Originally Posted by
Tourist in MSN
If you go fast down a hill you can blow out incandescent bulbs. I used to run zener diodes across it so that if voltage went above about 8 volts, the excess power would be drained off through the diodes.
Thank you. Downhill will I think be the only time this bike will go fast. It is an old Schwinn that weighs a ton.
Originally Posted by
unterhausen
It really depends on the load. If it's a dead short, zero volts, if it's open circuit, 100 volts.
If it's the correct size light bulb then I would expect around 6v.
Open circuit is how I was getting the 1.5 volts. Seems like this may be a dead dynamo.
Originally Posted by
steelbikeguy
If you are going 10mph or more, I'd expect to see over 6VAC if there is no load connected.
How much current do you get from the dynamo when it is running at 10mph or so??
Steve in Peoria
I haven't measured current. When the lights didn't work I just went to voltage checks and confirming that I had good continuity from the output terminal to the contact at the end of the lamp as well as ground continuity from the dynamo to the case of the headlight. My open circuit voltage test producing 1.5 vac was done by spinning it up to an estimated RPM of what I would expect at the tire with a cordless drill. I didn't want to spin it at high RPM with the drill because I didn't want to tax the bearings or sleeves with whatever 54 year old lubrication that may be left.
Thanks all for all the ideas. I had one of these on a bike when I was a kid, but not since. I just always assumed these were DC generators and didn't realize they were AC.