SparkFun Forums

[raygeeknyc]

Hi all
I'm working on a project to animate a Electroluminescent display elements using a Microcontroller (in it's final form probably some Atmel chip, but an Arduino for now).

The EL wire requires high voltage AC - I've got a range inverters that drive the wire of different lengths and at different brightnesses using anywhere from 30VAC to 160VAC.

I want to switch this AC using the digital output pins of my microcontroller - I've looked at a transistor based optocoupler - specifically a PS2501 but have learned that transistors can't be used to switch AC, hence optocouplers like this one are unsuitable.

Can anyone point me at or describe a recommended method of switching such AC from microcontroller level signals?

Thanks
---Raymond

[Stevetronics]

Look into triacs. See the sparkfun tutorial: http://www.sparkfun.com/commerce/tutori ... als_id=130
You'll have to make sure that your triac can handle the power, but even a small TO-95 package like the SFE guys use in the original proto looks to handle it fine.

[esklar81]

Raymond,
You haven't given us any idea of at what speed you need to switch EL elements on and off. If it's at the sort of speed you need to produce "moving" images (> 15 Hz), then solid state switching is probably your best bet.

The EL wire requires high voltage AC - I've got a range inverters that drive the wire of different lengths and at different brightnesses using anywhere from 30VAC to 160VAC.

Have you considered switching the inverters on and off? This could be anything from a good, cheap solution to a recipe for poor performance and frequent inverter replacement. Where it falls in the spectrum depends on the hardware and the switching frequency.

If you're looking for much slower switching, (<< 1Hz, as is used in "old-fashioned" neon signage), you might consider relays. This is probably not an approach that will provide you much value at relatively low power, but something worth keeping in mind.

I want to switch this AC using the digital output pins of my microcontroller.... Can anyone point me at or describe a recommended method of switching such AC from microcontroller level signals?

Lastly, depending on the control signal you need to send to your switching device, you may yet have an opportunity to use optocouplers. If the control signal you need to send to your switching device is outside the range of the Arduino, an optocoupler is a good means of stepping up power in one direction and providing protection from feedback in the reverse. Electromechanical power switching (relays and contactors) is a "harsh" world from the microcontroller viewpoint.

Good Luck,
Eric

[raygeeknyc]

Hi all
Thanks for the replies - I apologize for the lack of detail in my post.

I am switching at 2hZ - so there's little or no constraints imposed by switching rate.

Relays looked to be larger than I can easily fit in my project -both for the need to isolate them with another layer and for physical size.

Triacs look to do the trick (almost a rhyme there ) and that project referenced is similar enough to mine to make it a good reference.

Thanks again
---Raymond

[MendingThings]

Triacs should work fine. Good luck.