12v bottle dynamo

[Ian H]

A friend who does charity work with kids in Vietnam is looking for one.  It's to run balcony lights from a trainer at a fund-raising do. 

Any ideas where he might find one?  Anyone got one in a drawer somewhere?

[Ruthie]

You can get one for less than £20 brand new can't you?  If nobody's got one kicking around.

[MikeFromLFE]

Isn't 12v a bit esoteric? Aren't most 6v? I think Nordlicht used to do a 12v one.


Sent from my iPad using Tapatalk

[Ian H]

Isn't 12v a bit esoteric? Aren't most 6v? I think Nordlicht used to do a 12v one.

B+M did as well.  Unfortunately we can only find 6v ones so far.

[Ruthie]

Ah, my mistake, I didn't notice the 12v bit.  They usually are 6 aren't they.

[jsabine]

You might find it easier to source 6V lighting ...

IIRC, the 12V dynamos were priced according to their rarity.

[Ian H]

I don't know any details except the event is in Vietnam.  I suspect the lighting might be in place.

[Exit Stage Left]

Dynamos are actually alternators, so you could feed it backwards through a 220v to 110v transformer. I'd be tempted to  try running a car alternator off the tyre. A simple wooden cradle for the alternator should be easy to fix up, maybe even a belt.
I suspect they have no idea of the wattage of bottle dynamo. A simple permanent magnet 12 volt motor would give more power.

You Tube video.
https://www.youtube.com/watch?v=kVAZIDFMRXY

[Kim]

Dynamos are actually alternators, so you could feed it backwards through a 220v to 110v transformer.

That's not a terrible idea...

I'd be tempted to  try running a car alternator off the tyre. A simple wooden cradle for the alternator should be easy to fix up, maybe even a belt.

That not so much.  A car alternator will need a battery in the circuit to regulate properly, which means you lose the "no pedalling, no power" effect.  Also, they need a surprisingly high RPM on the input shaft.

I suspect they have no idea of the wattage of bottle dynamo. A simple permanent magnet 12 volt motor would give more power.

Indeed.


Alternative approach, since it's for lighting:  Use 6V lights.  Plenty of those designed for lighting bicycles...

[Cudzoziemiec]

Several on ebay but all in US.
http://www.ebay.com/bhp/12v-generator

[PhilO]

If the lighting load is high a bit high, you could also get the 'pedal for light' effect by using the dynamo to switch a relay, and actually power the lights from another source.

I realise this woild be cheating.... 

[Exit Stage Left]

If the lights are LED you'd probably need DC output.

[mrcharly-YHT]

Bridge rectifier would sort that out, albeit with a little flicker.

[Ian H]

Sorry, should have replied.  Someone found a cheap one on the interweb and he's going with that. 

Thanks.