1sennafan Posted August 20, 2013 Posted August 20, 2013 Hi I'm trying to educate my self about electronics in general but more so about LEDs. I have a flashlight with 27 white LEDs total. You can run 24 at once or the other 3 at once. The power supply is 3 AAA batteries for 4.5v "NOT" and 2 resistors, a 10 ohm 5% resistor 1/4 watt and a 1.5 ohm 5% resistor 1/2 watt and a push button switch.Batteries have 3.32v at present. When the 24 are on I have 2.96v across the 1.5 ohm resistor and .03 across the 10 ohm resistor and about 1v on the 3 LEDs. When the 3 are on I have no change across the 1.5 ohm resistor and 1.44 across the 10 ohm resistor and about 1.4v on the 24 LEDs. Here's what I thought before measuring voltages, you have 6 LEDs run in series, 4 of those series run in parallel with 1.5 ohm 5% 1/2 watt resistor and 3 LEDs run in series with the 10 ohm 5% 1/4 watt resistor.can anybody confirm if this sounds right or am I completely off base?I am not completely off I don't think but I'm pretty sure I don't have it right. Can somebody maybe explain what's going on here, what I'm not getting? Thanks in Advance
m1ke05 Posted August 26, 2013 Posted August 26, 2013 I think you might be better off going to some type of electronics forums.
thevikester Posted August 26, 2013 Posted August 26, 2013 I think you might be better off going to some type of electronics forums. Nice one Mike...that made me laugh! My question would be, why are you measuring this to begin with? Is your kid in some advanced science class for geniuses? I'm not sure how getting this detailed will enhance your lighting experience...but thats just me scratching my head in the corner, looking at volts and amps only, and that is usually sufficient understanding for this endeavor.
Steven Posted August 26, 2013 Posted August 26, 2013 A typical white LED is about 3V. I don't think any LED will light at just 1V. The typical (cheap) LED flashlights I have seen have all bulbs in parallel, and wired directly to 3 AAA batteries in series, using the internal resistance of the batteries to limit the current.
Ken Benedict Posted August 26, 2013 Posted August 26, 2013 Hi I'm trying to educate my self about electronics in general but more so about LEDs. I have a flashlight with 27 white LEDs total. You can run 24 at once or the other 3 at once. The power supply is 3 AAA batteries for 4.5v "NOT" and 2 resistors, a 10 ohm 5% resistor 1/4 watt and a 1.5 ohm 5% resistor 1/2 watt and a push button switch.Batteries have 3.32v at present. When the 24 are on I have 2.96v across the 1.5 ohm resistor and .03 across the 10 ohm resistor and about 1v on the 3 LEDs. When the 3 are on I have no change across the 1.5 ohm resistor and 1.44 across the 10 ohm resistor and about 1.4v on the 24 LEDs. Here's what I thought before measuring voltages, you have 6 LEDs run in series, 4 of those series run in parallel with 1.5 ohm 5% 1/2 watt resistor and 3 LEDs run in series with the 10 ohm 5% 1/4 watt resistor.can anybody confirm if this sounds right or am I completely off base?I am not completely off I don't think but I'm pretty sure I don't have it right. Can somebody maybe explain what's going on here, what I'm not getting? Thanks in Advance These questions show you have an interest in the Do It Yourself part of lighting. For more information, checkout: http://www.theelectronicshobbyist.com/ and: http://amasci.com/elehob/elehob1.html and: http://www.electronics-lab.com/ Then you could get one of these 50 watt RGB led chips and help us light up some of our displays.
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