Saturday, May 26, 2012

Remote power button

Visual layout

I recently set up my projector to enjoy movies more comfortably from my couch. To do this I decided it would be awesome to "hide" my projector inside of the closet that comprises almost an entire side of my apartment. I wanted the video quality from my computer to be halfway decent on the projector, so I decided to move the computer into the closet as well so it could sit next to the projector, and maintain a short run of cable. At the same time, I still wanted to be able to sit at my desk and use my keyboard and monitor like a normal computer.

Room Layout
This was accomplished by getting some cables from But I still had the nagging problem of always walking into my closet, and reaching to the shelf my PC is on, to turn on the computer. So I decided to install a remote power button into my desk, using a button I had bought for this exact purpose a couple of years ago. It is a particularly awesome button.

I spend some time this past week drilling a hole into my desk (which is basically extruded steel), into which I could mount the button. My first attempts consisted of using regular drill bits followed by a Dremmel to widen the hole (to .75 in). It only took me about 10 minutes of grinding away at the desk to realize I was using the wrong tool. So I went online and ordered a set of step drill bits. They arrived last night.

I managed to finish the job in another ten minutes. Nothing feels quite like using the right tool for the job. I mounted the button and proceeded to wire it up. Crossing my fingers and praying that the computer circuit just needed a normally open dry contact, I attached the button (I had left my multimeter at work), in parallel with the PC button pins. It worked!

Another lesson learned long ago, is conscientious wiring. I used a screw terminal on the outside of the PC case, followed by jumpers inside. So if I ever need to open my case later, I can just disconnect the wires inside to not be bothered.

I finished the wiring job and cleaned off my desk (killing two birds with one stone), to take some pictures. I really like how clean my setup is now (in both senses).

Friday, May 4, 2012

Light-It-Up Component Organizer

I got the idea for doing this from this guy: . After seeing that video and learning about the TLC5940NT (a 16 bit PWM driver which can be daisychained to even greater orders), I felt inspired to finally clean up my lab supplies. I have too often felt disrupted by not having parts when I thought I did, and not knowing where those parts were when I needed them. With this system I will hopefully solve both problems, as my entire inventory will need to be recorded, and organized.

Designing the PCB's for the control circuit was simple enough. I just followed these diagrams: The main challenge so far in the project is keeping costs down while retaining a higher level of quality than I have adhered to in my projects so far. I have a bit more money to invest in this project, so I intend to make it as clean as possible.

Here's a picture of my proof-of-concept. The trouble with clear drawers is the light cross-talk between drawers when they are lit from the rear. To solve this issue I taped some aluminum foil around the drawer like a hotdog bun.  This solves the issue in the left, right and down directions, but all the drawers above it are still lit. So by adding a second hotdog bun to the drawer above, the original drawer becomes a light-pipe of sorts. I really like how the drawer is fully lit, with the light completely diffused. Of course when the idea is actually implemented I will be using a silver paint and not foil...

I also tested how the concept worked when actually filled with items and I am pleased to say that it works quite well. More on that later.

I started working on the LED backplane last night. I had designed a PCB to accomplish the task, but actually having the PCB made was going to be far too expensive. So I went ahead and tried to etch my own board. The size of the design proved to be too much for the process. I could not get the resist layer to adhere very well to the clad. So I have started making the PCB manually from proto board. It is about as much fun as counting grains of sand. To ease (or add to?) the tedium I bought "Atlas Shrugged" on audiobook. So far, 8 LED's (out of 64) are connected... this project will take some time...