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Using triac and optocouplers instead of relays?

Former Member

  Hi there,

 

 

First post, short presentation.

I am mechanical engineer but I have been always interested in electronic. I have been building myself a couple of device, most of the time because I had needs for stuff not yet available or affordable (fast charge nimh, DC-DC Car to 5V 3A, vaccuum regulation...). I have (nearly) never been twaeaking a microcontroler so far, I mean my temperature regulator has been built by a friend!

I think Arduino stuff is brillant and I am looking forward doing some simple stuff to start. It will be mainly to help produce my kite boards (Temperature and vaccuum regulation, but why not a CNC or a laser too?). If I am doing great I also have an old project: build a multy channel accumalator capicator (plotting V over time doing a constant discharge), to check their real capacity, internal resistance pair them and trash the bad ones!

 

 

I am looking for using an Arduino to pilot high voltage device. For exemple a fridge pump (=vaccuum) which draws about 100W or so at 230V. My application would require a lot of shutdown/poweron so I would prefer not to use relays.

I have seen the following online http://powerswitchtail.com/PSTIIU.aspx

Except from learning is there any reason for me to build something similar or should I go directly with that? I mean shipping+ adding the plug I will be under $60 for two switch. Do you any kit with 2 or 4 triac output that could do the same? I do not fancy to much playing with high voltage, so I am asking first.

 

 

I also have another project with high current needed. I will pilot with a classical +5V, and I need high wattage on 12V. I will use 12V car light bulbs to produce... heat (between 200 and 300W), which will be safer I think than using 230V light bulbs or heat wire at the same voltage. I am wondering if turning On/Off a computer power supply is OK? I was thinking of using a refresh rate around 0.2 ou 0.3Hz (3s or 5s).

 

 

Thanks for you support.

Parents

  • 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

Reply

  • 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

Children
  • in reply to ntewinkel

    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/

  • in reply to Former Member

    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 image

    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 image).

    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

  • in reply to Former Member

    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...