---
title: "Adventures in 2068 Video, Part II"
id: "24710"
type: "post"
slug: "adventures-in-2068-video-part-ii"
published_at: "2020-01-20T23:15:08+00:00"
modified_at: "2022-12-31T01:21:06+00:00"
url: "http://localhost/blog/adventures-in-2068-video-part-ii/"
markdown_url: "http://localhost/blog/adventures-in-2068-video-part-ii.md"
excerpt: "In my previous post, I had revised my converter to use the LM1881 dedicated sync separator. Results, unfortunately, were poor. So, I went back to the data sheets for the AD724 RGB to NTSC/PAL Encoder and the LM1881 Video Sync..."
taxonomy_category:
  - "Blog"
taxonomy_post_tag:
  - "TS 2068"
---

In my previous post, I had revised my converter to use the LM1881 dedicated sync separator. Results, unfortunately, were poor.

So, I went back to the data sheets for the [AD724 RGB to NTSC/PAL Encoder](https://www.analog.com/media/en/technical-documentation/data-sheets/AD724.pdf)
 and the [LM1881 Video Sync Separator](http://www.ti.com/lit/ds/symlink/lm1881.pdf)
.

Poring over them revealed I’d benefit from a few more capacitors. I also switched from a 3.58mhz color burst oscillator to an oscillator that runs at 14.318mhz, or four times as fast. The AD724 can take either signal, so I thought I’d go with the higher one. With the lower frequency oscillator, the AD724 uses an internal phase-locked loop to generate a 14.318mhz clock. If you use the 14.318mhz oscillator, that PLL is bypassed.

I also added some jumpers to the red, green and blue inputs from the computer, in case I wanted to adjust the input impedance. I did the same to the composite output.

Here are the resulting schematic and PCB.

My first attempt at building this didn’t go well: it didn’t work at all. I’m not entirely sure what wasn’t working, so I built a second and took a little more time to test along the way.

Note: there was an iteration before this that used a 78M05 connected to the computer’s +15v to generate on-board 5v. Turns out that wasn’t necessary.

And here are the before and after results. I think this is about as good as I can get it. The signal is a little hot and has some ghosting, so adjusting monitor brightness and contrast is required.

The crazy moire pattern is from the camera.

### Tags

[Blog](/category/blog/)
[TS 2068](/tag/ts2068/)

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### About The Author

[David Anderson](/author/david/)
I'm a big fan of the Timex/Sinclair computers: my first was the TS 1000. I love building things for my TS 2068 and sharing them with others on this site and andertone.com.