Shopping list.

Hi all, first off I'd like to say what a great forum this is! There's obviously a lot of knowledgeable people on here, who hopefully will make my Arduino journey a relatively painless one.

I'm planning a little project to control a gas fired oven, which has three states, off, low and high. What I want is to be able to set a temperature and a time, and let the Arduino control the burner. So my plan is to use a K type thermocouple, coupled to an analogue i/p via an amplifier (AD595), with temp and time settings being programmed via pushbuttons, and an LCD display to give readouts/adjust setpoints. I have the following as my shopping list.

Arduino Duemilanove
K type thermocouple
AD595 Amp
pushbuttons
LCD display (something reasonably simple - 4x20 etc)
2 x relays for the 240v burner control.

Is there anything obvious I've missed, or maybe someone thinks there's a better way to do it?

Sorry if I've posted in the wrong section, this one just seemed to be the most appropriate.

Thanks in advance, E.

unrelated, but it reminds me of a thermocouple project of mine. The idea was to have a small cage inside a grill, and based on the temperature it would rotate my hamburger for me using a servo. I could never get the cage worked out though.
I don't know how your oven works, but the project looks good to me.

Fire extinguisher?

If you're going to control relays you're going to want protection diodes.

Get some random resistors, including a potentiometer to adjust LCD contrast.

Make sure you get the components the AD595 needs.

Consider perhaps using fuses in the circuit.

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, light sensor, potentiometers, pushbuttons

Thanks for the replies.

A fire extinguisher isn't a consideration, there's nothing in place to make it feasible. It's an industrial burner, I'm just trying to improve the existing control system (the main priority is the inclusion of a timer for auto shut-off).

I'll look into the diodes, but I was planning on using "off the shelf" arduino compatible relays (such as the ones found on ebay based around an Omron) - I figured it would be easier and plug and play?

I'll get a handful of resistors etc. too - and fuses is a good idea, thanks.

One other thing I'm considering - would I be better to use a RTC for timing purposes, or would it be overkill? The only timing would be for the oven's cure cycle (15 mins), and possibly a cumulative timer for burner on high/low.

Thanks again, I always find someone else will see something that I haven't.

Relays generally contain no diode and need more current than an Arduino can deliver.

I you want it more convenient, you have to pay for it!

When talking of microcontroller compatible relays, I only know of Reed Relays, they optionally(!) come with an integrated diode. Their max current is 1A generally. Omron might be one manufacturer.

An RTC is needed if you need ABSOLUTE time.

Thanks for that. I've had a look around and realised (as you have said) that there's no relay easily available that I could use which can be directly driven from the Arduino, so I'll cobble together a arduino/relay interface. This way I'll know for sure what I've got and I'll learn a bit more about why it does what it does.

On to the shopping list proper and schematics now!

I love this forum!

Add parts for a watchdog circuit. Something which cuts the power when the arduino doesn't control the oven any more because of a programming error or something else going wrong.