Easy Vibe LDR's

[Triffid]

Hello,

I would like to create the Easy Vibe found at www.geofex.com but I want to make sure it has a decent sound first.  Does anyone have any experience building this?  Also, looking at the pdf it didn't seem obvious what kind of ldr's to use for the curcuit... anyone have any ideas on this, and where to get them?

Here is a link to the pdf...
http://www.geofex.com/PCB_layouts/Layouts/easyvibe.pdf

Thanks in advance for any help

[Mark Hammer]

Ideally, you want somethng with a reasonable range, say 1meg-off/1k-on, so that you have something you can tweak.  You can always trim back on sweep range but you can't add more than is already there.

Also consider that the values of the caps are intended to spread phase shift more gently across the entire spectrum so as to reduce the obviousness of notches.  The amount of phase shift is fixed on a per-octave-above-this-frequency basis but that frequency is set by the joint action of the LDR and cap.  What this means is that you start off with the designated cap values, but if you can't find a quartet of similar LDRs, you can play with the cap value accompanying the dissimilar LDR and eventually get something closer to the sound you want.

[Triffid]

Thanks... that helps a lot.  Do you have any idea where I could get the ldr's.  I tried search at Mouser and couldn't find any, but I am probably looking in the wrong spot.

Thanks again

[Triffid]

Well... I found the photocell section at Small Bear (I didn't even know that meant the same thing as LDR... i'm learning).  One of the items is...

Clairex CL9P4 Plastic-cased photocell for the Easy Vibe and other modulation effects. Fast response, Dark Resistance 20 Meg, Light Resistance 20K

It has a lot more resistance then the one previously mentioned.  I will probably start of with this one and see how it sounds.  Thanks for you your help.

[Joep]

I breadboarded the easyvibe with two VTL5C3/2, worked nice. Easy too.

I ordered two more to get 8 stages, I'll have to breadboard is soon.....

Bye,

Joep

[Tobias Karlsson]

Well... I found the photocell section at Small Bear (I didn't even know that meant the same thing as LDR... i'm learning).  One of the items is...

Clairex CL9P4 Plastic-cased photocell for the Easy Vibe and other modulation effects. Fast response, Dark Resistance 20 Meg, Light Resistance 20K

It has a lot more resistance then the one previously mentioned.  I will probably start of with this one and see how it sounds.  Thanks for you your help.

I like these from Small Bear;
Photocell For Univibe/Neovibe Mouser #338-54C679

They seems to be lower in resistance compared to the one that is recommended to the Easy Vibe at SB.

When I measured with the same led setup and battery. That means that you will have, as Mark said, more to tweak, and when settting the trimput at the same value the sweap will go "higher" with the LDR's from Mouser.
When adjusting the sweap to be egual between te two different LDR's the Mouser should draw a little bit less current.

This is just my own findings :-) I'm not one of those "wizards" :-)

Tobias Karlsson in Sweden