Build a DIY CD Tray Timer with Arduino: Step-by-Step Guide

This project shows how to build a simple CD tray timer that automatically opens or closes a CD/DVD drive tray after a user-set delay. It’s useful for demonstrations, kiosk resets, timed media ejection, or just as a fun hardware-and-code exercise. The design uses an Arduino Nano (or Uno), a small servo motor or a linear actuator, a pushbutton to start/reset the timer, an optional potentiometer to set the delay, and a few basic components.

Parts and tools

Arduino Nano or Uno (or any Arduino-compatible board)
Micro servo (e.g., SG90) or a small 5–6V linear actuator (servo recommended for simplicity)
N-channel MOSFET or small relay (if you use a drive-control mechanism that requires higher current) — not needed for servo approach
Pushbutton (momentary)
10 kΩ resistor (for button pull-down/pull-up)
10 kΩ potentiometer (optional — to adjust timer)
Breadboard and jumper wires
5V power supply (Arduino USB or separate 5V source if using many servos)
Small mechanical linkage (e.g., 3D-printed bracket, zip-tie, or plexiglass arm) to connect servo horn to CD tray
Hot glue, screws, double-sided tape for mounting
Basic tools: screwdriver, pliers, wire stripper

How it works (overview)

A servo is mounted to the CD drive bezel and connected by a small arm to physically push the tray open/closed. The Arduino reads the start button and optional potentiometer (sets delay). When the button is pressed, the Arduino starts a countdown; after the delay it moves the servo to the “eject” or “close” position. The button can cancel or restart the timer.

Safety and notes

Do not force the CD tray; ensure your linkage moves smoothly and does not stress the drive motor.
If using a laptop internal drive, be careful opening the case; prefer external USB drives for ease.
Servos draw current—power from Arduino USB is usually fine for one small servo; use a separate 5V supply if needed.

Wiring diagram (servo approach)

Servo signal → Arduino digital pin D9 (PWM)
Servo Vcc → 5V (Arduino or external 5V)
Servo GND → Arduino GND (common ground if external supply used)
Button → Arduino digital pin D2; other button leg → GND; use internal pull-up or external 10 kΩ to 5V
Potentiometer (optional) → middle pin to A0, left to 5V, right to GND

Arduino sketch

cpp
// CD Tray Timer - Servo version
#include 

Servo trayServo;
const int buttonPin = 2;
const int potPin = A0;// optional delay control
const int servoPin = 9;

int buttonState = HIGH;
int lastButton = HIGH;
unsigned long debounce = 50;
unsigned long lastDebounceTime = 0;

bool timerRunning = false;
unsigned long startTime = 0;
unsigned long delayMs = 10000; // default 10s

// servo angles - adjust to suit your linkage
const int closedPos = 90;   // tray closed resting position
const int openPos = 0;      // tray open position

void setup() {
  pinMode(buttonPin, INPUT_PULLUP);
  trayServo.attach(servoPin);
  trayServo.write(closedPos);
  Serial.begin(9600);
}

void loop() {
  int reading = digitalRead(buttonPin);
  if (reading != lastButton) {
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounce) {
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) { // button pressed (active LOW)
        // start or cancel timer
        if (!timerRunning) {
          // read pot for delay if present
          int potVal = analogRead(potPin);
          // map 0-1023 to 1-120 seconds
          delayMs = map(potVal, 0, 1023, 1000, 120000);
          startTime = millis();
          timerRunning = true;
          Serial.print(“Timer started: “);
          Serial.print(delayMs);
          Serial.println(” ms”);
        } else {
          timerRunning = false;
          trayServo.write(closedPos); // ensure closed
          Serial.println(“Timer cancelled”);
        }
      }
    }
  }
  lastButton = reading;

  if (timerRunning) {
    unsigned long elapsed = millis() - startTime;
    if (elapsed >= delayMs) {
      // toggle tray
      trayServo.write(openPos);
      delay(1000); // allow movement
      // after open, reset state (or close after set time if desired)
      timerRunning = false;
      Serial.println(“Tray opened”);
    }
  }
}

Mechanical mounting

Identify a safe location on the drive bezel where a small linkage can push the tray without obstructing eject mechanism.
Attach the servo to the drive’s side or to the drive bay frame using screws or double-sided tape.
Connect servo horn with a small stiff arm (plastic or metal) to the tray face so movement of the horn pushes/pulls the tray. Aim for ~15–25 mm travel — adjust servo endpoints in code as needed.
Test movement manually before powering the drive: gently move the tray by hand and confirm servo positions won’t bind.

Testing and tuning

Power Arduino and servo, ensure servo moves to closedPos on start.
Press button to start timer; observe that the servo moves to openPos after the set delay.
If tray requires two-stage motion, add intermediate positions and small delays in code.
Adjust closedPos/openPos values to match physical linkage limits.

Variations and improvements

Use a second button to choose open vs. close action.
Add an LCD/OLED to display remaining time.
Replace servo with a small geared DC motor + limit switches for smoother force transfer on larger trays.
Add Wi-Fi (ESP8266/ESP32) and a web UI to set timer remotely.
Use infrared remote or serial commands for control.

Troubleshooting

Servo jitter: ensure stable 5V supply and common ground.
Tray doesn’t move: check linkage alignment and servo torque.
Drive motor stalls: increase servo travel carefully or use gentler mechanical advantage.

If you want, I can provide a 3D-printable bracket design, a version using a relay/DC motor, or an ESP32 web-control sketch next.

Build a DIY CD Tray Timer with Arduino: Step-by-Step Guide