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More Uzebox

Finally, I got the Uzebox to work! I’m not quite sure what made the difference, though.

First, I tore apart my earlier breadboard setup, and rebuilt the circuit from scratch, as neatly as I possibly could. Then I scrapped my grayscale DAC, and dropped the AD725 RGB to NTSC chip into the circuit (which had arrived in the mail since my previous attempts). Soldering the AD725 was my first experience at SMD soldering, and it was a little challenging, but not too bad. I managed to get 15 of the 16 pins soldered successfully on the first attempt, but the last pin just wouldn’t bond to the pad. I must have made 20 attempts to solder it, and was about to give up and solder a jumper wire to the pin, when I finally got it.

I connected the circuit to my finicky Dell monitor, turned it on, and voila! It worked!

The image quality is OK, but seems a bit blurry, and there’s noticeable color blooming. The interior of a red letter R is dark red instead of black, for instance. The photos here actually make it look cleaner than it really is. It’s certainly very playable, though, and maybe I’ve just forgotten what composite video quality looks like.

The rewired circuit on the breadboard:

Pac-Man title screen on the Dell monitor:

Pac-Man maze on the Dell monitor:

Read 4 comments and join the conversation 

4 Comments so far

  1. Dana - June 1st, 2009 10:21 am

    Ok I would like to try my hand at making that! i want to do it from scratch vs, a fuzebox/uzebox kit.

    My question is, were did you buy your Mega644, and AD725. And is the SMD a real b*tch to mount or is the a standard chip version. I have never tried a smd, but i am rusty at my soldering skills..

  2. Steve - June 1st, 2009 7:29 pm

    I bought all the parts from Digikey, except for the AD725, which I received as a free sample from Analog Devices. It was the first SMD device I’d ever soldered, and it was a little difficult, but not too bad. If you screw up, you can always just get the solder wick out and undo.

  3. AL - January 9th, 2012 8:20 pm


    Do you mind sending me a picture of the closeup DAC, the resistor array? I am having a hard time wiring this up correctly on the breadboard.

    my email address: unbonnevie AT yahoo DOT com

    Please replace “AT” with @ AND “DOT” with a dot, respectively


  4. Steve Chamberlin - January 9th, 2012 8:51 pm

    You mean the grayscale DAC? You can view a schematic at

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