Hey everyone,
I'm building a 4x4x4 led cube with tlc5490. Should i use mosfets or transistors for multiplexing?
MOSFET for lowest losses. A bipolar transistor has a voltage loss of 0.7V - if you can live with that, it's probably fine, too.
Remember, MOSFET is acronym for "Metal Oxide Field Effect Transistor" - So it's a transistor, too.
I would recommend doing a 5x5x5 so you have a center column - makes the animations much more fluid when they can revolve around a center column.
// Per.
OK, I'll use mosfets then. 5x5x5 cube definately would look cooler. Unfortunately it's too late. Thx for reply.
"A bipolar transistor has a voltage loss of 0.7V..."
The "loss" here, supposing a common emitter circuit, is related to VCE and that is a function of collector current - little collector current, little "loss"; substantial collector current, more appreciable "loss".
"0.7V" would be the result on the output of a common collector circuit (vs. base voltage .)
For a 4 by 4 by 4 cube, you just use a single MAX7219. Works superbly and no need for transistors.
So i can use arduino pins instead to multiplex?
AwFro:
So i can use arduino pins instead to multiplex?
Yes, if you use transistors with any pins that would need to source or sink more than 40mA, for example the pins controlling the layers. You will also need more series resistors, one per column.
You would need 20 pins for a 4x4x4 cube. This means an Uno would not have enough pins because you can't use digital pins 0 or 1 because they are needed for sketch upload.
Also on Uno, there are only 6 pwm pins, so if you want brightness control over every led in the cube, you would need to do pwm in software.
Paul