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Angus Hines
02-28-2009, 6:07 PM
Things to do with scrap piece's.

the clear is 1/2" and the black caps are 1/4" and overall it's 24" x 6" x 12"

I intentionally Crakled the edges by sanding real quick and then rubbing acetone all the way around. To give an ice looking effect asnd hide exactlay how the LEDS are in there.

The holes were drilled in the edge of the acrylic an then I hard wired 18 - T-10 LED bulbs then the whole cavity was potted using a good heat sink epoxy.

Steve Clarkson
02-28-2009, 6:52 PM
Angus.....that's AWESOME!!!

Can you do the tutorial on hardwiring LED?

Angus Hines
02-28-2009, 7:00 PM
Sure I'm wondering if I should just stick it here. Or do something seprate. It's really not that much to it.

Let me think and I'll get it up.:)

Steve Clarkson
02-28-2009, 7:15 PM
Not much to you maybe.....but to those of us electronically challenged.....it would mean alot!

Thanks!

Scott Shepherd
02-28-2009, 7:52 PM
Let me see if I understand this right Angus, you made a ShopBot sign on your laser? I hope your doors are locked, the BotHeads will be coming your way with tar and feathers shortly ;)

Angus Hines
02-28-2009, 8:33 PM
Naw, it's all about edge quality they'll understand...and it's actually in the Bot office's now.


Let me see if I understand this right Angus, you made a ShopBot sign on your laser? I hope your doors are locked, the BotHeads will be coming your way with tar and feathers shortly ;)

David Fairfield
02-28-2009, 10:36 PM
Bit smaller, same idea :) This one is for HO scale structure and powered by 1 LED

Bob Cole
02-28-2009, 10:47 PM
Wow. That is a really small sign. Both signs look great.

I haven't figure out how to make money on those types of signs but enjoy creating them.

Dee Gallo
02-28-2009, 10:56 PM
That is SO cute, Dave! You model people kill me... I love miniatures.

Bill Cunningham
02-28-2009, 11:26 PM
Not much to you maybe.....but to those of us electronically challenged.....it would mean alot!

Thanks!

here is something that was posted a while back Steve.. It will help you design a led array..
http://led.linear1.org/led.wiz

Steve Clarkson
03-01-2009, 8:25 AM
Thanks Bill......this looks like it will be very helpful......once I figure out the difference between diode forward voltage and diode forward current.......

Henry Ott
03-01-2009, 11:11 AM
Steve,

Most diodes will have a maximum of 30 milliamps Forward Current except the Blue diodes. Those it is safe to stay at 20ma.

The forward voltage will vary from 1.5 volts to 2.4 volts for the larger/brighter red diodes.

Looking at a diode from the top you will see one part has a flat edge this is the Cathode or negative terminal. It most always is the shorter of the two terminals this side you'll connect the resistor from the calculator to and the other side of the resistor goes to the (-) terminal on the battery. The (+) side of the battery goes directly to the Anode of the diode, this is the longest leg of the diode.

If you wanted to play around you could use a dual 'AA' battery keeper for 3 volts and a single 100 ohm resistor, or if you had handy a 9 Volt battery snap use a single 390 ohm resistor.

To do a string of LED's use the calculator assume all diodes to be 1.7 volts Forward Voltage and Forward Current to be 20ma and wire accordingly. This way you won't be Dark Emitting Diodes (DED's) in quick order.

This will give you a hint on how to play with the calculator Bill points too. Have Fun!


Do you think he got it, of course he got it, he's a laser guy! Okay we're going back to looking for Wenge and Cocobolo. It's times like these we really should have bought that pdf program.

Steve Clarkson
03-01-2009, 12:54 PM
Nope......didn't!

Guess I'll just have to stick to using LED Christmas lights.......

Angus Hines
03-01-2009, 2:00 PM
I told you it was simple Steve......LOL.

Basically, pick your wall wart voltage. Pick a resistor to match your input power source. (470 ohms for 12v) which is all I use well somtimes I'm forced by the nature of the job to use 24v -32v (but thats a whole nother solution).

Solider the resistors to the (-) pole(the shorter one) of the LED. I do this for each LED instead of doing array's (Resistors are cheap < .01 ea.).

Then wire the string together and hook up your power source.

If you need resources just PM me.......I agree with Keith's post in the Lumber Yard. And Im not giving anybody any free google hits.

AL Ursich
03-01-2009, 4:23 PM
Projects like this are in my future and I am a electronic WIZ having fixed Play Station units for Sony.... I am taking the easy way out with my LED's by using the Strip LED's on a reel.

All you need to do is cut them to length using the marked line EVERY 3 LED's. It has a copper pad marked + and -. All you need to do is solder a wire to each pad and use a Radio Shack 12 volt Wall Wort Transformer.

You can cut them any length as long as you cut them on the cut lines every 3 LED's.

I have White, Red, and Blue. Got them off of eBay for about $90.00 for 6 meters or about 19.6 feet. Really EASY to do....

Sure I could do the LED and resistor thing.....

Hey since we are talking LED's.... For a Outside LED Sign you could use the Solar LED's with the small charger and rechargeable batteries. I am still working on the V Carved Solar LED version.

My problem is the cold weather and short daylight of the winter does not let the small AA batteries take on enough charge. I did a mock up with D batteries for better life. Still in prototype with the chargers.

The Solar LED's also on eBay can fit in the base just like the Shop Bot sign.

Nice Job !!!

AL

http://www.sawmillcreek.org/showthread.php?t=103444 Post #3

Bill Cunningham
03-01-2009, 10:15 PM
Nope......didn't!

Guess I'll just have to stick to using LED Christmas lights.......

Just a simple application of Ohms law will give you everything you need..
The simplest way to remember it is using the old sayings
Women Are Virgins
Virgins Are Rare

the the formulas are
W
--------
A V
(watts divided by Amps = Volts, Watts divided by Volts = Amps, Amps x Volts = Watts)

and

V
_______
A R
(Amps x Resistance = Volts, volts divided by Amps = Resistance, Volts divided by Resistance = Amps)

So using Angus's example (470 ohms for 12v)
R = 470
V = 12

12/470=.0225 (22 ma)

Modern electronics now uses E for Volts(Electromotive force), P for watts(power), I for current (amps) and R for resistance in ohms

And, in keeping with the engraving theme, here is a complete Ohms Law Wheel you can engrave, or print out, and stick on the wall.. (I think it's in ver. 4)

Steve Clarkson
03-02-2009, 6:41 AM
Thanks Bill....I'm sure this will come in handy once I learn how to decifer it.

Dan Hintz
03-02-2009, 11:58 AM
Bill,

A good college try, but with your numbers Steve would be pulling a lot less than 22mA. You forgot to take the LED voltage drop into account.

Let's try another example:
Start with a 12V supply and attach 4 red LEDs in series (red LEDs typically have a forward voltage drop of around 1.7V at 20mA, give or take... read the datasheet or back of the box for specifics). Let's say we want to run 20mA through the string.

The voltage we care about is 12V minus the total LED votage drop of 6.8V (1.7V times 4), leaving us with 5.2V not dropped by the LEDs. The resistance needed is R = 5.2 / 0.020, or R=260 ohms.

The resistor will sink 0.104 Watts (P = 0.020A times 5.2V), which is easily taken care of by a 0.250W resistor found at Radio Shack.

Steve Clarkson
03-02-2009, 12:03 PM
Bill,

A good college try, but with your numbers Steve would be pulling a lot less than 22mA. You forgot to take the LED voltage drop into account.

Let's try another example:
Start with a 12V supply and attach 4 red LEDs in series (red LEDs typically have a forward voltage drop of around 1.7V at 20mA, give or take... read the datasheet or back of the box for specifics). Let's say we want to run 20mA through the string.

The voltage we care about is 12V minus the total LED votage drop of 6.8V (1.7V times 4), leaving us with 5.2V not dropped by the LEDs. The resistance needed is R = 5.2 / 0.020, or R=260 ohms.

The resistor will sink 0.104 Watts (P = 0.020A times 5.2V), which is easily taken care of by a 0.250W resistor found at Radio Shack.


And you wonder why I use LED Christmas lights...........