Oven Oops Timer

I built a device that will:

1. Let you set a normal timer for your food when you put it in the oven
2. Tell you after the fact if you left the oven on when you took your food out of the oven.

It's inspiration came from my roommate leaving the oven on a few too many times when her food was done.

It is designed to match the stainless steel aesthetic many kitchen appliances have in order to fit in within the space. It has symbols etched onto the front for understanding as well as a hook attached there so it can fit on the handle of your oven.

There are photos and videos attached to nearly every step.

Iteration 1:

• Arduino Mega
• Breadboard
• Jumper Wires
• 4 Digit Segment Display
• LED
• 1K Ohm Resistor
• Buttons
• Buzzer
• Heat Sensor

Iteration 2:

• Arduino Uno
• Breadboard
• Solderable Breadboard
• Jumper Wires
• LCD Display
• Potentiometer
• Neopixels
• IR Remote
• IR Receiver
• Buzzer
• Heat Sensor

1. First thing I did was make the timer with buzzer via this link
2. Once I got the timer working I added the LED to flash when the timer was done
3. With the LED, was the heat sensor. The LED would light up when the heart sensor found a temperature greater than the set heat variable.

For my second iteration I decided to upgrade aspects of the first iteration to make it neater and more self-explanatory. For example, my plans were to:

1. make the buttons controls into remote presses
2. start/play button
3. reset time button
4. all numbers corresponding to setting time
5. throughout the process I decided to change the 4 digit segment display into a LCD display
6. i did this because it was proving very difficult to control the all the different segments with a remote, and there was already documentation out there on a remote controlled LCD timer.
7. make the buzzer into an mp3
8. change the LED into neopixels with more controls, such as:
9. Flash at both timers ending
10. Have their base (when its not a timer) show the current temperature via dynamic changes

I succeeded in everything except the mp3 where I decided to stick with the buzzer.

My first step was the get the mp3 working:

• I got the mp3 working with a sound that said "You left the oven on" only once.
• I never changed anything, but the speaker connections were very finicky
• I ended up scrapping the idea of the mp3 due to the finicky speaker connections and knowing the buzzer fit with the aesthetic of the purpose more.

Getting the Neopixels to light up:

• I first got myself familiarized with them and lighting them up in different colors.
• Then I got them to light up based on being within a certain increment of temperature since my heat sensor set up stayed the same as the first iteration.
• Then lastly, for my project purposes, I got them to light up dynamically based on temperature, which is shown in the attached videos.
• 1. When they are blue for cold/oven not on
• 2. When it is hot they a certain number or neopixels turn on to indicate heat as it gets hotter, and turn off as it cools down.

After the Neopixels I started on getting the on the timer:

• After a lot of struggling related to connecting the remote to the segment displaus, I found this resource for a remote controlled timer where I adjusted it to get rid of the LED and second potentiometer controls.
• I got the timer working for setting second with the remote. I set my own choice of buttons on the remote to certain controls like start, numbers, and reset. The reset button would only work once on the times up screen and if you put in wrong number on the start screen. Due to code complications I was not able to make it so you could reset while the timer was going.
• The timer source came with the buzzer so I connected that to my board.

At this point all the circuitry was done and it was all about getting the code to work:

• The code for the Neopixels and the LCD was all set up as I was able to figure it out and get it from other sources and the heat sensor was the same as my previous iteration.
• The issues that started arising were getting the timer to wait 30 minutes (or any chosen time) after the buzzer went off and check for heat. Additionally, after the timer went off and the "Time's Up" screen came on the remote controls would not work to get back to the starting screen.
• I also was finally able to get my code/circuit to wait 30 minutes (or desired time) before checking if there is heat and executing that code.

The next step I did was taking all my circuit pieces and solder them onto a protoboard:

• I did all of my wires and additional pieces like LCD, heat sensor, buzzer, etc.
• Once soldered, the only the not working was the LCD, so I went through every connection with a multimeter and found one of the display pins was not fully attached to the protoboard so I re-sodlered it and it all worked.

After all of the circuitry was done I started more on my enclosure:

• I decided to make an acrylic box and spray paint silver in order to try and match the stainless steel kitchen aesthetic.
• I etched a thermometer and a fire symbol on their side of the temperature indicator lights in order to attempt to make the purpose a little clearer.
• I added a cutout on the front for the display and a circle on the side for the cord.

My final step was to put everything together:

• I hot glued the display into its cutout with the Arduino command stripped to the back of the protoboard.
• I hot glued the handle to the back of the box.
• Due to the potentiometer and not always knowing what the contrast of the LCD will be when turned on I added hinges in order to be able to open it up and adjust if needed. This came in handy for when I needed to upload new code to the board for different temperature settings.

At the end of this project it was able to do most everything I set out for it to due.

• Lit up red dynamically based on rising temperature and blue when cold/oven not in use
• Set a timer for your food
• Wait 30 minutes after you food and alert you if left your oven on

Things I encountered:

• I accidentally insulated my heat sensor inside my enclosure so in a real test it would not be able to test the heat very well outside of the acrylic. In order to show the demo I had to open up the back and point the heat gun right at the heat sensor, and also adjust the temperature and oven on parameters via the code to show different qualities.
• When trying to make my enclosure look nicer after the glue messing it up, all the paint started peeling off night before the presentation so I had to put it all back together after repainting it.
• The temperature indicator code was so big/took so much time that for a while it make my code never get to my remote receiver and so for a while I could not figure out why my remote stopped working.
• Of course there are probably many more but these are the biggest issues I ran into.

Overall, I am very proud of this result for it being my first time experimenting with circuitry and also my first time learning 3D printing and laser cutting machines and software.

Attached is a video of it front start to finish of all the remote functions, the timer going off for your food, the secondary timer going off letting you know the oven has been left on, and reseting it. (it is sped up and lower quality in order to get the file small enough to put in)