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Me, I would wire an ammeter in series with the LED. Then measure the amps. Then, I'd get a constant-current driver that runs that exact current (at that general range of voltage). But then, I'm presuming I have ordinary LEDs which are not ohmic (i.e. do not obey Ohm's Law or random websites in fancy fonts). If I had super-magic ohmic LEDs that mysteriously ...


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3V on the LED is what you'd expect from a white LED. Forget about the 9V supply. Instead use a USB "charger" ie a 5V 1A power supply. This should be much more useful as you'll be able to plug the light on a powerbank, on a cellphone charger in the car, etc. Also the resistor power dissipation will be manageable. Cut a USB cable and connect to the ...


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I think the simplest answer is to use an 'off the shelf' MR16 LED lampbulb such as any of these .... https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=mr+16+12v+led+bulbs+-halogen&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=mr+16+12v+led+bulbs And step up the battery voltage a bit using something like this ... ...


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I have a 9,6v 2000mAh Ni-mh battery ... I need 30 to 60 minutes of battery so if I remember my lessons from high school I have approximately 18 W of power available. Not quite. You have 18 Wh of energy available. (Energy = Power × Time.) So, for a discharge to 50% of capacity (safety margin) you have 9 Wh available. To use that in one hour means your lamp ...


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