Introduction: Arduino DTMF Code Locker. a Hidden Lock for Your Secret Spaces.

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Atmega328 device that listens for dial tones from mobile phone via a microphone.

So it can be placed behind the locked door without requiring extensive carpentry.

If code dialed matches the stored one lock will open for a few seconds.

Supplies

Any arduino with atmega328 MC (Mine is arduino extra mini).

Microphone and LM358 or MAX4466(better) mic amp.

RGB led with four pins, common "-".

Some transistor to control lock or motor or whatever.

Step 1:

Connect pins as:

R led - D5

G led - D6

B led - D7

Audio input - A0

Reset button - D12

Lock pin - D8

Step 2:

Compile with arduino sources or burn already compiled.


  1. Connect all together and poweron.
  2. Dial the new password twice while the red led is on. 5 digits (0-9, *, #, A, B, C, D)
  3. Both the lock and master codes will be set to this password!
  4. If everything is set correctly, the white light (R+G+B) will appear. Reset.
  5. Now, enter the master code to change the lock code.
  6. Write down the master code somewhere, it is used to change the lock code.
  7. Dial lock code to get access to whatever.

Step 3:

Any mobile phone can be used, turn loud dialing tones on.

Also free app ToneDef from F-Droid repository allows to use whole 16 tones including extended ABCD chars.

Step 4:

Read github for more details.

Youtube for some operation video.

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