Picture of Temperature-controlled USB fan @MilCandy
As summer is coming, I bought a USB fan from HuaQiangBei, Shenzhen. However, when I focus myself on work(or game), I could hardly notice its existence. If I can teach it how to think and execute its duty without my order, that will be more practical and fun! So roll your sleeves and follow me to refit a temp-controlled fan!            
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Step 1:

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The structure of USB fan is pretty simple. When you break it down(or even you don't need to, just think in your mind), you can find it just consists of a motor and a key. To make it controllable, turn it over,  screw out the screws then we can continue to the next step.

Step 2: Solder the controlling wires

Picture of solder the controlling wires
First of all, you need two wires. Then solder them on two ends of the key. It doesn't matter which side is positive and which side is negative. They function in the same way.

Step 3: Wire up the Relay

Picture of Wire up the Relay
Grove - Relay has two terminals for connecting open wires. Put 

Step 4: Combine the stuff

Picture of Combine the stuff
The temperature sensor, relay board and MilCandy are all members of Grove plug-and-play system. In this step, find two Grove cables to connect all the stuff. The "eye" of the MilCandy, AKA temperature sensor, should be connected to the input side of MilCandy. And the "hand", AKA relay, should be connected to the output side of it. Then they are ready to go.

Step 5: Teach MilCandy your IFTTT logic

Picture of Teach MilCandy your IFTTT logic
To teach MilCandy your logic, you need to know how it works.Double click means trigger point to MilCandy. And single click means "one this side of trigger point, I can take a rest for a while". Then once input value from the sensor meets conditions you set, the actuator connected to the output end will run, like in image 2.  

Step 6: Done

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Now! MilCandy can serve you by itself! I used the combination of Grove - Temperature sensor, MilCandy, and Grove - Relay to implement this mini-project. But we have so many input sensors and output actuators. If you have an interesting idea, make a comment below and share with me.

Do you have any idea on to adopt this for a commercial desk fan(about 60W)? I'm trying to look for some circuits but they are too complicated...

Well my idea is to utilize the 3 speed control of a regular desk fan.. then at certain temperatures it will be switch on 1, 2, and 3, as temperature increases. Something like that

litliao2 years ago
@angpal59 So sorry for your confusion. The Seeedstudio account is not tied up with mine. I replied your question with that account yesterday. Did you receive it?
Jayefuu2 years ago
seeedstudio: A visitor to the site is asking a question about your project in Answers. Perhaps you'd be able to help them out?

the-new-x3 years ago
And the source code is?
no need source code. The MilCandy is pre-programmed when shipped. So just need a few clicks to kick off a mini project. if you mean the firmware, try more info on Seeed Studio website, where you can find the open source file. :)