Code and hardware for simulate a channel change in a old tube TV.

The Raspberry Pi change a random movie file in the folder 'movies' when the TV is showing a static noise. The static noise is provide by the TV circuit. A Arduino Mini Pro get the voltage on the tunning potentiometer and turn a relay on or off, selecting the TV composite video input or the noise from the TV circuit.

WARNING: Dangerous voltage inside TV set! Be Careful!

1. Demo Video

1. TV set:

The TV set is a 5 inch tube TV with AM/FM radio. The set is powered by a 12V DC external power supply and has composite video and audio input. This input is selected by a switch on the back of the TV set. The TV has a battery compartment in the bottom where I mounted the Raspberry Pi.

The tuning circuit use a potentiometer to variable the voltage to the TV tunner. The radio board use a variable capacitor. The variable capacitor and the potentiometer are mechanically connected to the tunning knob.

2. Hardware Schematics:

   • Relay Board:

   • Level Shifter:

   • Regulator module:

3. TV modification:

   • Remove the internal power supply transformer. The set will be powered by a 12V DC external power supply only.
   • Remove the battery contacts for more room for the hardware in the battery compartment.
   • Cut the tracks of the tuning potentiometer, isolated it and connect it to the Arduino board:
   • Isolate the video/TV switch and connect the wires to the relay board:
   • Get the 12V from the DC barrel connector.

All the wires are send to the battery compartment.

4. Software:
   • TVSim.ino = Scketch for Arduino Mini Pro.
   • TVSim.py = Script for Raspberry Pi.

For enable the Raspberry Pi composite video output use the command:

$ sudo raspi-config

Put the Python script in auto start for the Raspberry Pi boot.

5. Hardware inside the battery compartment:

6. Known problems and items for future improvements:

   • Sometimes the TV show the mouse cursor or the Linux terminal. (problem)
   • Movies always starts from the beginning. (improvement)
   • Different channels (scifi, horror, cartoons, etc...)(improvement)