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  #101  
Old 09-14-2009, 07:56 AM
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Shreadvector Shreadvector is offline
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My LEDs are these:


http://www.pinballlife.com/index.ph...1174&parent=192

http://www.ablazelighting.com/index...ge=led-lighting

Marked on the base with "6.3 VAC" and from what I've read, I do not think they will 'burn out' with a 12 volt dc power source.


Quote:
Originally Posted by LeeR
Note: If you are going to use 12V source, get the 12V models of the bayonet base LEDS. While the experiment proved safe, the 6V models of LEDs are overdriven at 12V and may not last very long. The worst aspect of this is that they will draw more current, since their limiting resistor is sized to provide nominal operating current at 6V, and not at 12V.

As an example, I used a Radio Shack LED in my Elctron Bean controller, which needed a limiting resistor. For 6V, I used a 100 Ohm resistor (110 was best choice, but I only had 100 -- well within tolerance). For 12V, I would have needed a 470 ohm. This was based on a forward voltage of 3.2-3.8 V, and suggested operating current of 20mA.

I'd use the bayonet-base LED lamps in the future, but if you want to play with LEDs and resistors, check out www.ledcalc.com
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  #102  
Old 03-30-2010, 09:10 PM
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BEC BEC is offline
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An update on this. I ordered eight of the lamps Fred links to just above, from the source he linked to (the shipping was more than the cost of the eight lamps at 69 cents each). They arrived yesterday and I proceeded to try them out in a little-used Electron Beam. One of the red ones was intermittent (I'll contact the seller about that). The other red one and the clear ones all gave me current draws on continuity indications between 30 and 38 mA on fairly fresh AAs. They are plenty bright.

Now that EB and my original Solar Launch Controller are Q2G2-safe with much less hassle than the LED mod I did to another EB, but since the lamp protrudes from the EB and is quite a bit smaller in diameter than the hole it's in, it feels a little precarious. The Solar controller's lamp well is much deeper, so no issue there.

On a semi-related note, I also recently purchased a Pratt Hobbies FullBoost handheld controller, which uses EIGHT AA cells. It uses a beeper and draws very little current, but a Q2G2 on 12V fires INSTANTLY when you push the button .
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