DIY Stupidly Bright LED Panel

[samwisekoi]

I have a new bike to commute on.  And when the days get shorter, I want marker light visible enough to ensure drivers see me.  So I designed the "Stupidly Bright LED Panel".


Stupidly Bright LED Panel by samwisekoi

This little 1" by 3" panel holds either 30 2v (white) or 25 3v (red) LEDs.  In three square inches.  It takes 12v.  It is designed to be easily daisy-chained.

Cree makes a 5mm white LED with 40,000 mcd, so one board will have 1,200,000 mcd.  Red or amber LEDs would be less bright, but fully populated you shouldn't be able to look straight at one.  Just what I want to ensure the cages see me.

The circuit on the board is designed so you can populate it one way and have a 3x10 matrix, and use alternate holes to have a 5x5 matrix.  This allows you to use 2v or 3v LEDs in the same circuit.

I'm going to get some of the boards made and volume determines price.  LEDs cost a quarter each at Mouser, and the PCB in qty=10 costs $15.  In qty-=100 it costs $2.

Oh, I need to say this:

I make no claims about how well these will work for YOU in YOUR situation, especially on a bike at night. 

These are not lensed, nor are they designed as headlights or to enable YOU to see.  They are designed to be seen by others, but YMMV.  Caveat Emptor.

Anyone else want some?

 - Ron | samwisekoi

[samwisekoi]

Mine.

[mkawa]

you need an optic

[samwisekoi]

you need an optic

I need to see some PCBs from pad2pad before I send GH75 there.  Also, hobby.

What is an optic?

 - Ron I samwisekoi

[mkawa]

a lens

the problem with SMT LEDs is that they're almost like lasers. they have very narrow lenses on them, practically collimators. in order to get usable light out of them, you have to put a an optical lens and assembly on them that will disperse the rays. it's easiest to do with a small number of LEDs, because these are typically molded..

BUT MAKERBOT!

muahahahaha

also if you just need something quickly (which you do), check out the niterider newts and the cygolites. in particular, this one: http://www.amazon.com/Cygolite-Trion-1200-Rechargeable-Headlight/dp/B0090QAUTQ/ref=sr_1_1?ie=UTF8&qid=1371051697&sr=8-1&keywords=cygolite+1200 (notice that the entire housing is a giant heatsink)

edit: MUAHAHAHAHA

also those smt LEDs, they get HOT AS ****

and they eat up a ****load of current. you need a HUGE CCS to drive that many

[samwisekoi]

Ah.  Not SMT.  5mm through-hole LEDs.  Mouser Part #:  941-C503DWANCCBEB151


Cree 40000mcd cool-white 5mm LED

15-degree spread (nominal) and I could add some wider-spread LEDs at the edges.  The array draws current of 200 mA from the source, total power dissipated by the array is 2400 mW. 

LED series/parallel array wizard

Nevertheless, I might drop a Fresnel on top for taillight use.  Otherwise, 30 laser beams is the goal, not an unwanted side-effect!

 - Ron | samwisekoi

[mkawa]

i see, so this is a purely "to be seen" light then.

[samwisekoi]

i see, so this is a purely "to be seen" light then.

Like bright colors on a hornet, yes.

[i3oilermaker]

Are you selling this as a kit or just a PCB?

If it is a kit can post the final price?  (with current interest)

[samwisekoi]

Are you selling this as a kit or just a PCB?

If it is a kit can post the final price?  (with current interest)

Well, it would be the PCB plus two items from Mouser.

$15.00 PCB $15 (or less)
$7.20   qty=30 LEDs     941-C503DWANCCBEB151 (40000 mcd Cool White)
$2.90   qty=10 resistors     71-RL07S-G-82 (82 Ohm 1/4w wire-wound)

$30 with shipping?  Slightly less for red.  I could make a kit, but wouldn't people want to choose their own LEDs?  For example, it would be easy to mix red and blue LEDs for the Blue Dot look.  Or trim the outside edges with amber.  (Technically, there are five circuits per PCB, so you could make it a rainbow if you wanted.)

Also, it occurred to me that at 12v, this could be used on cars, motorcycles, and for the insane, inside PCs where it would fit nicely behind an 80mm fan and blind people who looked too closely.

I'm going to breadboard a couple first, I think.

Anyhow, $30 or less.  Quite a lot less in volume, especially if you don't use the highest-power LEDs available.

 - Ron | samwisekoi



UPDATE:

Cree makes a 12000mcd red LED at 2.1v, so I can fit 30 super-bright reds on the board.  Also, I had choosen resistors poorly above, and instead found ones for .06 each.  Total Mouser order for 60 LEDs and 20 resistors was $14 plus shipping.

[OldDataHands]

Add provisions for a 555 astable multivibrator toggle for a blink function?
The blinky ones get my attention more than the steady ones...

[samwisekoi]

Add provisions for a 555 astable multivibrator toggle for a blink function?
The blinky ones get my attention more than the steady ones...

Like this?
https://www.circuitlab.com/circuit/e38756/555-timer-as-astable-multivibrator-oscillator/

 - Ron | samwisekoi

[OldDataHands]

Yep. You should be able to prototye easily,
and pick values that achieve a blink rate/duration that you like.

[damorgue]

Wimpy Wimpy Wimpy


Hefty Hefty Hefty

[samwisekoi]

Wimpy Wimpy Wimpy

Hefty Hefty Hefty

Streetlight on a stick!

I think if I made marker lamps like that, the cars would drive INTO me, not away.

I'm sticking with 10 to the square inch.  Feel free to daisy-chain 25 of mine together to get the same effect!  (I calculate ~50w or 5A at 12v.)

How long will those batteries last?

 - Ron | samwisekoi

[OldDataHands]

This 555 can directly source 225mA:
http://www.digikey.com/product-detail/en/NA555DR/296-21752-1-ND/1629153

If you need to provide more than that, you might need a capable FET. Maybe like this:
http://www.digikey.com/product-detail/en/SI2312CDS-T1-GE3/SI2312CDS-T1-GE3CT-ND/2441897

Maybe if you switch to SMD resistors there'd be room on the bottom for these SMD parts
without changing your form-factor?

[samwisekoi]

Alrighty then.

Now the PCB supports 7.4v systems (modern LED bike headlamps).  Still 30 LEDs, but now the resistor count is up to 15 (2:1 ratio with LEDs) to support the lower voltage.  Still stupidly bright, still provides daisy-chaining.

Also added was one dollar worth of a 555-based flasher circuit.  Add a slide switch for another couple of bucks and you can have each assembly be selectable for ON-OFF-FLASHING. 

I have not incorporated the circuitry to enable a pair of these to alternate while flashing.  Because if you connected a couple of these with a six cent resistor, and built one with red LEDs and another with blue LEDs, you would have a very bright flashing RED-BLUE-RED-BLUE light.  And that would probably be illegal to use to frighten drivers who just cut you off.

So to be clear, I do not support connecting a RED unit to a BLUE unit via pins 3 and 4 as shown on this diagram here.  And if you did such a thing, you should definitely not connect it to a remote momentary contact switch on your handlebars.  And especially don't add a pair of off-tone piezo speakers, or you would get a WOO-woo-WOO-woo sound along with your RED-BLUE-RED-BLUE very, very bright flashing lights.

That would confuse car drivers to the point where they might pull over to the side of the road.

But I digress.  Here is the revised, flashing, 30-LED Stupidly Bright LED Panel, now 3.5" by 1.125" in size.


30-LED Stupidly Bright LED Panel by samwisekoi

Ten bucks each for the prototype PCBs.

 - Ron | samwisekoi

[i3oilermaker]

If you source the parts for this as a kit you can count me in for one set.

[OldDataHands]

I'm totally in. (whether or not you feel like making a kit out of it) 
Should be entertaining!

[samwisekoi]

Update.

I added a transistor circuit just in case somebody finds even more powerful LEDs that take more mA than the 555 can handle.

Oh, and it is also possible that there are now COMPLETELY UNSUPPORTED AND UNWIRED power and ground holes for an 80 dbA piezo buzzer like this one ($2.05 at Mouser) 810-SD1614TT-B1.



So you could swap out four of the LEDs for a buzzer.  And probably find room for the rest of the buzzer circuit defined in the data sheet.  They come in 2048 and 4096 Hz with the same footprint in case you wanted two with different pitches for some reason.

Also, I added a sort of AUX IN input, in case you wanted multiple units to share a single timer circuit.  (In sync or alternating.)  And I added a cut line in case you don't want ANY of the extra electronics, and just want the dang LEDs.  Oh, and some M3/4-40 mounting holes.


Stupidly Bright LED Panel - Now with Smarts!

 - Ron | samwisekoi

[The_Ed]

I have a bag of those buzzers that I desoldered from NIB Cherry POS boards... I've used a few of them in test circuits, they like to scream at me... (Yes, I sometimes miss a 0 so there's 10x as much power as there's supposed to be... What's that smell? OH ****! TURN IT OFF!...) I would recommend people to have a few of them for test circuit purposes, but I would never purposefully subject myself to their screaming...

[samwisekoi]

I have a bag of those buzzers that I desoldered from NIB Cherry POS boards... I've used a few of them in test circuits, they like to scream at me... (Yes, I sometimes miss a 0 so there's 10x as much power as there's supposed to be... What's that smell? OH ****! TURN IT OFF!...) I would recommend people to have a few of them for test circuit purposes, but I would never purposefully subject myself to their screaming...

The_Ed-san,

The data sheet (translated from Japanese, I think) shows square wave input.  In your experience, do these work when straight DC voltage is applied?

Thanks!

 - Ron | samwisekoi

[The_Ed]

The ones I have from the POS boards scream whenever enough voltage and amperage is applied. You do not need to pulse the power, they already have their frequency built in. How loud they scream at that frequency is determined by how much power you give them (I usually give them 5 volts). But remember that just because mine work off of straight DC doesn't mean they all do.