I’ve used UV LED’s to build a PCB exposure unit, and that was very successful, so I thought I would see if a UV LED could be used to erase an EPROM.

As experiments go, it was rather a long shot. The UV LEDs I’ve got emit UV light at a wavelength of around 400nm, and EPROMs need to be exposed to UV light at around 250nm. However UV is UV so it was worth a try.

It didn’t work :(

In the end, it had around five hours of exposure and after reading back the EPROM contents, not even one bit had changed state. Still, I suppose it’s nice to know.

I’ve been working on some switch boxes for work over the last couple of days. I’ve got to build six of them and whilst they look complicated, they are really quite simple as there are no real electronics inside; just a lot of switches, LEDs, current limiting resistors and a couple of power diodes. However, some of the wiring needed to be capable of comfortably handling around 8 to 10 amps, so I had to go routing in the back of my cable cupboard to see what I had. I’ve acquired a lot of reels of cable over the years for various projects, and some of the reels weren’t labelled with their specifications other than just the cable size.

I found some information on the web that gives a rule of thumb for converting cable sizes to amp carrying capacity, and I’ve placed it in my technical documents section for those that may find it useful.

I’ve created a new tech tip article on the method I use for creating double-sided PCB’s for those that are interested. It’s really not that difficult and doesn’t require any special hardware, just a little bit of patience and care. Enjoy.

Well, I'm making progress on my PIC programmer. This has been one of those projects that has been overly difficult and problematic for no apparent reasons. I had problems with some of the switches with built-in LED’s I’ve been using; a couple of them were faulty and that caused me some head scratching for a while. Then my current PIC programmer would work with my PC at all; for some reason the USB card in the PC had come lose but again, I spent a fair amount of time re-booting the PC and messing around. Needless to say all the other USB devices that are plugged into the other USB ports were working fine. I then had problems getting the PIC (there’s a PIC at the core of my new programmer) to work correctly. For some reason the results were very intermittent and I was getting worried that the design was fundamentally flawed, but it turned out that there’s an “issue” with the AMICUS compiler which I need to report to the manufacturer. This really should have been a weekend type project instead it’s been dragging on for several weeks. However, I managed to get one of it’s channels up and working yesterday and it worked perfectly, so now I just need to etch a couple of additional boards for the  remaining programming channels, and then create some interconnect cables and it’s done.