Using triac and optocouplers instead of relays?

You can buy relay boards on eBay fairly cheaply.

Search for something like "Arduino relay" and you get a fair number of choices. A board with a single relay for buy-it-now is less than 3 bucks, you then add the cord yourself to get what looks similar to the powerSwitchTail that you linked to.

So as long as you're comfortable (and safe) working with the higher voltages, that's an inexpensive solution.

This is something I intend to do for my greenhouse, to power a water pump. I bought a 2-relay board recently, I think it was about $4.

You can go totally inexpensive by using just the relay, but buying the board saves you a LOT of trouble for the extra couple of dollars.

Cheers,

-Nico

Right now I am using directly a vacuostat switch. It combines the best of a relay and a vaccuum control but also the worse, it is expensive, tricky to set and it wont last a lot.

Going with arduino + vaccuum sensor + relay is more expensive but nearly as expensive as arduino + vaccuum sensor + triac, the latest is not suppose to stick at un unknown time. My use is between 8hours to one day and depending on the vaccuum bag quality I will go between around 100 (very good) on/off to 10000 activations. Changing the relay each time would be an option but still I dont like it.

So my question for the high_voltage was more on what king of triac do you recommend...

For the high current well it would be too much current for relays... minimum 55W by output.

Edit: Doing more research, it looks like Solid State Relay (SSR) are packaged triac like a relay. I may try that first...

http://www.mpja.com/3A-480VAC-Solid-State-Relay/productinfo/18194+RL/

Hi loopingz,

I was just about to ask you if the solid state relays are similar/same/different to the triacs, then I read your edit

From what I've read they switch faster and last longer. Boards with solid state relays all set up neatly are also available relatively inexpensively on eBay (hmm, I may have an eBay addiction ).

Unfortunately I don't know much about triacs, and most of the stuff I do is hobby related, so I can't give a proper real-life-based recommendation, sorry.

Cheers,

-Nico

I would probably go with the SSR you linked, as it includes optoisolation in the package. Second option would be to use optocoupler and triac, and relays I really would not consider due to poor perfomance in switching time, lifetime and RF noise from sparking contacts...

There are plenty of good opto couplers with a triac output, which can be used to drive a high current triac, I can post a few examples here if you wish. Just be careful with the mains side!!!

Solid state relays are another way to go as they combine opto isolation and high current drive, also developement time will be slightly shortened as you can usually just hard wire them instead of needing a PCB, as they have screw terminals (at least the ones I have used did!). But a lot more expensive....

Best of luck and keep us up to date with your venture.

regards

Andy

There are nice one-piece optically isolated SSR's like this, too:

http://arduino-direct.com/sunshop/index.php?l=product_detail&p=216

DISCLAIMER: Mentioned stuff from my own shop...!!

If you are looking to use triacs and optoisolators instead of relays then this site might help you:

http://doityourselfchristmas.com/wiki/index.php?title=Electronics_Hardware

The Do It Yourself Christmas Web site offers lots of ideas of how to control lights using a processor, but the benefit of the technical knowledge there goes beyond just "Chrstmas lights". You might have to explore the above noted link, but you'll find plenty of prebuilt hardware that can easily be controlled by an Arduino. Good luck with your project! Salvador

Hi Terry,

I really like your website! I was actually looking at it yesterday when a search for coding information for the nrf24l01 wireless boards led me there.

I'm also pleasantly surprised by your excellent pricing, so I've bookmarked it

Thanks for all the great information you provide there, it's very much appreciated!

Cheers,

-Nico

Hello,

Actualy you may prefer solid state relay's as opposed to opto coupler and triac.

Opto couplers & triac will switch on the power as soon as it receives the signal, which may not be desirable if the line voltage is at it'peek as this will create some heavy surge current through the load, triac and wiring.

On the other hand solid state relays has build in cuircuitry thet detect the load voltage and wait till it cross the zero threshold. thus avoiding a current surge.

here is one cheap version on ebay

http://www.ebay.ca/itm/3-32V-DC-Input-24-380-AC-Output-Solid-State-Relay-25A-/260981274891?pt=LH_DefaultDomain_0&hash=item3cc3b2390b

it will accept any input from 3v to 32v to activate and loads up to 380 volts ac , heat sink included