TV B Ours

Oct 30, 2009

First, there was TV B Gone, a brilliant little device that kills any old TV. And it was good. But what if you want to add something of your own? Throw your own little secret spice into the viewing experience?

Introducing TV B Ours

We had all sorts of plans to build this into a kit and distribute it, but so far that hasn't happened. So, in the mean time, here's all you need to build your own.

Parts

• 1 - ATtiny44 microcontroller
• 1 - 20MHz crystal/resonator
• 1 - 10K ohm resistor
• 1 - 1K ohm resistor
• 2 - 499 ohm resistor
• 1 - 5V regulator
• 1 - 3.3uF capacitor
• 1 - 4.7V Zener diode
• 2 - N-Mosfets
• 1 - male RCA connector
• 1 - female RCA connector
• 1 - 9-volt battery, or other batteries to make at least 6V

Circuit

All things considered, the circuit is fairly simple. The basic idea is the microcontroller outputs a single NTSC video frame in 2 colors, using a 2-pin DAC. It stops the incoming video by shutting it off with the MOSFETs, and then sends its own video.

• Eagle files: tvbours_eagle.tar.gz

Code

The code is written in assembler, in order to be as efficient as possible and leave maximum space for the video frame (we're really pushing the limits of the $2 microcontroller here). To make the process of creating images easier, there's also a python script which converts images into asm files which can be included before compilation.

• Microcode: tvbours_microcode.tar.gz
• Python script: img_to_db.py

GUI uploader

And to make things even easier, we wanted to provide a GUI uploader that could change the image loaded on the device without having to recompile. This requires the use of a serial connection with the device. ....