I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

Cheers,
Rick

On Thu, 4 Oct 2007 10:24:38 +0100
"R D S" wrote:

I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

Not really. Although a 12volt bulb is unlikely to be damaged by having
6 volts across it, 6 volts will not get the filament hot enough to
give much light. I'm assuming this is an incandescent bulb.

To get advice on sources for your bulb, you'd need to say what kind of
fitting it is, or, better, post a picture.

R.

In an earlier contribution to this discussion,
R D S wrote:

I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And
if so what wattage would be best?

My understanding of bulbs is that electricity passes through the
filament, it gets hot and glows, so there would surely be
interchangeability, is this about right?

Cheers,
Rick

At a very rough approximation, if you feed a 60w 12v bulb with 6v it will
consume about 15 watts.

However, this is pretty crude because the filament will not get as hot as
it's supposed to - and its resistance changes quite a lot with temperature -
so God knows what you'll *actually* get.

In any case, the chances of getting much useful light out of it are slim
because, at a lower temperature, most of the output will be in the form of
infra-red rather than visible light.
--
Cheers,
Roger
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"R D S" wrote in message
...
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is
this
about right?

Cheers,
Rick

Mail order?

www.cpc.co.uk is good in my experience

On Thu, 4 Oct 2007 09:24:38 UTC, "R D S" wrote:

I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

No. 6 volts is only half the 'pressure' of 12 volts, so only half as
much current flows. You'll only be putting a quarter of the power into
the bulb.

Tell us more about these bulbs you can't get; perhaps post a picture,
and what's written on them.

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

In article ,
R D S wrote:
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if
so what wattage would be best?

My understanding of bulbs is that electricity passes through the
filament, it gets hot and glows, so there would surely be
interchangeability, is this about right?

To make an efficient bulb the filament has to glow at a specific
temperature - and this is achieved by the design of the filament. And the
resistance changes dramatically from cold to hot. Two lamps with the same
nominal resistance when hot will have very different filaments according
to the voltage.

--
*Virtual reality is its own reward *

Dave Plowman London SW
To e-mail, change noise into sound.

R D S wrote:
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

Cheers,
Rick


Try a motor cycle dealer. You certainly *used* to get 'bikes with 6v
electrics. a 12V bulb will do nothing useful.

Andy

In article ,
"R D S" writes:
I use 6v bulbs, 15 Watt.

What lamp base?

CPC have an H3 one:
http://cpc.farnell.com/jsp/search/pr...sp?sku=LP01532
"available until stocks exhausted"

Here's a picture of an H3 bulb (albeit not the one above)
http://cpc.farnell.com/productimages...0396906-40.jpg

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Oct 4, 10:24 am, "R D S" wrote:
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

Cheers,
Rick

These any good?

http://search.ebay.co.uk/search/search.dll?
sofocus=bs&sbrftog=1&catref=C6&from=R10&_trksid=m3 7&satitle=6v+15w+-
supply

cheers,
Pete.

"R D S" wrote in message
...
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if
so
what wattage would be best?

As everyone else has said, "no", and "what type of cap?".

http://www.vehicle-wiring-products.e...ting/bulbs.php

shows a few types, but the only 6V 15W shown is a festoon type.

A pleasant enough firm to deal with, too.


--
Kevin Poole
**Use current month and year to reply (e.g. )***

"Autolycus" wrote in message
...

"R D S" wrote in message
...
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if
so
what wattage would be best?

As everyone else has said, "no", and "what type of cap?".

http://www.vehicle-wiring-products.e...ting/bulbs.php

shows a few types, but the only 6V 15W shown is a festoon type.

A pleasant enough firm to deal with, too.

Thanks all, I got them from a bike dealer last time but they were the wrong
wattage and were a bit dim (i'll do the jokes).

I have some on order and will get the details from the bulb when they come
in.

It is a bayonet type with one terminal on the base.

Cheers.

In message , Sparks
writes
"R D S" wrote in message
...
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability,
is this
about right?

Cheers,
Rick

Mail order?

www.cpc.co.uk is good in my experience

IIRC he's in Lancs - prolly not too far from Preston

--
geoff

In message , R D S
writes
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

a 12v one might glow weakly ...

look on the RS or CPC website


--
geoff

On Sat, 06 Oct 2007 00:03:14 GMT, geoff wrote:

In message , R D S
writes
I use 6v bulbs, 15 Watt.

I struggle to get hold of them locally, could I use a 12v bulb? And if so
what wattage would be best?

My understanding of bulbs is that electricity passes through the filament,
it gets hot and glows, so there would surely be interchangeability, is this
about right?

a 12v one might glow weakly ...

look on the RS or CPC website

One point not taken into account so far. A tungsten filament has a +ve
temp coefficient and the resistance will be far too low if it is on a
lower than design supply. This makes it difficult to estimate how a
12v bulb will work on 6v.