bigger dynamo bulb question

<[email hidden]> wrote in message
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Quoted message said:

I have a shimano nexus dynamo hub and a bandm oval lamp.
If I put a 5w halogen bulb in it instead of the 2.4w will I get more
light if I go fast enough?

No. You might get more from a 3W one, but any more and your dynamo won't
provide the required current. (assuming your 5W bulb is a 6volt one).

If you put a 12v 5W bulb in it might work (awaits correction) but it won't
light up until you're going at a reasonable speed. See the standard trick
with SONs and putting another front lamp in series.

cheers,
clive

In article <[email hidden]>

Quoted message said:

I have a shimano nexus dynamo hub and a bandm oval lamp.
If I put a 5w halogen bulb in it instead of the 2.4w will I get more
light if I go fast enough?

Possibly not - the more powerful bulb you fit, the closer it is to
short-circuiting the generator, and a shorted generator won't provide
much light.
:-)

Quoted message said:

I have a shimano nexus dynamo hub and a bandm oval lamp.
If I put a 5w halogen bulb in it instead of the 2.4w will I get more
light if I go fast enough?

Is the housing metal or plastic?
I was experimenting with a 10W halogen in an old light designed for a
1W and after a few minutes running it was smoking and the reflector had
welded itself to the bulb.

POHB said:

Quoted message said:

I have a shimano nexus dynamo hub and a bandm oval lamp.
If I put a 5w halogen bulb in it instead of the 2.4w will I get more
light if I go fast enough?

Is the housing metal or plastic?
I was experimenting with a 10W halogen in an old light designed for a
1W and after a few minutes running it was smoking and the reflector had
welded itself to the bulb.

I've run similar in a light intended for 2.4W. It was OK, but the
light seemed to deteriorate with use. When I eventually opened it up,
it was apparent that the bulb had softened the plastic mounting and
moved (presumably under the combined action of gravity and the
retaining spring) away from the focus point of the reflector.

So even if you don't get smoke, you can have problems with too much
heat.

regards, Ian SMith
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Clive George said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have a shimano nexus dynamo hub and a bandm oval lamp.
If I put a 5w halogen bulb in it instead of the 2.4w will I get more
light if I go fast enough?

No. You might get more from a 3W one, but any more and your dynamo won't
provide the required current. (assuming your 5W bulb is a 6volt one).

If you put a 12v 5W bulb in it might work (awaits correction) but it won't
light up until you're going at a reasonable speed. See the standard trick
with SONs and putting another front lamp in series.

The lamp has a built in diode.
Would that have to be removed from the circuit to try this trick?

I get the idea about overheating and frying the mounting.
TerryJ

<[email hidden]> wrote in message
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Quoted message said:

Clive George said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have a shimano nexus dynamo hub and a bandm oval lamp.
If I put a 5w halogen bulb in it instead of the 2.4w will I get more
light if I go fast enough?

No. You might get more from a 3W one, but any more and your dynamo won't
provide the required current. (assuming your 5W bulb is a 6volt one).

If you put a 12v 5W bulb in it might work (awaits correction) but it
won't
light up until you're going at a reasonable speed. See the standard trick
with SONs and putting another front lamp in series.

The lamp has a built in diode.
Would that have to be removed from the circuit to try this trick?

Probably, yes. Personally I wouldn't do it.

cheers,
clive

Quoted message said:

The lamp has a built in diode.

Why does the lamp have a diode? Just curious.
Roger
--
Roger Thorpe

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