Hi everyone! I'm currently working on redesigning Leah Buechley's Bike Light Jacket for a class I'm in.
I have found the components needed, including an Arduino FIO which has the exact same specs as the lilypad (it runs at 3.3V) . The only different in my set up is the board, the number of lights in the circuit and their voltage.
2 to 4 white LEDs: LED - Super Bright White (3.2-3.4V)
I've attached the Fritzing diagram. What do you think the best power supply for this set up would be? Should I go with a 9V Lithium or 3.7V Lithium? or am i just completely off the mark and should use a different power source?
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From what I can make out you have no resistors to limit the current to your LEDs - that's
necessary.
People normally use 3.7V batteries for this sort of thing, just enough to power blue
LEDs. Without the blue/white LEDs 3.2V would be enough, suggesting the safer
LiFePO4 batteries.
Hi guys thanks for the answer! i really appreciate it. I've uploaded a new Fritzing diagram with the other powers supply i was planning on using (this time linked to the power terminal). The two rows of 4 LEDs are going to be lit red and the two on the side are white.
Would this work? The setup im basing this off of does not use any resistors, should i be using them for the LEDs?
The first problem you now have is the current capacity of the IO pins. You will need a driver circuit to enable the LEDs to be driven from the IO pin.
If you use a transistor, you will have a voltage drop across it and will have to choose one capable of the current required.
You also have a lot of LEDs in parallel with no current limiting resistors. What tends to happen in this useage is that the slight difference in characteristics cause different amounts of current through each LED and hence different brightness. You will need to put one R in series with each LED, at 5v, 47 -100 ohm should do.
You also need R in series with LED near the switches. As it is coming directly from the IO pin and you need to limit the current to 10-20ma, you will need about 270 ohms.
You could use the higher voltage battery and put the LEDs in series, you would still need a similar R in series with the string.
The ws 2812 leds do not require current limiting resistors, in fact each one requires a connection directly to power and ground. They have data in and data out connections which allows you to daisy chain the leds' data line so only one uC I/o pin is needed to control hundreds of leds . check the datasheet. The white leds do require a current limiting resistor.
