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  • Author Author: a_davis_22
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Automatic Dough Shaper - Blog #10 More Magic Smoke

a_davis_22

Well, as they say, "experience is the best teacher."

 

I decided to work on getting the oven control working since that seemed like it should be pretty straightforward. I had already gotten my mains power switching circuit to work by turning on a lamp. So all I needed to do was write a python program to turn on the toaster oven for about 6 minutes (until it was at 350 F) and then repeatedly stay on for 12 seconds and turn off for 10 seconds. I hooked up the wires, wrote the code, and voila!  Nothing happened. So I trouble-shooted everything! I checked my wiring, I fixed my code, I tried turning on a lamp instead of the toaster oven, I changed wiring, I checked voltages, etc. After several hours I came to the conclusion that my MOC3010 must have burnt up. I couldn't see any possible way, but there was power on the raspberry pi side and no power on the mains power side. At that moment I realized that one of my plugs actually has 3A fuses! I opened it up and sure enough the fuse was blown. After replacing the fuse I turned it on and everything worked! For about 1 second. The fuse was blown again. I figured my toaster oven was just trying to pull more current, so I switched the plug to one without fuses. This time it actually worked! with smoke... I had burned up my BT136 triac. Finally I checked the ratings on the BT136 and my toaster oven. Theoretically I knew that the triac would have to withstand more current than the toaster oven could pull, but in physically creating the circuit I had forgotten. My toaster oven was rated at 12A and the BT136 can only handle 4A. So now I understand that I have to build my circuit with appropriately rated components.

 

After spending an entire day getting nowhere, and being so close to the deadline for this competition, I decided I'll have to drop the toaster oven control functionality. The toaster oven can do it's own temperature control well enough, I just wanted my machine to turn it on and off when it was needed.

 

It will be a miracle if I can get this project finished by Friday.

Parents

  • Project are full of challenges (and potential to create smoke) and your project seems no different.  You comprise to skip the temperature control seems like a very good one given the amount of time left.  It was a great effort to try to control the toaster, and it did give you opportunities to learn, so don't consider it a waste.

     

    Good luck!

    Gene

Comment

  • Project are full of challenges (and potential to create smoke) and your project seems no different.  You comprise to skip the temperature control seems like a very good one given the amount of time left.  It was a great effort to try to control the toaster, and it did give you opportunities to learn, so don't consider it a waste.

     

    Good luck!

    Gene

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