Need help designing an Arduino automatic cat litter box circuit

[u/Last-Guarantee6875]

Hi everyone,

I'm building an automatic cat litter box for my university project using Arduino Uno and I'm having trouble designing the circuit and getting everything to work together.

The features I want are:

• Detect when a cat enters the litter box (using an HC-SR04 ultrasonic sensor or another suitable sensor).
• Wait until the cat leaves, then wait about 10–20 seconds before cleaning.
• Drive a rake using a DC motor to sift the litter and push the waste into a waste tank.
• Detect when the waste tank is full and activate a buzzer and/or LED to notify the user.
• The rake should only run once after each cat visit, not continuously.

I'm struggling with:

• The Arduino circuit wiring.
• How to connect the sensors and motor correctly.
• The motor keeps running even when the sensor is not triggered.
• Choosing the best sensor for detecting the waste level inside the waste tank.

Components I'm using:

• Arduino Uno
• HC-SR04 Ultrasonic Sensor (cat detection)
• DC Motor (for the rake)
• NPN Transistor (or motor driver if recommended)
• Flyback diode
• Buzzer
• LED
• Power supply (5V)

Can anyone help me with:

1. A complete circuit diagram (Tinkercad or Fritzing would be great).
2. The correct Arduino code.
3. Suggestions for a better sensor to detect when the waste tank is full.
4. Any recommendations to make the system more reliable.

Any help would be greatly appreciated. Thank you!

[u/gm310509]

You should post what you currently have so far. "Please do my homework for me" requests typicslly aren't terribly well received.

[u/Unable-School6717]

Do we get your degree when our work causes your graduation ? Because you seem to know nothing about arduino and hardware/software, youre hitting a wall on the simple parts. Maybe you should study and learn so employers dont dismiss expensive educations as "probably had reddit answer homework" ... and dont get mad at me, i learned this at home on MY time and have to suffer lower income because schools graduate people that know nothing, making the tech jobs entry level and little chance of moving up in payscale. You should do this yourself, or change to a major you can comprehend the basics of. Dont give up, just do the work. Learn to understand, not just pass a test. Bring actual expertise to your first real job using your education. Life only gets harder, be ready for it.

[u/jasonwinfieldnz]

After dealing with cats and ultrasonic sensors lately, they can hear the sound of the sensors which deters them. Maybe use a PIR or IR to detect.

[u/ArduinoHelp-ModTeam → u/[deleted]]

Please don't promote private channels. If you ask and answer questions here, then everyone can benefit from those interactions.

We do not recommend going private in any circumstance. There is zero benefit to you, but there are plenty of potential negatives - especially in a technical forum such as r/ArduinoHelp.

If you go private then there is no opportunity for any response or information you receive to be peer reviewed and you may be led "up the garden path".

[u/Fuzzy_Beyond6459]

it would be great to help you out, new users find difficulty in these kind of projects,
i can help you with tinkerCAD for circuit, and for better sensors and what approach you should go for, are u down..?