Powering my LED's
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- davehal9000
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Powering my LED's
I've got like eight 5mm LED's i need to power in a model. I was told I can use a 9v battery but I'm reading the LED's won't last long. What battery combination would be best? Or should I go to hard power instead of batteries?
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What the hell is an Aluminum Falcon????
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- USS Atlantis
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Personally, I'd for a wall-wart (wall mounted, plug in transformer)
Second best - Batteries other than 9v
If the 8 LED's each draw 20ma (standard draw for most LEDs) then the power reserve/lifespan of batteries are as follows (assuming standard alkalines)
9v - 500ma - 3.1 hours
AAA - 1000ma - 6.25 hours
AA - 2000ma - 12.5 hours
C - 6000ma - 37.5 hours
D - 12000ma - 75 hours
Note that as you go up in size, the reserve power increases dramatically
Realize that you'll need multiple batteries to run LEDs - LED voltages run 1.8v (Reds) to 3.5v (whites/blues) - so you'll have to have enough batteries in series to supply at LEAST the voltage needed - then resistors to drop the voltage from what the battery supplies to what the LED needs - overpowering LEDs leads to blow-outs - like blowing a standard lightbulb - no more light
Second best - Batteries other than 9v
If the 8 LED's each draw 20ma (standard draw for most LEDs) then the power reserve/lifespan of batteries are as follows (assuming standard alkalines)
9v - 500ma - 3.1 hours
AAA - 1000ma - 6.25 hours
AA - 2000ma - 12.5 hours
C - 6000ma - 37.5 hours
D - 12000ma - 75 hours
Note that as you go up in size, the reserve power increases dramatically
Realize that you'll need multiple batteries to run LEDs - LED voltages run 1.8v (Reds) to 3.5v (whites/blues) - so you'll have to have enough batteries in series to supply at LEAST the voltage needed - then resistors to drop the voltage from what the battery supplies to what the LED needs - overpowering LEDs leads to blow-outs - like blowing a standard lightbulb - no more light
This assumes all 8 LEDs are connected in parallel. (8 individual circuits, utilizing 3V @20mA and wasting the rest of the voltage at 20mA)USS Atlantis wrote:Personally, I'd for a wall-wart (wall mounted, plug in transformer)
Second best - Batteries other than 9v
If the 8 LED's each draw 20ma (standard draw for most LEDs) then the power reserve/lifespan of batteries are as follows (assuming standard alkalines)
9v - 500ma - 3.1 hours
AAA - 1000ma - 6.25 hours
AA - 2000ma - 12.5 hours
C - 6000ma - 37.5 hours
D - 12000ma - 75 hours
On a 9V source you could hook up two or even three LEDs in series. Each LED would still get 3V drop and 20mA current, but less power would be wasted in resistors. Using a 9V battery as source, LEDs hooked up in pairs with the extra 3V @ 20mA dropped by resistors, the draw from the battery would be cut in half - from 160mA down to 80mA, so you could get around 6 hours that way.
Matching the LEDs exactly to the battery voltage means you can safely omit the resistor altogether - if you have 3 LEDs that run at 3V, you can connect them to a 9V battery with no resistor and waste no power. So you could power 8 or 9 LEDs and only draw 60mA from the battery - and get about 8 hours life. But most LEDs aren't exactly 3.0V at their full brightness - if they were a little over, then you could cut your light output substantially, or if they were a little under, then they might burn out. So I usually like to use a resistor to match the LEDs better to their power source.
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- davehal9000
- Posts: 1800
- Joined: Fri Nov 08, 2002 1:29 pm
- Location: Festvs Mo
- USS Atlantis
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- davehal9000
- Posts: 1800
- Joined: Fri Nov 08, 2002 1:29 pm
- Location: Festvs Mo
- USS Atlantis
- Posts: 2388
- Joined: Sat Sep 08, 2007 6:44 pm
- Location: Galaxy 217, Orion Arm, Sol System, Sol III, 44° 53' N 93° 13' W (Local coordinate system)
- Contact:
- davehal9000
- Posts: 1800
- Joined: Fri Nov 08, 2002 1:29 pm
- Location: Festvs Mo
They came in ziploc bags. I've sent an e-mail out to the guy I got them from to see what he recommends
Warned you we did, but listen you did not! Now screwed we all will be!
Yoda,
The Lost Hope
What the hell is an Aluminum Falcon????
"Just because you don't like something doesn't mean no one else should get to have it."
Penn Jillette
Yoda,
The Lost Hope
What the hell is an Aluminum Falcon????
"Just because you don't like something doesn't mean no one else should get to have it."
Penn Jillette