Hi all!
I have to control a small asynchronous mechanical timer that runs on 240v with a arduino. I basically need a relay of some sort to enable the timer. Because of space requirements, a mechanical relay will not fit, as for a triac with optocoupler. Since a optocoupler is a sort of triac, could I use that to drive the motor directly? It's a <3w motor, so it only sources about 0.02 amps. Could this work? Or do you guys suggest another aproach?
Kind regards,
Rens
Most drivers specify they are not suitable for that. And especially with inductive loads like a motor.
Although I do like a Triac, do note there are tiny relays as well. And, especially because the load you want to drive is so low, this might be a lot easier then driving a triac.
Since a optocoupler is a sort of triac
The [u]MOC3043[/u] (and similar) are basically TRIACs and they have an "Absolute Maximum peak repetitive surge current" of 1A, so that would be worth a try.
A "regular" opti-isolator has a phototransistor so it doesn't work on AC.
I should say that as well but from the datasheet:
Note:
This optoisolator should not be used to drive a load
directly. It is intended to be a trigger device only.
Thanks for your replies!
I also looked at the moc30xx opticouplers, and also read that they should not be used to drive a load. Tiny relays are quite expensive, I am looking for something <20 cents bulk.
The MOC3043 is designed to drive a triac. Arduino -> MOC3043 ->Triac -> Load. Do you have space for the 6 pin MOC3043 and a TO-92 Triac?
20 cents is quite tight indeed. Also for a triac, because with a motor you can't leaf out the snubber!
And do note, with something like a MAC97A6 and a 3W motor you are borderline with the holding current...
3W is small enough. Just ignore the "do not drive a load" instruction. It would not be a question if it was a 3W relay coil you were driving.
With so small a motor you probably also don't need snubber.
Thanks all! I think I am just gonna order a few of the moc3021 and see if it will work.