| Borg Cube Panel Electronics |
aka Bob is assimilated by his Borg Cube... |
Touch Sensitive Controls
To implement the touch sensitive functions, I am using a Ramsey Electronics kit board. Each board provides 2 momentary contact switches, so I ordered 2 boards to implement power, reset, fan speed up, and fan speed down.
Ramsey Touch Switch Kit
These kits are very inexpensive, costing $6.95 each. My plan is to connect the switches to small copper plates cemented to the back of the transparency/acrylic. Gonna have to think about how to get that portion of the panel art to light up with copper blocking the illumination though! Probably take some experimentation.
Using these for power and reset is pretty straightforward. The switches do not provide perfect function, i.e. they are high resistance (but not infinite) when open, and low resistance (but not zero) when closed. Because of this, I may need to use them to control a relay if my mobo doesn't like being connected directly. No matter, it'll just take some experimentation to see what works.
Borg Digital Fanbus
The Fanbus will be interesting technology. As mentioned, I plan to use a digital potentiometer. This is a little IC chip (the one I'm using is made by Dallas/Maxim and costs about 6 bucks) that can take a couple pushbuttons as inputs and act like a potentiometer, changing resistance as the pushbuttons are clicked to increase of decrease. I'll interface it with one of the touch switch kits to provide button functionality, and with an Uller-style LM317 voltage controller and LED bargraph display to show the level. I haven't yet ordered these parts, but this path is pretty well trodden, at least the Uller stuff is. I have some application notes that tell me how to use the digital pot. I also have to decide whether to do the simple voltage regulator-type system or to attempt a PWM solution. The latter is more efficient and will generate less heat in the case, but it's harder to build.
I've also looked into the possibility of creating a PC board for the circuitry rather than just soldering up a rat's nest of wires. Here are some possible suppliers that will custom create a one-off PC board given a design:
http://www.expresspcb.com/:
These guys have their own layout SW too (it's free!) and were the most
highly recommended. Costs about $60 to have 3 identical boards made.
Not sure what I'd do with the other two, so I better think through carefully.
http://www.olimex.com/pcb/index.html:
Another possibility.
http://www.custompcb.com/:
One more possibility.
With the latter two, I'll have to scare up some PCB design software. Apparently it isn't too hard to come by. Many were recommending a package called Eagle.
Here's a potential circuit that turned up recently on Bit-Tech:
Resistor values rumored to be right for the digital pot, but this circuit is untested...
HD VU Meter
Here's a circuit I found from a Dutch guy who built one:
Ain't the Internet a beautiful thing?