tomcody Posted September 21, 2008 Report Share Posted September 21, 2008 Hi everybody, in my country the 6n138/139 optocoupler is a little expensive and some times a hard to find component, and searching in the web I found an alternative circuit with the 4n26 or 4n36 (I tested it with both) - comes in PDIP-6 and this is the equivalent circuit for using instead of 6n138/139:I'm not sure but if you look at the fairchild datasheet appears a lot of others optocouplers - maybe those works too. Quote Link to comment Share on other sites More sharing options...
rasteri Posted September 22, 2008 Report Share Posted September 22, 2008 I use a 4n25, since that's the only optocoupler my local Maplin had. Never had any problems with it. Quote Link to comment Share on other sites More sharing options...
stryd_one Posted September 23, 2008 Report Share Posted September 23, 2008 Is there meant to be a pic there?Edit: I forgot I can see source of posts hehe the original link is:http://img300.imageshack.us/img300/5084/circuitoconel4n26o4n36hm2.gifI guess imagesHack is being lame with referrers...Rasteri are you using the 4n25 as a drop-in replacement or what? Quote Link to comment Share on other sites More sharing options...
rasteri Posted September 23, 2008 Report Share Posted September 23, 2008 Rasteri are you using the 4n25 as a drop-in replacement or what?Unfortunately not - the pinouts completely different (for a start there's two less...) I've attached the circuit I'm using, I dunno if it's an optimal solution but it certainly works.EDIT : My schematic was wrong, LyleHaze's is better (see below) Quote Link to comment Share on other sites More sharing options...
lylehaze Posted September 23, 2008 Report Share Posted September 23, 2008 Your pin numbers have 4 and 6 swapped.This might confuse somebody that tries to wire this up.This one has them corrected.Also, this circuit should have a pullup resistor forpin 5 (to RX). It might work without it, but for theprice of a resistor, why take chances?Have Fun,LyleHaze Quote Link to comment Share on other sites More sharing options...
tomcody Posted September 24, 2008 Author Report Share Posted September 24, 2008 fixed it, now are correct - I tried before a simple circuit like yours, but it doesn't works, I'll try your circuit. Thanks. Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted September 24, 2008 Report Share Posted September 24, 2008 *ahem* cross post.very useful, though. ;D Quote Link to comment Share on other sites More sharing options...
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