This project is mainly about my new build process, which I used to create a single sided PCB for a rebuild of the Capslocker project from last year. Instead of using a laser printer to create an iron-on resist pattern, I'll cover a whole PCB in resist and then use a laser cutter to etch off the resist.
First, I created a new design in Eagle. I wanted this version of the Capslocker to be a little easier to program and adjust, so I added a potentiometer and a 6-pin AVR ISP header. It makes the device a bit bigger, but really makes it easy to modify the code.
Next, I lightly spray painted some single sided copper clad PCB material from Jameco. The best paint I've found is Rust-Oleum "Painter's Touch" flat black spray paint. It dries in about 20 minutes.
I set up the spray painted copper clad on the laser table and focused it as precisely as possible. A sharp beam is essential to getting a precision resist mask. Then I printed-to-file using a postscript driver, imported that file into Corel, converted to a 1200x1200 DPI bitmap, and inverted. I set the laser to 50% speed and 40% power, raster mode, bottom-up etching. It can be a good idea to print two copies since the second pass cleans up paint residue a lot, but it's not required.
Submitted by Garrett on Wed, 04/01/2009 - 23:47.
* Source code and Eagle PCB files: CapsLockerPCB&Code.zip *
Just in time for April Fool's Day! I built a device that has the potential to drive a computer user insane.
This device plugs into a USB port and implements a USB HID keyboard. Instead of doing anything useful, it waits between 30 seconds and 8 minutes and sends the scancode for the Caps Lock key. This will toggle the Caps Lock status on or off. Since the operating system controls the LED on the keyboard, the Caps Lock light also toggles. This makes it appear the user has accidentally pressed the Caps Lock key...until it happens 20 or 30 times and they get suspicious. Then they might see the Caps Lock light turn on by itself. Next is a sequence of reboots, bashing the keyboard on the desk, clicking through the Control Panel, possibly even replacing the keyboard. Unless they notice the tiny little device sitting in one of the USB ports on the back of their computer, nothing will help. Read more»
Submitted by Garrett on Thu, 04/03/2008 - 16:02.