# LED spot lights



## gthorpe2 (Jan 20, 2010)

I've been doing some searching and I found a website for LED spot lights. I'm going with a 10mm LED with a 270ohm resistor, and the power supply is a 9v battery. I soldered everything together, but the light is not as bright as I want it.

My questions...

What would make the light bright?

Any other suggestions?


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## The Watcher (Sep 13, 2008)

It isn't the size with leds, that make them bright. It is the mcds. A 5000 mcd would be brighter the a 1500 mcd. Most of the time the more mcds, the more they cost.


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## Otaku (Dec 3, 2004)

Do you have the specs for the LED? Forward voltage and current would help in spec'ing the correct resistor.


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## gthorpe2 (Jan 20, 2010)

This is what's on the back off the LED package...

Intesity: 400 mcd (typical)
Wavelength: 660nm (typical)
Viewing angle: 16 degrees
FW current: 20mA
FW supply: 2.4 V (max)


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## Devils Chariot (May 23, 2007)

gthorpe2 said:


> This is what's on the back off the LED package...
> 
> Intesity: 400 mcd (typical)
> Wavelength: 660nm (typical)
> ...


Yeah thats not very bright. Its more like an power on light.

a bright red led will be about 3000 mcd

and ultrabright white led will be around 15000 mcd


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## Otaku (Dec 3, 2004)

OK, the LED calculator I use sez a 330 ohm resistor is optimal, but the 270 you're using is fine. It may shorten the life of the LED a bit, but not so you'd notice.
The intensity value is only 400mcd (milli-candelas) which is a very dim LED. For spotlights this won't do the job too well. Here's a link to a really bright 10mm blue LED for a good price:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16563

I use these for spotlighting my groundbreakers - they're very bright and the color value is excellent. Here's a good how-to for making spotlights with those LEDs:

http://haunttheyard.blogspot.com/2009/08/led-spots.html


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## gthorpe2 (Jan 20, 2010)

Otaku said:


> OK, the LED calculator I use sez a 330 ohm resistor is optimal, but the 270 you're using is fine. It may shorten the life of the LED a bit, but not so you'd notice.
> The intensity value is only 400mcd (milli-candelas) which is a very dim LED. For spotlights this won't do the job too well. Here's a link to a really bright 10mm blue LED for a good price:
> http://www.goldmine-elec-products.com/prodinfo.asp?number=G16563
> 
> ...


That is the information I'm using for the spotlights!! I will check gold mine out. Now I'm getting the knowledge I need to make these. I went to radio shack today and you would think they know what they are doing, but the guy couldn't answer a question I had, so I winged it... I guess I did pretty good, other than getting the super dim LED. LOL


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## The Watcher (Sep 13, 2008)

Radio Shack is is the McDonald's of electronics. It has sure changed over the years.


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## gthorpe2 (Jan 20, 2010)

Would this work? Would it work with a 9V? What type of resistor would I need?
http://www.radioshack.com/product/index.jsp?productId=3111495


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## gthorpe2 (Jan 20, 2010)

If I got the one on gold mine, What type of resistor would I need? Would the 9V work?


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## KevinS (Sep 30, 2007)

gthorpe2 said:


> Would this work? Would it work with a 9V? What type of resistor would I need?
> http://www.radioshack.com/product/index.jsp?productId=3111495


I strongly recommend this site:

http://led.linear1.org/led.wiz

It will provide you with the proper resister values and designs for any number of LEDs.


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## hedg12 (Jul 6, 2008)

If you use the blue LEDs from Electronics Goldmine with a 9 volt battery, you'd need a 270 ohm resistor.


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## heresjohnny (Feb 15, 2006)

I use ebay and buy ultra bright LEDs in bulk. For example, http://cgi.ebay.com/NEW-50ct-5MM-10000MCD-Ultra-Bright-Led-Blue-Brightest_W0QQitemZ270526559594QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efca3b56a will give you 50 5mm 10,000mcd ultra brights for $6.89. This will give you 50 leds for what it would cost to get about 4 from electronic goldmine. Search on ebay for 'ultra bright led' for a big selection.

And I have found the 5mm leds work better for spots than 10mm. 5mm gives you a nice clean circle of light, the 10mms I have used is not nearly as clean. Plus you can squeeze more 5mm leds into the same space.


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## steveshauntedyard (Nov 16, 2008)

Does anyone know how to do it with AC and have all the spots hooked to one zip line so they can all be on a timer and not have to plug a 9V into turn them on every time? I really want to do LED spots but my yard is up for the whole month of October and I would hate to have to plug in 20 9V batteries every night.


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## The Watcher (Sep 13, 2008)

steveshauntedyard said:


> Does anyone know how to do it with AC and have all the spots hooked to one zip line so they can all be on a timer and not have to plug a 9V into turn them on every time? I really want to do LED spots but my yard is up for the whole month of October and I would hate to have to plug in 20 9V batteries every night.[/QUOT
> 
> If you buy 12 volt leds you can put them on a landscape transformer. I am not sure if you could reduce the power from 12 volts to use on stand leds or not. Maybe one of the others will have that answer. I just went on and switched to reguar landscape lights, and bought the bulbs for them.


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## paulcav151 (Nov 15, 2009)

gthorpe2: here is a link to a calculator for LEDs and resistors, and a ton of info to supplement your research.
http://wolfstone.halloweenhost.com/Lighting/litlec_LEDCalc.html#CalculatorForLEDsInSeries


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## heresjohnny (Feb 15, 2006)

The Watcher said:


> steveshauntedyard said:
> 
> 
> > Does anyone know how to do it with AC and have all the spots hooked to one zip line so they can all be on a timer and not have to plug a 9V into turn them on every time? I really want to do LED spots but my yard is up for the whole month of October and I would hate to have to plug in 20 9V batteries every night.[/QUOT
> ...


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## Warrant2000 (Oct 8, 2008)

Last season I bought some LED's from Radio Shack, soldered some lead wires to it, and experimented with batteries. Using 2 AA's, I could power a white and red led. Sorry, I'm at work and don't have the specs, but they were not very bright. I made 4 of these to go into my 4 spider sacs - of course I forgot to put them in on Halloween night... I did not use a resistor.

My question is, what configurations would need a resistor? Does it impact battery life?

Disclaimer: I'm electronically stupid, but trying to get smarter. Thanks!


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## heresjohnny (Feb 15, 2006)

Warrant2000 said:


> Last season I bought some LED's from Radio Shack, soldered some lead wires to it, and experimented with batteries. Using 2 AA's, I could power a white and red led. Sorry, I'm at work and don't have the specs, but they were not very bright. I made 4 of these to go into my 4 spider sacs - of course I forgot to put them in on Halloween night... I did not use a resistor.
> 
> My question is, what configurations would need a resistor? Does it impact battery life?
> 
> Disclaimer: I'm electronically stupid, but trying to get smarter. Thanks!


First of all, the LEDs you got from RadioShack were most likely low mcd LEDs, i.e. not bright. Normal LEDs have a diffused (i.e. cloudy) cover which will make the whole LED glow. Ultra brights have a clear casing and typically only put out a narrow beam of light from the end.

I have used 2 AA batteries to power 2 LEDs for eyes many times. Each AA battery will basically give you 1.5 volts, so using 2 will give you 3 volts which is pretty safe for powering a couple LEDs.

Try the calculator posted earlier to determine if you need resistors. Too high a resister and the LEDs will not be as bright. Too low of a resistor and you will shorten the battery life and maybe burn out the LED.


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## gthorpe2 (Jan 20, 2010)

I just purchased some LEDS at the shack today, and I think I got what I needed... I will post later today or tomorrow what the turn out was. Thanks everyone for your help!!


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## Otaku (Dec 3, 2004)

heresjohnny said:


> Try the calculator posted earlier to determine if you need resistors. Too high a resister and the LEDs will not be as bright. Too low of a resistor and you will shorten the battery life and maybe burn out the LED.


Yep. One way to know if your values are too low would be if the LED is glowing a different color than you expect, like a green LED glowing orange. A hot, or even a warm, LED usually means the resistor is too low.


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