litlmh
Newly Enlightened
I was seeing if anyone could help me check these calculations, since I'm not sure whether I'm doing them correctly. I already did a search and found this thread, which helped me a little.
For this flashlight: http://store.advancedmart.com/5wamesiledfl.html
There is a review at FlashlightReviews which speculates that it is using an 8mm 100 mA LED (http://www.powerleds.com/data/pro4.html). Another review measured the current draw at 91 mA, so that seems correct.
Since it's a direct drive flashlight, modifying it to use NiMH batteries means that it needs a resistor in series, right? So here are my calculations:
Since each NiMH battery starts at about 1.4V, 1.4V x 3 = 4.2V
LED operating values: 3.2 V @ 100 mA
4.2 - 3.2 = 1V drop
Using V = IR,
1V drop at 100 mA = 10 Ohm resistor
Does this seem correct? Any help would be greatly appreciated. Thanks in advance!
For this flashlight: http://store.advancedmart.com/5wamesiledfl.html
There is a review at FlashlightReviews which speculates that it is using an 8mm 100 mA LED (http://www.powerleds.com/data/pro4.html). Another review measured the current draw at 91 mA, so that seems correct.
Since it's a direct drive flashlight, modifying it to use NiMH batteries means that it needs a resistor in series, right? So here are my calculations:
Since each NiMH battery starts at about 1.4V, 1.4V x 3 = 4.2V
LED operating values: 3.2 V @ 100 mA
4.2 - 3.2 = 1V drop
Using V = IR,
1V drop at 100 mA = 10 Ohm resistor
Does this seem correct? Any help would be greatly appreciated. Thanks in advance!