So remember that Shuttle computer we got a few weeks ago? Finally had time to install it as our backup shipping station and we couldn’t get the scale to work (its a serial port device). Turns out the motherboard “COM port dongles” were wired for a different kind of motherboard! So if you ever decide to do this yourself, note that the dongles come with ‘alternating’ pins when they really should not be. Check your motherboard documentation to verify which you need, and then a quick soldering fix!

PCBs are custom, expensive and non-returnable. That means you have to get it as close to perfect the first time or risk losing $!

One thing some people may not realize is that the EAGLECad DRC (Design Rule Check) will make sure your pads arent touching, traces aren’t crossing, drills are large enough, etc. but DRC doesn’t check for airwires!

For example, in this PCB layout, we have a DRC with no errors

But if you check the number of remaining airwires (click on the airwire tool and look at the bottom of the window) you’ll see that there are 2 of them.

When you’re done it will say “Nothing to do!” (which is a great feeling)

Remember: moving parts, changing the DRC, etc. can create little airwires. Be especially aware of shifting ground planes (which can be done by editing the DRC) that can create hairline airwires!

For my work, hobby and business, I need COMPUTING POWER! However, my needs are kinda picky and it took me many days to narrow down the ‘ideal’ hacking computer. This computer is for electronics hacking, and its also for business. Yeek! We got two of these, one as a personal workstation for all the web, graphics, programming, etc. And another one as the ‘business’ machine – for shipping, programming chips, etc.

It took a while to chase down all the parts for my perfect pair of computers, so we wrote it all down in case it would be handy for others

Here is what my specifications were:

1. Must have hardware/motherboard parallel port (printer port). Parallel ports are the pinkie toe of electronics hacking. Youd think they’d be gone by now but nooo, they’re still there, hanging around and often necessary for using older software/hardware/schems. I use them a lot for talking to laser and label printers, CPLD/FPGA programmers, bitbanging all sorts of stuff, programming chips via PonyProg, etc.. USB-parallel converters aren’t good enough due to the slowness from the USB layer. Hardware parallel ports are just damn handy!
2. Must have hardware/motherboard serial port (COM/Modem port). Two if you can. These are more common than parallel ports. You can use USB-serial ports for most things but sometimes you need the hardware speed of an onboard serial port especially if you’re doing some funky bitbanging.
3. Should be small, we dont got a lot of room here at adafruit.
4. Doesnt need hardcore video Not a lot of game playing around here, mostly working!
5. Processor type Can be Intel or AMD. Both are fine by us. Lately we’ve liked AMD a lot.
6. Lots of USB ports. Both on the outside and on the motherboard. Especially for the shipping computer theres just tons of stuff that needs to plug in – programmers, barcode scanners, scales, backup usb keys, Arduinos. You can also use hubs.
7. Whole machine for $500 Not including monitor, key/mouse, etc. We wanted it lean and clean. Of course, you can do better if you’ve got CDROM drives, hard drives, etc to recycle. Unfortunately we had recycled everything into other machines already!

Want something like this? Check out what we went with, we’re quite happy with the two machines!

Here’s another edge-lit acrylic / laser project! yergacheffe writes -

The idea is to illuminate a piece of clear acrylic from the edge and etch the acrylic so that the light reflects forward showing the image. I planned to use the Epilog Laser Cutter at Techshop to etch the image into the acrylic. Since the light entering from the LEDs is the same intensity for all areas of the image, we need some means of getting multiple gradations of brightness. I’ve previously described methods for turning photos into half-tone images and that’s what I did here as well. I took a photo and turned it into a monochrome bitmap using a 45-degree linear halftone.

One important difference in this case is that we want to etch the acrylic where we want light to shine. The laser cutter acts like a printer, and etches wherever there are dark pixels in the halftone image. So dark pixels in the image equates to light shining in the final product, which means I needed to invert the colors in the halftone which is why the picture looks spooky.

Doing anything with the laser cutter starts with finding the magic combination of speed, power and resolution that will give the best results with the material you’re etching. After a few test runs I found settings that gave me reasonable results.

If you’ve been using Mouser to buy parts lately, you may have noticed that with their recent site re-design they also added price sorting which is just fantastic. Unfortunatly, DigiKey hasn’t caught up but friendly poster morganl brought my attention to a GreaseMonkey script written by Sajid Sadi that adds a sorting ability while browsing. I tried it out and it works great!