Hello all. 
I am collecting parts to build a simple supergun for a couple of jamma boards I have at the house. 
In all of my research on the topic I have found references to two specific video encoders, the jrok and the neobitz.  I can find neither available anywhere for purchase. 
What I can find, however, are cards that convert RGB to VGA. I have a couple of these cards available. Thinking of using one in the supergun. 
Anyone have a solution to convert that VGA signal to Composite?  Anyone making jrok type encoders currently?