High Tension on Dynamo Lights

[Martin]

I just measured the voltage across an unloaded rectifier-capacitor arrangement, connected to a Shimano DH-3D71 hub:
25 km/h => 50V
50 km/h => 98V
These values are no longer safe to touch and they are backed by sufficient DC current to do harm.
Hmm.. A voltage doubler even produces twice the voltage (100/196V). All this from a dynamo that is rated 6V !

Now "unloaded" is not what we typically do here, but it sometimes happens by accident and the capacitor remains charged for a while with the capability to provide some current even after the dynamo has stopped.

I want to call this into people's minds so we don't get an accident from playing with dynamo lights.

 

[ktronik]

good point!!

its all good fun until someone gets hurt.

better to take steps to make your work safe, than rush into building a project without the right tools...

EX:

A good clean work area, is a safer work area. A anti-static work-matt is a good idea for many reasons. Anti-static wrist-band (hooked to ground) is another good idea & electrical type screwdrivers as well.

A slow 'think before you do' type approach, will get your their in the end, without having to re-do you rush work when it blows.

after each step, check & test what you have done...better to check each step, than 'wip it up' & test @ the end...


rant over

be safe people....

K