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Author Topic: 16x2 goes blank after few hours.  (Read 527 times)
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That's not clear to me.
Not wired AND no jumper.
Does that mean that there is only 1 single wire to each optocoupler ?

The jumper should indeed be open.
But there should be a circuit, meaning that both wires to the optocoupler should be used in order to complete that circuit.
I can't see how else the LED inside the optocoupler could be lit else.

A capacitor forms a barrier to DC signals, but is a short to pulses.
That way it can do its filter function which you are using at the moment.
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Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

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That's not clear to me.
Not wired AND no jumper.
Does that mean that there is only 1 single wire to each optocoupler ?

The jumper should indeed be open.
But there should be a circuit, meaning that both wires to the optocoupler should be used in order to complete that circuit.
I can't see how else the LED inside the optocoupler could be lit else.

A capacitor forms a barrier to DC signals, but is a short to pulses.
That way it can do its filter function which you are using at the moment.


Yes ...  nothing on the ground and com pins.  (which can be jumpered)

What you mention makes perfect sense to me, but, am a bit confused that it is working atm.    

 smiley-roll-sweat


edit: I am not near the setup atm, I will take some pictures tomorow.
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I am not near the setup atm, I will take some pictures tomorrow.

That will be interesting.

The point is, you need the optocoupler return line - the one marked "COM" - to go to the Arduino ground in order to drive the opto-couplers.  I am in fact, puzzled that anything worked at all (unless it just happens to be fitted with EL814s which is a very interesting possibility, as these appear to be very cheap on eBay) without that reference connection.
« Last Edit: July 24, 2014, 06:27:13 am by Paul__B » Logged

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Paul: your link results in a 404 message (page not found)  to me.

Google helped with that though.
It is an AC optocoupler, which should also need 2 wires, doesn't it ?
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Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

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Paul: your link results in a 404 message (page not found)  to me.
Fixed - sort of.  The link was from Google, and it worked before, seems Everlight have recently repudiated the product.

I do wish manufacturers would provide datasheets which could be found on Google instead of all the rubbish/ unhelpful "datasheets" sites.

Google helped with that though.
It is an AC optocoupler, which should also need 2 wires, doesn't it ?
My thought was that if for whatever reason (and it does make sense, because it would work with either a common positive or common negative to the group of opto-isolators) they fitted EL814s (originally, a Sharp PC814), then if the common is not connected, pulling one input high and another low would activate both optocouplers.  Not necessarily deliberately, but would explain it apparently working with no common connection.
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