Secret Code Box Add-on Kit with 4x4 Keypad & SG90 (No Board)
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Prices updated: 13 Oct 2026
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About this product
Add-on kit for a secret code box. A 4x4 matrix keypad receives the code, and the Arduino compares it with the stored password. If it matches, a servo unlocks the lock and a green LED lights up. If it does not, a buzzer sounds three times. The Arduino board is not included, and this is an educational box, not a real security lock.
Specifications
- Keypad
- 4×4 matrix (16 keys)
- Servo
- SG90 micro servo
- Breadboard
- 400 points
- Controller board
- Arduino Uno (not included)
- Recommended age
- 10–12 years
- Level
- Early intermediate
- Soldering
- No
- Estimated build time
- About 1.5 hours
Frequently asked questions
Does this add-on kit work on its own?
No. It needs an Arduino Uno or a compatible board, and a computer with the Arduino IDE to upload the code. The keypad reading in this project uses the Keypad library.
How is the 4x4 keypad wired?
A 4x4 matrix keypad has 8 pins: 4 rows and 4 columns. These connect to 8 digital pins on the Arduino, and the pin numbers must match the ones defined in the sketch.
