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problems with optoisolator-triacs

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pumpkinman

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i am working on a project for an EL wire sequencer that will be controlled with a microcontroller. my initial design simply used triacs (511-Z0103MA on mouser) in series with the the EL wire and an AC source (120Vp at about 1kHz). the gate was connected to a resistor and then to the microcontroller output (actually, this was simply a DC power supply for testing). this design worked just fine - when i switched the gate to 5V the EL wire lit up and when i dropped it back down to 0V it switched off.

however, i decided to switch to optoisolator triacs (MOC3022 from TI) to protect the microcontroller i would be using. i pretty much kept the same set up as before with the DC source in series with a resistor and the optoisolator's internal LED, and the triac terminals in series with the AC source and the EL wire. the EL wire turns on as before, but when i drop the input voltage back to 0V, the EL wire remains on.

i have been reading various forums looking for similar issues and tried the "snubber" circuit mentioned by some with no effect. what could be the issue (and possible solution) to my problem?
 

you must connect the moc between the gachette and the A2 (or MT2) pin of the triac
otherwise it doesnt work...
written nowhere, but if you look at schematics on the web, they are always connected like this.
regards,
 

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If you are still using DC on the triac side of the opto-triac, it is likely that the inernal triac is latching on, Regards, Orson Cart.
 

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