How to Build the Toaster Timer

Hello Everybody,

As you know timers are a very useful tool in the kitchen to ensure foods are prepared properly. However, timers are often boring and plain. To solve this, I designed, printed, and assembled the Toaster Timer to make timing in the kitchen a bit more fun. Just like a real toaster, the Toaster Timer has a lever, but instead of putting the bread down, it is a linear potentiometer that can be used to set a general amount of time for the timer. In the code, you are able set the range of time for the potentiometer. The Toaster Timer also uses two pieces of toast and a buzzer to indicate when time is up. The pieces of toast move up by converting the rotating motion of a servo into linear motion. There is a button to control the start/stop of the timer and an LED to indicate if the toaster in on/off. All of these components are controlled by an Arduino Nano and powered by a 9V battery. I used TinkerCad to model a toaster with precise cutouts for all of the components to sit in. This was quite a complex task due to the tight space inside the toaster to fit many components. After many redesigns and iterations, I was finally able to make a working Toaster Timer that you can now build yourself with the following steps. Be sure to watch the video to get a better sense of how the Toaster Timer works. Just note that in the video I set the timer for only about 15 seconds because the range is 0-1 minutes and I put the lever done about 1/4 of the way. Also, my Toaster Timer’s buzzer is faulty, so it is very hard to hear. Besides that I think it is very cool!

Enjoy!

Note:

Some of the supplies could probably be substituted or skipped if you don't have them, but you may need to edit the model or code to account for the change. Also, if you want to add a component or material, please feel free to edit the model.

Tools/Devices

1. Computer (For Slicing and uploading code.)
2. 3D Printer
3. Cable for Arduino
4. Wire Strippers (A knife could also work.)
5. Hot Glue or Super Glue
6. Pliers
7. Optional: Solder Iron (Twisting the wires might work, but soldering is definitely recommended.)
8. Optional: Philips Head Screw Driver (To secure servo, but glue could also work.)

Materials/Parts

1. Filament (Preferably PLA in grey, black, and brown.)
2. 45mm Linear Potentiometer
3. 12mm Push Button
4. Arduino Nano (Another microcontroller might work, but it needs to be small to be able to fit in the small space.)
5. LED
6. 220 Ohm Resistor
7. Dupont Wires
8. Passive Buzzer
9. Electrical Tape
10. Servo Motor (With the singe lever arm.)
11. 9V Battery
12. 9V Battery Connector
13. Optional: Wire Nuts

Amazon Links

Here are some links to components I found on Amazon that will work with the Toaster Timer. These are not affiliate links.

1. 45mm Linear Potentiometer - https://a.co/d/fEBLavh
2. 12mm Push Button - https://a.co/d/6JYolap
3. Arduino Nano - https://a.co/d/iaqUrQt
4. LED - https://a.co/d/aIolNNs
5. 220 Ohm Resistor - https://a.co/d/2py3EKb
6. Passive Buzzer - https://a.co/d/heGWO4r
7. Servo Motor - https://a.co/d/bZGnQRS

Like I said previously in the introduction, I used TinkerCad for all of the 3D modeling. I started by making a rectangular prism, and then rounded the edges for more of a toaster appearance. I then hollowed out this shape to make space for all of the components. The rest of the process was mainly composed of measuring the components with my caliper and then modeling in spots for them in the toaster.

I wanted to keep this project as simple as possible to follow, which meant limiting the amount of components required. I did not add a spot on the exterior for a switch that completely cuts power to the Arduino. I figured it could be added in the inside or I highly recommend editing my original model to make your own version of the Toaster Timer. You may also wat to try adding different features like allowing the toast to pop up even higher.

The only part that needs supports is the main body piece. Orient it the same way it would sit on a counter and just add supports on the main overhangs. For the bread, I used wood filament because that is the only brown filament I have, so I had to use a larger nozzle size.

Note:

I made some minor changes to a few of the parts after taking the pictures incase you were wondering why the look different. All of the pictures from now on are up to date.

Use pliers to get rid of all of the support material. If you print has a lip where it was on the print platform, I recommend removing that with a knife, so it fits the bottom piece better.

Slide the toast piece into the slots, so the cutouts in the toast are facing away from the front of the toaster. These groves allow the toast to be added without getting blocked by the servo bracket. Once the toast is inserted, it may be a bit loose, but it will be locked in once the servo it added.

Cut off and strip all three wires of the servo. Solder on a female connector to the signal/orange wire of the servo.

Solder on three wires to the linear potentiometer. The positive and negative wires are just stripped on the end and the signal wire has a female connector.

Solder a 220 Ohm resistor onto the positive leg of the LED. Then solder a stripped wire on both legs of the LED.

Note:

In the picture, one leg has a female connector soldered on. I originally planned on controller the LED with the Arduino but later decided to just connect it to power to simplify the code.

Solder a stripped wire on one led of the button. On the leg of the button next to the last, solder a female connector.

On the leg marked positive, solder a female connector. On the other leg, solder a stripped wire.

Use either screws or glue to install the servo into the bracket. Make sure the servo is oriented the same way as the photo. I did not screw the lever arm, but it would not hurt if you did.

Note:

In the picture, the wires for the servo are going down below the servo. I would recommend feeding the, above the servo so there is more space for the 9V battery while snapping on the base.

Slide the potentiometer into the slit. I added to strips of electrical tape on both sides of the potentiometer to tighten the fit. I also used a few drips of glue to secure it in place.

Line the LED up with the hole and use a thin item like a screw driver to push it in place. I did not have to use any glue because the fit was perfect.

The button installs very similarly to the LED. Line up the two notches with the legs of the button. I did not have to use any glue for the button as well.

I added a few drips of glue into the holes of both knobs to secure them onto the components.

Get two more female connector and strip the ends. Gather all of the power wires and one of the female connectors and twist them all together. I used wire nuts because it made the connection more temporary then soldering while also preventing a short circuit. Gather all of the GND wires and the other female connector and twist them all together. By doing this, you have one power cable, one ground cable, and a signal cable for all of the components.

The pictures shows how I put the battery and Arduino onto the base piece. The side with the battery matches up with the servo in the body piece. I used tape to hold down the battery and Arduino. I did not want to add brackets to hold the battery and Arduino incase you decide to use a different microcontroller and power source. Plug the power and ground from the previous step into the 5V and GND pins of the Arduino. Then connect the potentiometer to A2, the button to D12, the buzzer to D10, and the servo to D9. Also, make sure your 9V connector has two female connectors attached.

Upload the code below to your Arduino. Like I mentioned in the introduction, you are able to adjust the minimum and maximum times to suit your needs. Once the code is uploaded, unplug the cable from the Arduino. To power the toaster, connect the female connectors of the battery to VIN and GND of the Arduino. I didn’t add a power switch to simplify the build, but it would be helpful to add one on the outside of the Toaster. Lastly, snap the body onto the base.

Code:

#include <Servo.h>

const int potPin = A2; // Potentiometer on pin A2

const int buttonPin = 12; // Button on pin 12

const int buzzerPin = 10; // Buzzer on pin 10

const int servoPin = 9; // Servo on pin 9

const int minTime = 0; // Minimum Time (Adjust)

const int inputMaxTime = 1; // Maximum Time (Adjust)

const int maxTimeInSeconds = (inputMaxTime + 2) * 60; // Convert to seconds

Servo myServo;

int timeRemaining = 0;

bool timerRunning = false;

unsigned long buzzerStartTime = 0;

bool buzzerActive = false;

unsigned long buttonPressTime = 0;

bool buttonPressed = false;

void setup() {

pinMode(buttonPin, INPUT_PULLUP);

pinMode(buzzerPin, OUTPUT);

myServo.attach(servoPin);

myServo.write(90);

}

void loop() {

int potValue = analogRead(potPin);

int selectedTime = map(potValue, 0, 1023, minTime, maxTimeInSeconds);

if (digitalRead(buttonPin) == LOW) {

if (!buttonPressed) {

buttonPressed = true;

if (!timerRunning) {

startTimer(selectedTime);

} else {

stopTimer();

}

}

} else {

buttonPressed = false;

}

if (timerRunning) {

timeRemaining--;

if (timeRemaining <= 0) {

timerFinished();

}

}

if (buzzerActive && millis() - buzzerStartTime >= 10000) {

noTone(buzzerPin);

buzzerActive = false;

}

delay(1000);

}

void startTimer(int time) {

timeRemaining = time;

timerRunning = true;

myServo.write(0);

}

void stopTimer() {

timerRunning = false;

noTone(buzzerPin);

myServo.write(90); //

}

void timerFinished() {

timerRunning = false;

buzzerActive = true;

buzzerStartTime = millis();

tone(buzzerPin, 1000);

myServo.write(90);

}

I hope you enjoyed building/reading along with the Toaster Timer. I think it would be useful for cooking pasta and other foods that don’t require a very precise time. As always, please let me know if you have any questions or comments.

Thanks!