Hey I want to create something like this (http://forums.pcapex.com/showthread....ht=buy+acrylic) however it will be a desk sign that says my name, or i might even change to become a door sign which in the end will light up my name that will be etched into the acrylic. I will be using a thin cellphone battery for power (1000mah, 3.7v Lithium Ion or another cell/Ngage/PDA battery with similar or better specs) So i have 2 questions:

1) I cant find my physics notebook from highschool which has all my electricity related equations in it, and i want to find out how long 2 LED's (30mah, 3v for argument sake) would last in terms of time with this kind of setup. So if someone knows the equation(s) to determine this it would be appreciated very much so.

2) I have never done such a thing before so im just wondering what thickness of acrylic i should use. LED's are 5mm, and should i just account for 2mm on each side, or do i need to go thicker. so am i looking at a 10mm thick sheet?


Edit: So thats what i mean by a desk sign, where the thin battery will be concealed in the black base, and it will probably have chromed strips on the top and side to hide the wires and give it more of a stealthy appeal to it, not to mention, chrome, glass, and black mix very well in a modern office enviroment.

The battery should last a loong time since your only consuming 30mA (which isnt alot).

Opps it should be 60mah since there are 2 LED's in a parallel setup, at 3v approx , but yea i think ur right, its still aconsiderable amount. Im gonna setup 2 blue LED's on the battery tonight once its charge and im gonna time how long it will last. Since talk time on my phone is approx 4 hours, with voice transfer and LCD screen, thats ALOT considering it will only be lighting up 2 LED's, so i hope to get quite the juice out of it. I personally would love to see atleast 8 hours worth (a full working day). but even 1 or 2 hours is all i practically need. I will share my findings when im done

The setup:

2 Blue LED's:

Parameter Min Typ Max Unit Luminous Intensity 4300 5100 5900 mcd Viewing Angle ~ 25 ~ Deg Peak Emission Wavelength ~ 470 ~ nm Forward Voltage 2.8 3.6 4.5 V Reverse Voltage ~ ~ 5 V Forward Current ~ 20 30 mA Reverse Current ~ ~ 10 uA Operating Temperature Range -40°C to +80°C Storage Temperature Range -40°C to +80°C Lead Soldering Temperature (4mm from body) 260°C for 5 seconds Color

The typical voltage is 3.6 and the battery is rated at 3.7 so i will run it at 3.7 and current at typical is approx 20mah each so i will rate it at 21mah each to account for the extra 0.1 volts. So for a parallel setup it will be 22mah at 3.7 volts a piece.

V=IR thus Resistance = 88 ohms

Check out this web-site....All things Light up
http://www.elwirecheap.com/inligupprod.html
and
http://www.thepcmodshop.com/products.htm#
LEDS
http://www.superbrightleds.com/leds.htm

thanks for the links thrash. I found http://www.elwirecheap.com/inligupprod.html useful because it ships to Canada so if i need cathodes or something in the future i willlook at them. But no LED's there unfortunetly . Other links were too expensive compared against similar offerings (lsdiodes.com) is still the cheapest for canadians to get LED's/Resistors to my knowledge. Hopefully they come out with an 8000mcd or higher Blue or light blue LED soon for this project

Ok, I have worked acrylics before, so I have some suggestions for this project...

Try smoke mirror backed acrylic in say 2mm thickness, (the color is called bronze).
one sheet of that in front, take stincels and use them backwards on the 'grey' side (when you see this you'll understand -0- the mirror side is gray the shiny side is a dark bronze color that reflects)..anyway use the stincels to write out what ever your sign is to say (remember do this backwards-) Take some acetone (nail polish remover) and carefully remove the mirror backing on the 'letters'...take your 3mm sheet of clear blue and do the cut outs for the lights at each side as your drawing had suggested...also cut out for the cell battery....take a 2mm black sheet and sandwich this all together - when on the blue will show thru the bronze where the letters where 'removed' from the mirror backing..oh, one other note there is a product called E6000 which is a glue for acrylic - be very light with it on the mirror backed front sheet because it can cause the mirror backing to distort.

Quote: Originally Posted by SiathLinux Ok, I have worked acrylics before, so I have some suggestions for this project... Try smoke mirror backed acrylic in say 2mm thickness, (the color is called bronze). one sheet of that in front, take stincels and use them backwards on the 'grey' side (when you see this you'll understand -0- the mirror side is gray the shiny side is a dark bronze color that reflects)..anyway use the stincels to write out what ever your sign is to say (remember do this backwards-) Take some acetone (nail polish remover) and carefully remove the mirror backing on the 'letters'...take your 3mm sheet of clear blue and do the cut outs for the lights at each side as your drawing had suggested...also cut out for the cell battery....take a 2mm black sheet and sandwich this all together - when on the blue will show thru the bronze where the letters where 'removed' from the mirror backing..oh, one other note there is a product called E6000 which is a glue for acrylic - be very light with it on the mirror backed front sheet because it can cause the mirror backing to distort.

I was going to take this approach at first until i saw the post (see my first post link) with the transparent etched acrylic effect and thats a look i prefer to go to because it looks more sleek and elegant, i dont know how to describe it. Just looks really neat.

In all honsety, I don't see why you're planning on using a battery pack. I'd buy one of those inexpensive multi volt adapters from Radio Shack, wire up an adapter harness so you can unplug the adaptor . . . add a power switch . . . Unless it's a matter of not wanting any visible wires coming outta the sign, in which case, just disregard this.

Quote: Originally Posted by drougnor In all honsety, I don't see why you're planning on using a battery pack. I'd buy one of those inexpensive multi volt adapters from Radio Shack, wire up an adapter harness so you can unplug the adaptor . . . add a power switch . . . Unless it's a matter of not wanting any visible wires coming outta the sign, in which case, just disregard this.

Yes i dont want any wires sticking out as it must look as nice and slick as possible ,as well as im making 2, one for my desk at my business, and one for my locker at school. For the one in my locker it will have a slightly different design giving me more space so i can fit an unused regular sized Audiovox CDM8900 cellphone battery (1000mah, 3.6v, so far it has been running on my test setup for 4 days non stop and still has 4/4 battery bars). For my business desk, i wil be using a Motorola V551 Slim battery pack (800mah, 3.6v) that i got off ebay for 8 bucks which wont last as long but it fits into a tinier package. The reason i am using cellphone batteries is because the Charger cable is much smaller then a regular adapter so if it needs a refill i just plug it in. As for my locker one i can plug in the charger or i can just swap batteries with my phone when im heading to the office at the end of the week. I thought it all through lol

Quote: Originally Posted by Avalonthas So if someone knows the equation(s) to determine this it would be appreciated very much so.

"mAh" stands for "milliamp-hours". So you'd just divide the battery capacity (1000mAh) by the current draw (60mA) to get the number of hours the battery would last = 16.67 hours. But since it's already lasted over 4 days, I give up...

You may already know this, but in general, the brighter the LED, the narrower its beam of light. So if you're mounting them in the sides like that, a narrow beam would probably be perfect. If you were to mount them in the base shining up instead, you might want dimmer, wider-beamed LED's.

Cool project, by the way.

Yea i used the 1000/60 and got 16 hours too, but ive been running the setup since the thread was started, and one bar is gone finally off the battery indicator, so i dont know maybe i used the wrong resistor and a lower current is running through the setup resulting in lower mcd and longer runt imes, who knows, i will order a fresh batch when i get a chea source of acrylic which is the last piece i need to start the project.