Wiring an LED bar graph array?

[Matt Thorn]

Matt, the specs provided apply to each segment - each LED requires 2-2.5V @25mA. So if you run all the LEDs in the bargraph in parallel, that means the current requirements get added up - 250mA total. The voltage requirements stay the same.

What Xwing is refering to with the US, is the voltage is adjusted automatically, and feed what the LED requires - so you don't need to worry about that - just pay attention to the current requirements.

I've wired up accent LEDs with an ultrasound (just like he described), and you'll see that with that much required current, you won't need a resistor anyway.

So since the LED array hooked up in parallel would require 250mA, I wouldn't need a resistor at all? And hooking it up in parallel would basically mean connecting all the positive posts together, doing the same with the negative posts, then putting the array between the Luxeon III and the Ultrasound board...?

... and last thing, Matt - multi-quote & edit buttons are your friend

They will be from now on, yes.

[eastern57]

So since the LED array hooked up in parallel would require 250mA, I wouldn't need a resistor at all? And hooking it up in parallel would basically mean connecting all the positive posts together, doing the same with the negative posts, then putting the array between the Luxeon III and the Ultrasound board...?



They will be from now on, yes.

Parallel means both are running from the same sources (i.e. LED pads)... and strangely enough, yes, it will work - and not overload - without a resistor... I don't have an explanation for that yet.

[Matt Thorn]

Parallel means both are running from the same sources (i.e. LED pads)... and strangely enough, yes, it will work - and not everload - without a resistor... I don't have an explanation for that yet.

Thanks! I'll give it a try.

[Matt Thorn]

Reviving an old thread here. I finally got around to making this project a reality (?), and would be grateful if someone with more electronic expertise could check this wiring diagram for me. Apologies for scribbling rather than using Fireworks or Photoshop, like I usually do, but I was in a bit of a hurry, and I think (well, hope) the diagram is pretty easy to read. From what everyone told me, I gather I don't need any resistors, since the Lux III, accent LED, and LED bar gragh array are all powered by the MR board.

Yeah, I know it looks like a sketch of the internal organs of some rare deep-sea fish, but it's actually a light saber. And the position of things will be basically as I drew it. Here is the hilt it is going into.





Unlike the color-changing saber I just finished, in which I obsessed over the wiring, and the hilt was an afterthought, in this case I was stupid enough to build the hilt before giving serious thought to the wiring. In fact, I finished the hilt more than a month ago. And, of course, the idea for the hilt was based entirely around the idea of using an LED bar graph array that actually lights up. My original plan was to make a replica of a clan saber that uses the array, but I decided it would be too difficult, and besides, I liked my own design better.

Note that I haven't actually put a switch anywhere yet. (The "knobs" on the left-hand side are purely cosmetic thumbscrews.) I was hoping to make the array work as a switch, but decided that would be biting off more than I can chew, so I'm going to add a latching switch, probably on the underside, directly opposite and just above the array. (Oh, I'm using an MR Mace board now rather than an UltraSound; thus the latching switch.)

[Jay-gon Jinn]

Most of the diagram looks okay, but you have all of your led's wired in series not parrallel. For a parallel connection, you attach all of the negative together, and all of the positives together then attach to the board's respective outputs.

[Matt Thorn]

Most of the diagram looks okay, but you have all of your led's wired in series not parrallel. For a parallel connection, you attach all of the negative together, and all of the positives together then attach to the board's respective outputs.

Great. That's exactly the kind of feedback I was hoping for. Thanks!

[Sairon]

Thats a nice looking saber if I may add.

[Lord Dottore Matto]

Matt, I'll echo Jay-gon. Definitely run that in parallel not in series. The MR board will not light that array in series (at least not well).

BTW, I should mention that I am impressed with the way that you are a problem solver and always seem to be thinking. Kudos to you.

[Matt Thorn]

Matt, I'll echo Jay-gon. Definitely run that in parallel not in series. The MR board will not light that array in series (at least not well).

BTW, I should mention that I am impressed with the way that you are a problem solver and always seem to be thinking. Kudos to you.

Thanks, Sairon and LDM. I hope the final saber justifies the praise.

[FenderBender]

Impressed I am also with the progress you have made in the last couple of months! Great shroud work on that hilt man. Love the little band around the accent LED. *Fender' apologizes in advance for stealing that idea*