I’ve got a few of these old portable CRT TVs laying around and I thought I might use one of them for a display for a homebrew computer I am working on. The computer outputs a composite video signal, but these TVs are RF only, so I figured I’d try to mod one to add composite in. The TV I went with is a Bentley 100C. Mainly because I like the way it looks.
I finally had a few days off over the holiday weekend and was able to follow along with Ben Eater’s 6502 computer series on youtube. The videos series is well done and the build was pretty straight forward. The schematic for the final computer is below. I didn’t take too many pictures of the build process. I did start out with a different breadboard layout, but it was getting a bit cramped, so I built out the address and data buses down one side of the breadboard which made things much easier.
I picked up this c64 a while back at an estate sale. It was stored down in a damp basement and was pretty well coated in dirt and grime. Unfortunately, I didn’t take a picture of the case before I cleaned it up, but trust me, it was gross. After testing it, it did work without issue. Well, the VIC is pretty bad. The video quality isn’t great, but it does work.
A few weeks back, my son was digging around my parent’s attic and found an old laptop that I picked up in high school. The laptop is a Chaplet Systems Halikan NBA486. I found it in one of the cabinets in my electronics class and it was already almost a decade old, so my teacher said I could keep it. It didn’t have a battery or a power adapter, so I was never able to do anything with it, but when my son brought it home, I told him we’d try to get it working.
A while back I found the RC2014 project which is a modular z80 computer. I’ve been wanting to play around with the z80 and this looked like a good place to start considering I already had most of the parts. The RC2014 is designed around modules that plug into a back plane. There are many modules available, most of which have published schematics, so it was fairly easy to get started.
Over the last few weeks, I’ve picked up several atari game consoles like the 2600, 2600 jr, and a 7800. I tried hooking them up via RF, but the quality is terrible on my TVs, so I went looking for composite mods. I started with the 2600 junior. I built a single transistor amplifier and wired it in, but I was getting some strange behavior with the video. I then tried a more elaborate multi-amplifier circuit, but saw the same issues.