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I'm not sure if this is right site for this, but couldn't find better.

I've been given an task to create something that has light intensity like police beacon. I need it to be cheap, so I'm looking at dealextreme.com LED emitters , but there aren't any good user experience videos.

I don't know if the LEDs are right for this and how should I pick right one from these LEDs.

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    \$\begingroup\$ Do you need it to flash ? \$\endgroup\$ – Rocketmagnet Sep 15 '12 at 22:33
  • \$\begingroup\$ Do you need a spot light, or what is commonly referred to in the US as a "light bar." \$\endgroup\$ – rdivilbiss Sep 15 '12 at 23:05
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Maximising brightness:

Brightness is a function of amount of light and area illuminated.

  • More light = more brightness.

  • Less area = more brightness.

So

For more light obtain as many lumens as you can afford.

For less illuminated area use LEDs with low "radiation angle" or "cone angle".

Lenses:

If that is not bright enough you can use a lens or reflector.
Many companies provide lenses for LEDs.
Deal Extreme have a range here

Effect of colour: Note also that brightness is related to eye response to colour - yukky yellow green is about the best colour for optimum eye perceived brightness - but if you want a specific colour this is not much help in optimising brightness.


Related: Mind plasticity add on for the ever young:

Lime Green is close - Lime Green Fire Engine from here - BUT more recent studies suggest that familiarity is more important than visibility for emergency vehicles.

enter image description here

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  • \$\begingroup\$ Ahh, but why does the lime green fire engine have red lights atop it then? ;-) \$\endgroup\$ – Oli Glaser Sep 15 '12 at 22:03
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    \$\begingroup\$ @OliGlaser Because they got laughed at for for the teal and fuschia lights. \$\endgroup\$ – user3624 Sep 15 '12 at 22:22
  • \$\begingroup\$ What's all this about fire engines? I thought the guy just wanted to flash some really bright LEDs? \$\endgroup\$ – Rocketmagnet Sep 15 '12 at 22:33
  • \$\begingroup\$ @Rocketmagnet - The Feuerwehrwagen was a bonus - aimed at assisting bouncy fun smart and stretchy mental plasticity in aging brains. He said he wanted a bright light "like a police beacon" that may also mean he wanted red or just possibly blue - but maybe not. I mentioned that spectral frequency (aka colour) affects visibility, said that yukky green was about optimum and then decided that a lime green fore engine would help reinforce the point. Seemed like a plan at the time. \$\endgroup\$ – Russell McMahon Sep 16 '12 at 0:12
  • \$\begingroup\$ Yes, but where's the bit where you explain how to select an LED, how to wire it up, and possibly, how to make it flash? I can see a down vote coming... \$\endgroup\$ – Rocketmagnet Sep 16 '12 at 0:22
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It sounds like you would be better of with an of the shelf high-brigtness LED lamp rather than individual LEDs for which you need to make a circuit.

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If you want very high brightness for a split second, then a few seconds to charge it up again, use a camera flash with a timer circuit and a relay. It is really bright and is great for a lightning effegt

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