Large Scale Central

LED help needed

Electronics
#1

I am looking for some help on a lighting project.
I would like to light some buildings on a temporary display.
The thought would be to make a self contained unit containing batteries and an led
light. Figuring I would end up with something the size of a hockey puck or smaller
that I could slide under building(s) as desired. Simple, no wires and a quick setup.

Version 1:
battery, led and off\on switch

version 2:
version 1 + photo cell to turn circuit on and off as needed.

I suspect this is an oversimplification, but you get the idea.

Questions for those who have been there and done that.

  • would 1 led be enough to light a house?
  • what parts would I need to build the lighting units?
  • been debating cutting up a string of chrstmas lights, any thoughts?
  • Where do have you folks been buying electronic parts?

Thanks in advance.

#2

http://www.trainelectronics.com/artcles/LED_light_project/index.htm
http://www.trainelectronics.com/LED_Articles_2007/LED_101/index.htm
two sites that may help

#3

My first thought would be:

(http://barefootelectronics.com/Graphic/photoled.png)

R1 is 10k Transistor on the left is a phototransistor Other transistor a 2N222 or about any NPN transistor you find at Radio Shack or somewhere else White LEDs these days are usually 3v. If you have 3v battery (like 2 C cells) you could get away without putting the other resistor R? in. One LED might not do you. If you have an 8 cell battery for 12 v, you could put 4 leds and no resistor in series and that would light a house quite nicely. Maybe even use one for a porch light. Just be sure they all point the right way. To figure the value of R?, add up the voltage ratings for your LEDs. Usually 3v. So if you want say 3 leds in series, that’s 9v. Subtract that from your battery voltage, say 12 - 9 to get 3. Now divide the difference by the current the LED’s use, usually 20mA (0.02 A), to get 150 ohms. If your battery or LED count differ, just figure the resistor. When you go shopping, they probably won’t have the exact value you figure, so pick the closest. It’s really not very critical. Christmas Lights are usually 3v leds in series. A very inexpensive way to get nice leds. On most sets, you can pull the LED out like the old “Mini Bulb” and take it out of the holder easily. Theory of Operation: In the dark, the left transistor is “off” so current flows through the 10k resistor to the base of the second resistor, turning it on. The second transistor then turns on the LEDs. During the day, light turns the left transistor on and the current from the 10k resistor flows through the photo transistor instead of to the base of the second transistor turning it, and the LED off.

#4

My wife and I went out to eat last night at a nice restaurant, the normal candle where now replaced with the new fake candles, what caught my eye is how bright the new fake candles where.

Enough to illuminate the inside of a structure, all self contained.

Might look around for the new fake lights, try a restaurant supply store or ask someone at your favorite eating places.

#5

LED votive light have both batteries AND on/off switches and are available at most grocery stores or dollar stores. They are not very bright, but you an put a couple of them in a building.

#6

The simplest thing is to take a 9V battery, put a battery connector on it. Attach an LED driver negative to an LED positive to return. The driver will only allow enough current to light the LED. Then disconnect it when you’re through for the day.

#7

When I built my self contained EOT (FRED), I used a 3v lion cell directly. I got lucky though, I could have made the LED for POOF!

If you run android, consider getting ElectroDroid. It is an awesome reference app that will teach you more than enough to run an LED or two.

I found a “light block” at Ollie’s a few months ago: the base had a molded-in 4-AA holder with a 6v light bulb screw socket in between the batteries. It had a frosted plastic housing that provided a soft even glow even from an LED. One of the four soft rubber peg feet was actually mounted to a push switch, when you tapped the entire light it would turn it off/on.

The entire assembled cube was about 4" x 4".

I rewired it to use the 4 AA’s in series->parallel, providing 3v, but twice the current potential. Using ElectroDroid, I figured out which resistor to put between the battery terminal and the switch. Worked great till my son threw it at his older sister and it shattered.

Original Box: 2.99

LED: ~0.40

Resistor: ~0.10

Time: ~6hrs (engineering and manufacturing*)

Value: ~Priceless! - Anything one builds with his/her own two hands can never be accurately valued.

*Have to make it sound important, lol.

#8

Here, check these out: http://www.ebay.com/itm/Salt-Pepper-Shakers-2-Sets-Small-Lantern-Pair-Wood-Commemorative-Pair-NEW-/251228405507?pt=LH_DefaultDomain_0&hash=item3a7e613f03

put a small button battery in the bottom, hot glue the LED (or a few) into the clear top and place one in a house to light.