Originally Posted by
Fibber
Thinking back to the dynamo I had in the '60, it put serious drag on my bike at anything more than 10-12 mph. How is this little Schwinn unit? Do you 'feel' it much?
I never considered using a dynamo myself from my experiences of trying to use one when I was a kid. Back then they were terrible with lots of drag. I remember it was like peddling up hill all the time. A friend purchased one of the Target Schwinn dynamo kits and let me know the drag was not even noticeable after a few minutes of riding. I consequently purchased one myself and was impressed myself with just how little drag was produced by this modern dynamo. I actually enjoy getting out and riding at night with the dynamo engaged knowing I am not burning up batteries in the process.
Originally Posted by
Fibber
Otherwise, agree - nice job.
Thanks!
Originally Posted by
Fibber
What is the current output? Wondering if you could drive the 3W Luxeon head from one of the Element flashlights? I posted the link to Sam's Club two pack of these flashlights a few days ago on the "Is 4 one watt LEDs......" question.
This dynamo like just about all dynamos are designed to power either a single 6-volt 3-watt bulb in the headlight or a 6-volt 2.4-watt bulb in the headlight and a 6-volt .6-watt bulb in the taillight. This equates to about 500mA or .5 amps. The goal is to load the dynamo with 3-watts so the voltage is at or just below 6-volts. My Mag-Lite flashlight draws 350mA so I think it's really rated about 2.5-watts so Mag-Lite rounded it up to 3-watts so it would sell well. I'm not concerned too must as everything works just fine as it is with plenty of light output considering I'm using a dynamo. The problem with using the Mag-Lite flashlight is it's rated to only use 3 volts! It would burn out if I run more than 3-volts DC into it. Considering it also draws less then 500mA the unregulated dynamo is going to pump more than 6 volts into it with too much current as well. That's where the voltage regulator works to keep that from happening. Any voltage produced higher than 3 volts is going to be converted to heat and blown off via the heat sink tab on the voltage regulator. No additional heat sinking is required on the tab of the regulator if the current differential is below 200mA.
A real 3-watt LED is going to draw more than 500mA so technically you would not need a voltage regulator to use it with a dynamo but your still going to need to convert the AC voltage produced by the dynamo to DC for use with the LED and this is going to slightly reduce the current available for the 3-watt LED. The work around for this starts getting complicated as can be seen in this circuit for using 3 1-watt or a single 3-watt LED with a dynamo.
I just wanted to keep everything simple and easy. Using an off the shelf flashlight and electronic parts from Radio Shack allows just about anyone to copy this project.