LDR in Trem Lune

[Funky_Tomo]

Hey there all. Just checking out the Lune Tremolo and wanting to figure out what use the LDR has.

What is it specifically used for?
Do i need to use it? Can I use a Trim pot instead?
How is it setup normally EG: Outside, inside, facing LED, facing up, Down?

Im stumped, ive searched the DIYsb.com for about and Hour and no where can I find useful info on this. Apart from the actual diagram.

Thanks for your help. (in advance)

[darron]

i've never built one, but i'd say the LDR sits so that as much light from the LED hits it, INSIDE the box as far away from other light sources. the led would flash at the rate of the effect, and the light will be picked up as a resistance to adjust the volume and cause the tremolo effect.

if i built one, i'd cover the ldr and led combo somehow in the box, and also mount another led on the surface that was on when the unit was on, but also had a small amount of the fading effect so you could see how fast the tremolo is going.

[Funky_Tomo]

Ah ok, so it uses the light to "open" up the sound to pass through the ldr. Thats interesting.

Anyone else feel free to help a Noob out.

[boogietube]

The led / ldr basically controls the effect. You can't omit that part. You can use a Vactrol VTL5C/2 in place of that. I might have one to spare if you want it. E-mail me and I'll check for it.  Normally the led and ldr face each other very close. One is a light (led)and the other is a sensor(ldr).  If you use this combination it has to be dark to work. Some people build their own.
Here's a link to some info on this:
http://www.generalguitargadgets.com/index.php?option=content&task=view&id=123&Itemid=141
If you use the vactrol, it is sealed and will work in the light.
Any more questions, I'll try to help.

[darron]

hi boogietube. i'm curious what a vactrol is? is does it work the same as the led/ldr combo, or does it just convert a voltage into a resistance? i'd assume that the led/dlr combo would give the pedal it's mojo of ultra smooth sweeps, instead of a constant perfect oscillation? sealed inside of an almost watertight aluminium box, i doubt that there would be much of a problem with the ldr picking up extra light, and if it did, wouldn't that just adjust the depth a little bit? its a good point though to have them close. i think i said above i'd also cover them somehow. i think the best thing would be to put them in a tube with the led up on end, the ldr up the other end, and something reflective like aluminium foil (but less conductive of juice) lining the inside of the tube for a nice smooth tremolo sweep

[markm]

This may help you out a bit; http://www.blackboxmusicfx.com/diy.html

[smallbearelec]

hi boogietube. i'm curious what a vactrol is? is does it work the same as the led/ldr combo

The generic term for a sealed LED/LDR combo is "photocoupler" or "opto-isolator." Vactrol is the trade name that Perkin-Elmer Vactec uses. Silonex is another company that still makes them.

For the Tremulus Lune, a VTL5C2 or VTL5C3 will work, or possibly a Silonex NSL-32. You wil see references in other designs to photocouplers that were made by Clairex and Hamamatsu, but they are now out that business.

[darron]

that's really cool. i'd never heard of these. maybe i've seen them and not known what they were. sounds like it would sort of take the fun out of it lol.

thanks for teaching me on someone else's thread (:

[$uperpuma]

the vactrol is ideal in that its already sealed and cant shift

[KMS]

You could also use a CLM6000 if you can find it........some shops still have some left.  It is the same as Vactrol just different spec sheet.

If you make your own you can get a better responce by playing with different LEDs and LDRs.

I have made many (at least ten) and I find that purchasing several packages of LDRs allows cherry-picking of the LDR and you can find some that will go below 100 ohm (80ohms) light resistance with a 1.5 VDC LED rated at 1500 up to 3000 using only .004 amp and still have over 2Mohm dark resistance.

[Ge_Whiz]

Beware! Most "opto-isolators" are a combination of a LED and either a photodiode or a phototransistor, not usually a LDR.