Various ramblings – Electronics, radio, old computers, cars & other junk…

Category Archives: Computers

First milled PCB

After much tweaking, fiddling and procrastinating I have finally been able to successfully mill a PCB!

The only minor issue I had was with the drill file created by the PCB-GCode script which would not load correctly into LinuxCNC. Luckily this is a step that I can complete manually using my PCB drill.

The results are excellent, the finish is amazing and I am so very happy I won’t have to mess with PCB etchants and toner transfer ever again!

Mistakes on the mill…

While waiting patiently for the mill to finish running a PCB isolation route job I stepped away for a few seconds to skip a song on my music playlist. As I was fiddling with the music I heard the spindle motor starting to bog down and turned around to see that the cutting tool had started cutting deeper and deeper into the PCB material, the MDF board it was resting on and the PVC mill table…

I quickly hit the emergency stop button, killed power to the spindle motor and raised the Z-axis. At first I thought that the program had decided to plunge into the table but it quickly became apparent that was not the case. The heat of the spindle motor had made it slip down in the motor mount, the Z axis stepper had stayed perfectly still the whole time. I tightened the screws that clamp down on the motor and all seems fine now.

No real damage done to the mill, it’s just a little bit annoying… Ahh well!!

Etching boards – Round 1

My first attempts at etching these boards didn’t go so well. Using the toner transfer method has worked very well for me in the past, but it looks like my current printer doesn’t work as well as the one I used previously.

Below are a few pictures of the backplane boards I tried etching, the first photo based off a slightly older design with narrower traces. While the traces were etched fairly accurately, the surface of the traces has some fairly deep pitting where the toner coverage wasn’t thick enough. The worst of the pitting has eaten through to the fiberglass.

In some places the toner didn’t stick down very well, possibly because the board wasn’t clean enough or the toner hadn’t set properly. Ahh well, looks like more testing is needed.

While it is annoying to have wasted two boards worth of PCB material it is good to iron out these problems now. I have gone through all of the boards and increased trace width and also modified some packages to increase the size of pads and decrease drill size which should help with etching. Now I just need to improve the transfer process!

6502 computer project

While I was reading the Steve Jobs biography I was given for Christmas in 2011 I was feeling strangely nostalgic about the good ol’ days. This was strange mainly due to the fact I wasn’t yet born when the Steve’s (Wozniak and Jobs) were designing and building the Apple I & II…

Some time after that I read on Hack-a-Day about a 6502 based computer that Quinn Dunki was working on named Veronica, and instantly knew that I’d love to make something similar.

While not an exact copy of Quinn’s work, the design I have cobbled together does resemble hers quite a bit. My design is primarily based off of Grant Searle’s microUK101 design which itself is based off the UK101, a fairly early kit based machine. Both of those pages have huge amounts of information and are very well worth a read. I certainly read over them a fair few times to get my head around it all!

Just a few quick things, basically a warning to anybody reading this… I’m a “computer guy”, I earn a living working as a computer technician/network engineer. I have no formal training in the field of electronics (as I am very sure many of you will notice), most of this stuff is self taught. Accordingly, things on this page may be horribly wrong. If you do spot anything that is wrong, please let me know!

Building this computer is a way for me to learn more about electronics, mess with some hardware this is older than me for a laugh and have a bit of fun while doing it. If I stuff things up on the way to completion, hopefully I will have learnt something from those mistakes.

The 6502 computer project begins!

After reading over Quinn’s Veronica pages several times I started looking around for more information about various old CPU’s and systems I could base my own off. Very early on I decided on the 6502 as there were so many stable designs using it, and I figured this gave me the best chance of putting together a working computer.

After a fair bit of reading I decided on building Grant’s microUK101 design on a passive backplane borrowed from Quinn’s Veronica design.

After further research and many hours sitting in front of Eagle, the following PCB’s were created. Using the free version of Eagle was a bit of a challenge, the backplane just fits within the board size limitations.

Hammerhead 586 slate PC

Ruggedised slate PC – AMD “586” @ 133MHz, 32MB RAM, 1GB CF boot drive

I picked this computer up off eBay for $26. This beast is machined from a single block of aluminium (years before Apple!!). It is a bit of a slug, especially running Windows 98, but it’s more than capable of running solitaire which is great with the touch screen. Because it uses a magnetic touch screen it only works with the stylus, I’ve been spoilt by capacitive touch screens and I still get caught out trying to use it with fingers…

Not long after I got it up and running the hard drive died. This was a big deal as I hadn’t yet copied the contents of the drive, and after trawling the web couldn’t find a great deal of information about it nor any drivers. Luckily I managed to revive the drive for long enough to copy the contents using the freezer trick. I replaced the drive with a 1GB compact flash card, as a bonus it runs a little faster and the battery lasts a bit longer.