is not the exact same LFO circuit or setup, but should achieve close to same result.

So, to clarify, the layout IS unverified, but looks good to me and I am assuming to others. 

[Seljer]

heres a soundclip of my rebote with the delaytime modulation
http://aronnelson.com/gallery/album113/rebotechorus
I only have it breadboarded together atm, I used one of the vactec optocouplers

I built this a few months ago, not off the same schematic but the same principle underneath (the same type of LFO and everything)

[soggybag]

I remember seeing a post on another forum about a LFO mod for the PT2399 delay that used a BJT instead of an LDR.

[yeahyeah]

The LDR and depth pot values can vary,

The one I used for the schem was 5k light 500k dark I think. That with the written depth pot value, you are only getting a couple Kohms of resistance change... so if it's not deep enough, use an LDR with a lower "on" resistance or a bigger pot. (try a new LDR first, if the depth pot gets too big it will mess with the overall delay time too much)

On the schem, the depth pot and ldr are in parallel, this is because you really only need a few Kohms of total resistance to shift the pitch...and i wanted a more subtle tape echo modulation. but you can use higher values for crazy pitch shift modulation.

the best LDRs for this setup have a light value <20K and a high dark value

there are other ways to set up a depth control, but this seemed to work best with the parts that I had and it turns itself off when the depth is at full CCW.

Heres a cheap place to buy alot of LDRs, http://futurlec.com/Photocells.shtml 
They take a long time to ship and the shipping is expensive so pick up some other things while you're there.(50 cent pots!!!)

[alecacca]

sorry, i haven't understand where i must connect the "delay time" wire from the LFO circuit to the circuit of the delay..  where i must put the wire? the delay pot si directly connected to the IC..
?   thanks!!    alex

[mcasey1]

Pins 3 and 4 of the IC are directly connected to ground.  Place a wire from the number 1 lug of the Delay pot to the LFO circuit.  It is hard to see on the tonepad layout because the traces are green and gray and you think that they do not connect.  Zoom in and examine the 3,4 pins of the IC.  They are connected straight to ground.