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I am trying to make an automatic garden gate unlock that runs on a timer. I plan on running an arduino uno 24/7 with a software timer that activates a motor to release a bolt lock. I am going to fit all the electronics and extension cord into a waterproof junction box. Will this cause over heating? Is there a need for some kind of waterproof cooling system? Has anyone ever built outdoor electronics and ran into this problem?

MyDisplayName
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2 Answers2

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The linear regulator on an Arduino works by converting excess voltage to heat. If you power it with 12V and draw a full amp from it it will turn (12-5)*1a or 7 watts of power to heat, and quickly overheat even if it's not in a box.

If you power it from 6.5V and only draw 300mA from it, it will turn (6.5-5)*.3, or a little under half-a-watt. While the Arduino is idling it will probably only draw 50mA, so less than 1/10th of a watt of heat.

For infrequent, short bursts of a few seconds you can probably get away with drawing 500mA of power without overheating.

Or skip the internal regulator and use a buck style voltage regulator. Those generate a LOT less heat.

Edit:

For a project I did recently, I used an external 5V regulated supply for everything. I cut a USB cable and soldered the red and black (+5V and ground) to the 5V supply, and plugged that into the Arudino's USB connector. That feeds 5V into the Arduino.

Duncan C
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The simplest selection is Aluminum water proof box.

You can make it yourself, using aluminum U profiles, and mount arduino heat generator parts on the internal surface of the box.

Saeed Mirshams
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