Interactive digital frame
How it works? I put ten photos in the usb stick, every picture tells (oddly) a number, each photo is a level. To reach the next level I need to enter a key sequence, the sequence is the number. I used a tv remote control to enter numbers, each key has been decoded before. I used an IR receiver pcb taken from an old DVD player, an IR led transmitter taken from an old remote control, three red leds that represent the state of the input sequence and a buzzer to sound effects. If I enter the wrong sequence I can't access to the next level.