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Toy Joy (Smart 3-Digit Place Value Vault & Safe Locker)

Source:

Build a wooden toy safe box with a 3-digit rotary encoder dial panel (Hundreds, Tens, Ones). Enter the target 3-digit code (e.g. 348 = 3 Hundreds + 4 Tens + 8 Ones) to unlock the servo motor door latch.

Categorisation

Props & Materials Required

  • •Laser-cut wooden safe locker box
  • •3x rotary encoder knobs (Hundreds, Tens, Ones)
  • •SG90 micro servo motor (door latch lock)
  • •16x2 I2C LCD screen display
  • •Arduino Nano / ESP32 controller board
  • •DFPlayer Mini MP3 module + 3W speaker

Step-by-Step Instructions

1

Draw a Secret 3-Digit Number

Pick a secret number card (e.g. 426). Expand it: 4 Hundreds (400) + 2 Tens (20) + 6 Ones (6).

2

Dial Hundreds, Tens & Ones

Turn Knob 1 to '4' (Hundreds), Knob 2 to '2' (Tens), Knob 3 to '6' (Ones). The LCD screen displays 'Code: 426'.

3

Unlock Servo Latch

Press the green 'Unlock' button. If place value dials match the secret code, the servo motor rotates 90° to unlatch the door! Speaker plays vault opening fanfare!

4

Place Value Breakdown Audio

Speaker narrates: 'Vault unlocked! Four hundred twenty-six is 4 Hundreds, 2 Tens, and 6 Ones!'

Why It Works & Notes

Understanding 3-digit numbers (Hundreds, Tens, Ones) up to 500 requires breaking numbers into place value components. A digital vault mechanism makes place value expansion an exciting puzzle: 'Set 3 Hundreds, 4 Tens, 8 Ones to open!'