RipplesOfLife
Newly Enlightened
For some time I have been using homemade White LED (5 mm or 10 mm) bulbs in my old generator incandescent bicycle light and experimenting with them.
I started with using 10 mm LEDs cause they were a perfect fit and they had good throw. I tried two kinds, 60,000 - 80,000 mcd and 80,000 - 100,000 mcd. The 60K had a better beam spot. The 100K out throws the 60K, but you can see the bond wires/yellow layer in the beam spot and because of this it gives a warmer light.
Then I tried 3 x 5 mm 25,000 mcd LED bulbs. Gives a bit more flood light than using just one 10 mm, but less throw.
And then, I tried a 7 x 5 mm LED bulb (6 white 40,000 mcd + 1 red 14,000 mcd). This one was quite interesting. After using only white LEDs for bike lighting for some time, I realized that they won't light up stop signs/tail lights/anything red. Plus, I often can't distinguish road and grass because the contrast is quite poor from the LED lighting, especially when the road is the black type and not gray. And then there's always that ghostly feel from the lighting.
So that's when I decided to make a bulb that will give more light and have a warmer light. But unfortunately, the 7 x 5 mm bulb did not do that. Did not give too much more overall light, and instead of a warmer white light, I got purple white! I think I should have used an amber or yellow LED.
I removed two of the white LEDs (the yellow dots indicate the ones removed) thinking that would make it brighter... Nope.
I switched to LED because it's more reliable, but mostly because I wanted to have some light when I stopped pedalling. Which means I have a little capacitor power station. More about that later.
Here's the funny thing about my ... journey ... of LED bulbs, I basically satisfied my goal of having light when not pedalling by using one 10 mm LED at the beginning. And now, by having 7 LEDs, that's 7 x 30~ mA = about 210 mA. That's almost as much as what the incandescent bulb took. So, the LED dims when I stop. But one interesting thing about this 7 LED bulb is that when I stop, all the white LEDs dim, but the red LED stays on. I know, it's nothing big, just interesting to see.
Aside from using 5 mm and 10 mm LEDs, I had mounted (tied) my 1 watt Luxeon headlamp and tried it out too. A lot of light, but still has some of the short comings of white LEDs like contrast of object colors. The contrast is better, but not by too much. Oh, one big problem with the other LEDs was that because they don't throw that much or light up objects as much, it was hard to tell if there were people coming my way or ahead of me. That wasn't too much of a problem with the headlamp. But still, can't beat an olde incandescent.
A funny thing happened as I was testing my 7 LED bulb in the park the other day. Another cyclist was coming from behind me. As my light could barely light much of the road, his light lit up the road in front of me, the signs in front of me, and the trees and grass in front of me. When he passed me, it was all dark again.
I think he had an HID?? light. The light was a bit blue.
And now just recently, I got a warm white 3 watt Prolight emitter rated 3.99V, 700mA Max. Now here is were I have some questions.
The generator on my bike is a 6V. Goes through a bridge rectifier connected to a 5.5V 1F capacitor.
Initially I put three parallel resistors totalling a bit more than 8 ohms in series with the emitter. From calculations, that will underdrive it. It wasn't bright, dimmer than my 1 watt headlamp. Also I do not have a reflector for it, though, right now I'm using the one from my headlamp, yup, it kind of fits.
Ok, now I modified my Kinderegg powerstation (http://www.candlepowerforums.com/vb/showthread.php?t=121116) to have two capacitors in series. I always felt that the reason why my light got dimmer when I stopped was because the capacitor was rated 5.5V but when I calculate resistors, I would use 6V. Also I noticed that as I turned the wheel, the 3 watt would flicker and may be due to the capacitor's voltage rating.
Well..., that did not make the Prolight 3 watt light any brighter. So I changed the resistors to four in parallel totalling 2.something ohms. It got a bit brighter, but still dim compared to my 1 watt headlamp.
Now, here's the thing. I just read about bicycle generators and it seems they have an output current limit of about 500 mA. (At least affordable ones, like mine.)
"My knowledge in electronics is limited, I know some basics, but not too much."
Ok, I don't think I can safely direct drive it. I've burned an LED before by just using a resistor value that was too low.
What I need is something to bring the voltage down and bring the current up. Any suggestions?
Also, the emitter I have is the lamber type, reflector? or collimator? The reflector from my headlamp seems to be ok for it.
*edit*
Oh yeah, the obvious answer would be a step-down transformer between the generator and bridge rectifier. But is there a more efficient way? Would this raise the current that much?
I started with using 10 mm LEDs cause they were a perfect fit and they had good throw. I tried two kinds, 60,000 - 80,000 mcd and 80,000 - 100,000 mcd. The 60K had a better beam spot. The 100K out throws the 60K, but you can see the bond wires/yellow layer in the beam spot and because of this it gives a warmer light.
Then I tried 3 x 5 mm 25,000 mcd LED bulbs. Gives a bit more flood light than using just one 10 mm, but less throw.
And then, I tried a 7 x 5 mm LED bulb (6 white 40,000 mcd + 1 red 14,000 mcd). This one was quite interesting. After using only white LEDs for bike lighting for some time, I realized that they won't light up stop signs/tail lights/anything red. Plus, I often can't distinguish road and grass because the contrast is quite poor from the LED lighting, especially when the road is the black type and not gray. And then there's always that ghostly feel from the lighting.
So that's when I decided to make a bulb that will give more light and have a warmer light. But unfortunately, the 7 x 5 mm bulb did not do that. Did not give too much more overall light, and instead of a warmer white light, I got purple white! I think I should have used an amber or yellow LED.
I removed two of the white LEDs (the yellow dots indicate the ones removed) thinking that would make it brighter... Nope.
I switched to LED because it's more reliable, but mostly because I wanted to have some light when I stopped pedalling. Which means I have a little capacitor power station. More about that later.
Here's the funny thing about my ... journey ... of LED bulbs, I basically satisfied my goal of having light when not pedalling by using one 10 mm LED at the beginning. And now, by having 7 LEDs, that's 7 x 30~ mA = about 210 mA. That's almost as much as what the incandescent bulb took. So, the LED dims when I stop. But one interesting thing about this 7 LED bulb is that when I stop, all the white LEDs dim, but the red LED stays on. I know, it's nothing big, just interesting to see.
Aside from using 5 mm and 10 mm LEDs, I had mounted (tied) my 1 watt Luxeon headlamp and tried it out too. A lot of light, but still has some of the short comings of white LEDs like contrast of object colors. The contrast is better, but not by too much. Oh, one big problem with the other LEDs was that because they don't throw that much or light up objects as much, it was hard to tell if there were people coming my way or ahead of me. That wasn't too much of a problem with the headlamp. But still, can't beat an olde incandescent.
A funny thing happened as I was testing my 7 LED bulb in the park the other day. Another cyclist was coming from behind me. As my light could barely light much of the road, his light lit up the road in front of me, the signs in front of me, and the trees and grass in front of me. When he passed me, it was all dark again.
I think he had an HID?? light. The light was a bit blue.
And now just recently, I got a warm white 3 watt Prolight emitter rated 3.99V, 700mA Max. Now here is were I have some questions.
The generator on my bike is a 6V. Goes through a bridge rectifier connected to a 5.5V 1F capacitor.
Initially I put three parallel resistors totalling a bit more than 8 ohms in series with the emitter. From calculations, that will underdrive it. It wasn't bright, dimmer than my 1 watt headlamp. Also I do not have a reflector for it, though, right now I'm using the one from my headlamp, yup, it kind of fits.
Ok, now I modified my Kinderegg powerstation (http://www.candlepowerforums.com/vb/showthread.php?t=121116) to have two capacitors in series. I always felt that the reason why my light got dimmer when I stopped was because the capacitor was rated 5.5V but when I calculate resistors, I would use 6V. Also I noticed that as I turned the wheel, the 3 watt would flicker and may be due to the capacitor's voltage rating.
Well..., that did not make the Prolight 3 watt light any brighter. So I changed the resistors to four in parallel totalling 2.something ohms. It got a bit brighter, but still dim compared to my 1 watt headlamp.
Now, here's the thing. I just read about bicycle generators and it seems they have an output current limit of about 500 mA. (At least affordable ones, like mine.)
"My knowledge in electronics is limited, I know some basics, but not too much."
Ok, I don't think I can safely direct drive it. I've burned an LED before by just using a resistor value that was too low.
What I need is something to bring the voltage down and bring the current up. Any suggestions?
Also, the emitter I have is the lamber type, reflector? or collimator? The reflector from my headlamp seems to be ok for it.
*edit*
Oh yeah, the obvious answer would be a step-down transformer between the generator and bridge rectifier. But is there a more efficient way? Would this raise the current that much?
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