Dynamo lights

[Joe24]

Ive got a set of dynamo lights(thanks MacB) and so far, i can get the rear one to work, but not the front.
The bulbs are new(i popped the back one by putting the dynamo on the rear wheel, thought the rear light was bright then it went out anyway, i can get the rear one to work, but not the front.
So what do i do? They not on the bike yet, so i dont know if that will make a difference? Ive tried grounding the front light to the dynamo bracket, which is what the rear light is attached to, but that stops the rear one coming on.
Ive tried running a grounding wire to an earth we have, that doesnt get it to light up.
WTF am i doing wrong
Im only spinning the dynamo by hand though when i do that, so i dont know if it needs to spin faster for it to sort of light up.
Ive put the bulb in the back light, it glows slightly. Ive put the rear bulb in the front, and that doesnt spark up.

And the next question, what do i put in before in the bulbs, to stop them blowing when i go down hill?

Last question, ive got a carbon fork, where do i ground the front light? Guy in bike shop i got the bulbs from suggested the handlebars.

My front light(not sure if i will use this one, think i will do) is now very very very shiny Its lovely.
Im making up a new mount for it, which goes from the brake bolt, then the lamp clamps onto there.

So can anyone offer any advice?

 

[Jonathan M]

Joe, more info mate. Type of lights, dynamo etc. I've got a Basta Pilot LED dynamo light mounted on a carbon fork running off a Shimano Nexus hub dynamo and that doesn't need grounding anywhere.

 

[Joe24]

Joe, more info mate. Type of lights, dynamo etc. I've got a Basta Pilot LED dynamo light mounted on a carbon fork running off a Shimano Nexus hub dynamo and that doesn't need grounding anywhere.

Its an old bottle dynamo, with 2 old lights.
Thats about all i can tell you.
Take bulbs, not LEDs

 

[Jonathan M]

When I had one of these, a long long time ago, it was grounded by there being a small screw from the bracket & through into the frame (rear seat stay).

 

[Joe24]

When I had one of these, a long long time ago, it was grounded by there being a small screw from the bracket & through into the frame (rear seat stay).

And what happened to the one on the front? Did it go straight back to the rear?

 

[Rohloff_Brompton_Rider]

you can get led replacement bulbs, i.e., leds in a bulb package. you need to get a return path via the casing, this can be via some steel on the frame. i think the old dynamo's used to need a voltage regulator.

 

[Jonathan M]

And what happened to the one on the front? Did it go straight back to the rear?

Yes. IIRC then the wires ran to the rear light and the front, both earthed through the dynamo bracket.

 

[Joe24]

Yes. IIRC then the wires ran to the rear light and the front, both earthed through the dynamo bracket.

Okey dokey. Ill have to shove it on the bike, and try that out.
So, if i leave how the rear light is wired up, then wire the front light, with a return wire, to the light bracket, then put that screw onto the frame to earth it?
If i ran a wire up to the rack mount, and earthed it onto that, would that still work by the way?

 

[Jonathan M]

Ermm, maybe. You're asking me to go back maybe 25 years since I last pratted around with a bottle dynamo, so I'm bowing out here and leaving you in the hands of someone who truly knows what they're talking about.

 

[RedBike]

Front lights are normally very simple. There's just two connections a +ve and -ve.
The -ve is often connected through the frame, although there's no reason why you can't just use a wire.

Daft question but the light isn't switched off is it?

 

[Joe24]

Front lights are normally very simple. There's just two connections a +ve and -ve.
The -ve is often connected through the frame, although there's no reason why you can't just use a wire.

Daft question but the light isn't switched off is it?

Its not got a switch
Its got one wire, which goes into the plastic mount, by the bulb screwing it.
There just is no negative.
The annoying thing is, it is simple. A wire, going from the bottle dynamo to a bulb, how is that hard.
Ill put it on the bike, and wire it up that way, and see how it goes.

What needs to go before rthe bulbs to stop them going when i go down hill? Is it a diode, and if so, how do i know which one to get?

 

[RedBike]

Its not got a switch
Its got one wire, which goes into the plastic mount, by the bulb screwing it.
There just is no negative.
The annoying thing is, it is simple. A wire, going from the bottle dynamo to a bulb, how is that hard.
Ill put it on the bike, and wire it up that way, and see how it goes.

What needs to go before rthe bulbs to stop them going when i go down hill? Is it a diode, and if so, how do i know which one to get?

There must be a negative, without this the light can't work.

The mounting screw probably acts as the -ve
Just take the +ve AND the -ve wires from the dynamo and connect them BOTH to the light / mounting screw.

 

[Rohloff_Brompton_Rider]

the dynamo casing is the '-tive'. that's why there is only one wire. the steel of the bike is used as the return path (-tive). as i remember these things do need regulating or you will be blowing bulbs forever at top speeds.

 

[Joe24]

the dynamo casing is the '-tive'. that's why there is only one wire. the steel of the bike is used as the return path (-tive). as i remember these things do need regulating or you will be blowing bulbs forever at top speeds.

There is no steel on the bike
How do i just put the negative on the light mount, the forks are carbon
So its got to go back to the bike somewhere.
The negative for the front is the whole casing and mount, i already know that
but can i put the negative for both lights so close to each other?

 

[Rohloff_Brompton_Rider]

just run some speaker wire to front light bolt then..duhhh!!! lol