Modulation Fun

[RickL]

I've had some fun the last couple of days by tacking 4ms' Auxillery LFO http://www.commonsound.com/tremulus/auxlfo_modulate.pdf onto my PT80 and AD3208 (available here: http://www.generalguitargadgets.com/ ).

I used a switch to put the LDR in parallel with the speed pot on each of the delay pedals. I also added a 100k Range pot across the LDR and a 100k Predelay  pot in series with the LDR.

I can get everything from wild sweeps to subtle chorus sounds from each of the pedals. I especially like the slapback/chorus combo with the Predelay turned up a bit and the Range and Depth pots turned down a bit.

Sorry, I have no way of posting sound clips but it's an easy build that can also be easily removed if you don't like the sound. I'm also thinking it would create cool sounds when added to any control that is wired as a variable resistor.

[thumposaurus]

I just fiished up some testing with the same circuit tacked onto an Arion analog delay,  I think I need to try some different LDR's as I'm not getting as good of a range as I think I should be, or maybe it could be the analog delay, I was getting some cool noises out of it though.
I've got it wired up to some alligator clips so I'm going to start pokeing around in some other pedals and see what I come up with.

[mathflan]

Hi!

I finished to build my PT-80, and what you said in this post intereste me a lot.
But I'am a little silly.. Can you explain me how can I conenct this Aux Lfo board to my Pt-80, wire etc...

[RickL]

Build the auxilery LFO board seperately and temporarily power it with its own 9 volt battery to confirm that it's working correctly. The speed control should adjust the speed of the flashing LED and the depth control should control the LED intensity.

Connect the LDR across the two lugs of the speed pot of the delay and make sure the LED is shining on the LDR. I used a rectangular LED because it fits the layout well but any LED should work.

Once you've confirmed that the auxilery board will actually modulate the delay, hook the power and ground wires from the auxilery board to any convenient place on the delay board.

You may want to hook a 100k pot in series with the LDR and another one in parallel with the LDR for added control.

[mathflan]

merci beaucoup rick..

[mathflan]

Rick I would to ask some questions :

- Do you use logs pots or linear pots for LFO with LDR?

- How can I use lfo on delay time without delay effects of the pt-80??

Thanks

[RickL]

I believe I used linear pots. I'm never too picky about taper on pots because taper only affects the 'feel' of the control, not whether it actually works or not.

I don't think you can use the LFO without at least some delay time. The chorus sounds are acheived by varying the amount of delay. If you're hearing the chorusing imposed on top of a noticable delay time try lowering the delay with the pt-80 delay pot. Chorus tends to sound better by varying a fairly short delay. The LDR is in parallel with the pt-80 delay pot so it should just vary the resistance down from where ever the delay pot is set.

I suppose you could try using a switch to disable the pt-80 delay pot and use only the LDR to set the delay time. I think this will give more extreme modulation sounds than having the LDR in parallel with the delay pot.