wah wah with optocoupler (need help with optocoupler)

[birt]

RG mentions in his "technology of the wah" how to use a crackly wah pot to control the brightness of a led and how to use an LDR as a variable resistance to ground that way.

i'm a bit tired of trying different led/LDR combos since LDR's are quite expensive and hard to get here (and it leaves you with a batch you can't use). i was thinking about using vactec vactrols but then i found a quite cheap alternative. i worked at the belgian Vari-Lite (moving light heads, maybe you know the brand) distributor for a very short period (i'm still a student) and saw in a schematic of one of those fixtures and i believe that they use ILCT6 optocouplers as variable resistance to ground. So i looked for a datasheet but i can't understand those things very well and i really don't know if i can use them to control a wah. i understand it's a chip with two optocouplers that are made of a led and a phototransistor with only collector and emitter pins.

maybe someone can check this datasheet and help me out? if this is a usable optocoupler this might be a good find for the DIY community


http://www.datasheetarchive.com/search.php?q=ilct6&sType=part&ExactDS=Starts

bert

[DEZREJECT]

im lookng for something like this.. look on my post.. you might be interested in checking out http://www.morleypedals.com/ and looking at their schematics.. they use an optical circuit... its pretty awe-inspiring and for DIY it looks very do-it-able

[zachary vex]

i would always suggest working with photoresistive cells rather than phototransistors for audio circuits.

[DEZREJECT]

damn.. zachary vex.. the man behind zvex.. i feel honored for being a part in/of your reply! ... not to down anyone else.. but dude ur pedals are like of my dreams lol.. i just cant afford them... call up progressive insurance, convince them to lower it.. and u can take all my money for pedals

do you have any sample circuits of photo resistors? why would you say its better than a photo transistor?  if u look on my expresion pedal dream post deal... im having this argument in my head there too... and the photo thing seems to be the easiest to DIY... but it seems like again it could have its limitations... for me the problem was switching using multiple pots and multipe wah/ volume/ pan type circuits

i understand how they mechanically work... use a V strip.. more light, more resistance, less light, less.. easy.. but how do you wire that up? is it basically just like a pot? so itd be like...( for a standard wah.. i can make it more difficult with my whole switching deal myself..)

guitar signal in - switching.. all the standard.. then once the wah circuit would goto the pot to go WAH WAH WAH... 8-)... instead it would use like a relay to turn on the power to an infra-red LED... and a photo reciever.. i guess thats called the photo resistor (so it makes more resistance with more light..)... and then the signal would go thru the photo resister as if it were running through an "adjustable resister" aka pot?!??!?!? did i just figure it out!?!?!? wooo!

lookng at ur effects it seems like uve dealt with these before.. have any trouble mechanically hooking it all up?

[zachary vex]

i've never used interruptors, but you can cut apart a vactrol if necessary to make one.

[birt]

i would always suggest working with photoresistive cells rather than phototransistors for audio circuits.

i know, but these would be used as variable resistance to ground. not really in the signal path itself.. i mean transistors are used as variable resistance to ground in loads of modulation circuits, the envelope of the dr quack for example right?

[col]

I did a post a couple of weeks ago but I don't know how to link to it. Have a search, there are some results of a simple experiment I did with an optocoupler. I have since used a couple with success and find them easier to use than a LED/LDR combo.

Col

[birt]

I did a post a couple of weeks ago but I don't know how to link to it. Have a search, there are some results of a simple experiment I did with an optocoupler. I have since used a couple with success and find them easier to use than a LED/LDR combo.

Col

nice. i'll do something like that with the ilct6.



edit: just found out i lost that ic. so i guess i'll have to wait until i can get another one.