My 16x2 LCD serial backpack (a great project - thanks microcarl!) is becoming just too small for debugging with, so I've made myself a serial->TV display device. It produces a Black and White PAL composite video signal. It works nicely, but not very brightly.
I used a project at serasidis as the foundation of the circuit. Two output pins ; one sync, one pixel data. The problem is that the 'white' is very 'grey':
I now believe that this circuit shouldn't have the 75ohm resistor in it. The 75ohms is implied at the other end of the cable (inside the TV):
Am I right? Is the second circuit "correct"? In a fit of recklessness, I removed the 75ohm resistor from my circuit and tried it. It produces a much whiter output and the TV hasn't blown up so far. Am I safe, or do I need to check the batteries in my fire alarm?
Are there any simple improvements to the above circuit? It meets my target of 'simplicity', but should I be 'balancing' the signal or anything like that? Do I need a 75ohm resistor in series with the output?