I think i have worked out controlling the columns on the cubes, but I need some help with controlling the planes. One cube sinks(Shift register/resistor cube) the planes, the other cube sources(constant current cube).
It looks like the mosfets that I purchased are totally not appropriate for what theses, which kinda sucks, but moving on, I need to figure out a good way to sink, and source 5v upto 1 amp.
Based on what i've read, it seems like there are basically 2 viable options, Darlington arrays and Mosfets. It sounds like mosfets are a better option, because they waste less electricity.
So, it seems I should get an N channel mosfet or maybe I could use a couple ULN2803 chips for sinking the planes on the shift register cube.
How about sourcing 5v?, should I use a P channel mosfet? What are other options?
I understand that I want a fet with low RDS, typically measured in millionths of an ohm, What are all the factors I need to consider when shopping for mosfets?
Crossroads posted a way to sort through the mind boggling inventory at digikey, That is a good start. I tried to apply the concept at mouser, but that didnt work out well. Ebay, Thaishine, and Tayda all seem too difficult to figure out what part I want.
Newmark has a good looking search interface, but Im unsure exactly what things to select. I was able to knock the list down to 100 parts for both n and p channel at 1amp.
I think i also need the parts to be logic-level, that is to say, they can be switched with 5v.
Jameco has lots of parts, but the search interface is kinda difficult.
If I knew exactly what i was looking for, and exactly what specs I should be looking for would make it easier,
I am also uncertain about packages. for 1amp at 5v, I dont think i need any heatsinks, but I would rather buy a part that wont need one, if that is an option. Smaller (as in takes up less space), is better than bigger. SOT23 isnt too hard to solder, so even that isnt too small.
I've modified one of my charliecubes to use 100 ohm resistors, and it is noticably dimmer, Im going to try to measure some LEDs with a few different resistors sizes and calc the current use, and try to get them closer to 20ma. Nearest I can tell, I will have to settle for less current on the blue/green, If I drop to 50 ohm, that should put the blue/green at about 20ma, but the red should be over 20ma. Because of the layout, you can only use one size resistor and keeping red within spec means putting blue and green considerably lower current than red.
If you are considering trying music wire, I have found that for this size cube, 015 is too delicate (you can do it, but its very difficult), and 025 is more than sturdy enough, so Im going to try 020, I think it could be the ideal size for this size cube.