Which board do I need?

Hello everyone!

I am new here. I am working on a project where I need to be able to set a temperature on a display and then monitor that temperature with a probe. I think I understand how to do this. Once the temperature falls below the allowance (say I set it to 100 degrees F and my tolerance is 5 degrees. once it reaches 95 degrees an action is taken)

Once at the tolerated level, I need to "turn an outlet on."

SO basically I need to figure out how to turn a 220 outlet on and off.

I'm not sure which arduino board suits me best. Also I should add that I need to do two instances of this. Meaning I need to monitor two temps and turn on/off two outlets.

Thanks for any help you may provide.

This is fairly simple to do but if your not sure of the electronics be careful ! mains is less forgiving than a battery or low voltage circuits and electrocuting yourself or someone else would be a BAD thing.

Things to consider is using a relay , this will at least isolate the low voltage arduino end from the high voltage, the only problem with this is if its a large load then you can get horrible switching problems.

Solid state relay could be used as an alternative, or then your into switching the mains with a triac and hopefully a zero voltage switch control circuit (i.e. the Triac is only turned on at the start of a voltage phase rise reducing switching currents etc.)

Having said all this I would seriously find someone that nows this stuff and help you direct as a mistake with the mains could seriously harm someone.

All of the arduino's boards would be able to do temperature measurements and control 2 switching circuits easy.

The main question that will also need to be asked is what is it on mains your turning off and on , what type of load, what current, is it a motor, heater, light, 3amps, 5 amps, 13 amps ? etc. I also take it you mean AC mains when you ask 220, UK = 240, USA 110-120 , different frequency mains too, all this makes the type of circuit you use important. There can even be questions like is it soft start i.e. the voltage / current is slowly raised so as not to shock the circuits etc. sorry not to fill in all the gaps but my knowledge is more towards Software but I have an understanding of the electronics involved too.

Thanks for the replies.

First off, I would like to say that I am running everything by an electrician before attempting anything.Just to be safe.

I basically want to run a heating element like you would use in your hot water heater. And depending on the temperature reading I would like to switch the outlet that the element is plugged in to, on and off.

Is there an outlet with a relay built in?

Any other suggestions?

Thanks!

http://www.sparkfun.com/tutorials/119

I found this tutorial.

I think this is what I need.

Kcarp:
I’m not sure which arduino board suits me best. Also I should add that I need to do two instances of this. Meaning I need to monitor two temps and turn on/off two outlets.

Any Arduino can do that. The Uno is a handy size.

fungus:

Kcarp: I'm not sure which arduino board suits me best. Also I should add that I need to do two instances of this. Meaning I need to monitor two temps and turn on/off two outlets.

Any Arduino can do that. The Uno is a handy size.

Thank you for the reply. I picked up a Uno a few days ago... Loving it more each day. I am learning that I can do a lot more with it than I though. It's just a matter of finding the right components and trying to learn about electronics at the same time. I will hopefully get it all figured out... I am real excited to actually start building my project. Right now I'm just in research mode and making the light blink on the Arduino haha.

If I can get these relay's figured out I will be in good shape to start building.

I found this tutorial.

I think this is what I need.

The tutorial tells you all you need to get them to work, I.E. a little transistor drive circuit, but I really hate the idea of a clunky relay to switch a heating element (ask you friend about a solid state version or to even look at a cross over zero switch at least)

all the best