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Will 5v to the ground... EE help with RGB Topfire... see post #22

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Bender:
OK lets go the opto-isolator route

what kind, and what size resistor would I need for that circuit

DaOld Man:
Well I would use a til119 opto isolator, just because I happen to have a few extras.
The resistor for this baby (at 5 volts) would be around 300 ohms.
The led of the til119 is good for 20 ma easy, so, E/I=R or 5/0.020 = 250 ohms, but  250 to 330 will work just fine.

Edit:
 I forgot to  account for led voltage drop, which is around 2 volts, so formula for resistor would be 5-2/0.020 = 150,
so better make it a max 200 ohm resistor.

Bender:


After I saw a picture of something similar I messed around and came up with this and it works, How come? :dizzy:
Am I going to fry anything?

EDIT: OK... not so fast seems like I fried the Red LED, oh well worked for a few minutes :-\

DaOld Man:
I dont know, I dont see how it is working, unless the two devices have isolated grounds. maybe??
I mean, I see how the mini pac is getting its button fired, but whats going to happen when the ledwiz turns on the red wire going to the led and the button is pressed at same time?
But if it works, what can I say?

Bender:
well it doesn't work, I fried the red LED the one the button was hooked to, coincidence I think not

opto-isolator to the rescue...

I need to learn some patience :-[

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