DANMAS wrote:
>
> In a message dated 4/29/98 3:20:22 PM Eastern Daylight Time,
> paul.hunt1@virgin.net writes:
>
> > 12v 2.2W lamps/light bulbs are commonly available in the UK.
>
> Paul,
>
> Buying a 12 volt light bulb is like buying a 2 X 4! Just as a 2 X 4 is not
> actually 2" X 4", a 12 volt light bulb may not be rated at 12 volts. 12 volts
> is the nominal value, just as 12 volts is the nominal value for the voltage of
> a car battery. In good conditiopn, a car battery will produce 12.6 volts. As
> an example of light bulb ratings, take the very common 1157 bulb, used in
> almost every American car (at least in the older American cars). It is a dual
> filament bulb, one filament rated at 27 watts and the other filament rated at
> 8 watts. If you look up the manufacturers specifications, you will find that
> the brighter filament is rated at 2.1 amps at 12.8 volts, while the other
> filament is rated at 0.59 amps at 14 volts.
>
> If you go to an auto parts store to buy one, if it says anything at all on the
> package, it will say 12 volts. For 99.00% of applications, that is close
> enough. If you really need to know how much current it draws, you will have
> to get the spec sheet and find out at what voltage the 27 and the 8 watts were
> rated at. Then you will need to know what voltage it will be seing n your
> application, which is very hard to do, as the voltage in a car varies from as
> low as 11+ volts to as high as 15 volts. In a car with a properly
> functioning alternator, the voltage will be around 14 volts most of the time.
>
> If you go to the manufacturers spec sheet, as the gentleman who raised the
> question did, you may find the 12 volt, 2.2 watt bulb you have is actually
> rated at 14 volts. Or 12.8. Or 16. Or whatever.
>
> Dan Masters,
> Alcoa, TN
>
> '71 TR6---------3000mile/year driver, fully restored
> '71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
> http://www.sky.net/~boballen/mg/Masters/
> '74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
> '68 MGBGT---organ donor for the '74
I just go by what it says on the case - 12v 2.2w
PaulH.
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