I still cant seem to find replacement bulb for my multi-function Christmas-tree bulbs.

Naturally, the original box and instructions have long been thrown away.
There is a label stuck around the wire saying " replacement bulb: 7volt 8.4watt"

Is there any look-up table to convert this to one of the new codes "eg: w5" which appear to be the
new way bulbs are identified?

Brendan
--
Rayleigh, Essex (51:34N 0:36E 30m asl)
Castle Point Astronomy Club http://www.cpac.org.uk



"Nick Smith" wrote in message
...
Had this problem myself last week - What I did with my 40 bulb (6 volt bulbs) set was to
take
a small sample, say 3 bulbs, run each of them of a variable bench supply at an accurate 6
volts
(measured at the bulb) and with an ammeter in series and measure what the current being
drawn is. Mine were all about 125 mA, which also gives the wattage by calculation.
Be careful not to measure the fuse bulb, and be sure to have one in circuit to avoid the
domino effect.

Then a trip down to the shed armed with this electrical info to see what the bases look
like
and the choice is made. Our Tesco had a good selection of spares (99p for 5).

Alternatively there is an (expensive) website, www.sparebulbs.com which has an online
catalogue if you know the part number (usually on the box).

Nick




"Set Square" wrote in message
...
In an earlier contribution to this discussion,
steve wrote:

"steve" wrote in message
...
A seasonal question certainly...
As usual, dragging the xmas lights out of their box for their annual
outing - some of the bulbs are blown and the spares have long since
gone walk about. The boxes have also been chucked so can`t find what
the voltage/wattage is either :-(
How do you normally calculate what wattage/voltage bulbs to use? I
went to B&Q and had a whole host to choose from, 12v, 2.4v, 1.1W,
0.96W etc.... I`ve got three sets, one looks to be mains voltage (no
transformer), the other is low voltage (24v), but not sure what
wattage bulbs are needed. One other set is multi function, but can`t
tell if its low voltage or not . Where do I start?

Also I forgot to mention that all the manufacturers seem to have
slightly different connector sizes.
I tried some replacement bulbs I thought would be generic from B&Q
but they didn`t even bl**dy fit !

Grrr - hating xmas already
Steve

If you take a bulb out and look at it through a strong magnifying glass, it
may have the voltage and wattage stamped on it.

If a set runs off the mains - with no transformer - the bulbs are invariably
connected in series - usually either 20-off 12v bulbs or 12-off 20v bulbs.
If you divide 240 by the number of bulbs, that will tell you the voltage of
each bulb. Unfortunately, it doesn't tell you the wattage - which determines
the filament resistance. If you fit a bulb which has the wrong resistance,
the voltage won't be shared out properly across all the bulbs. If you've got
a multi-meter with a sensitive resistance measuring facility, measure the
resistance of a good bulb, and try to get a replacement with the same
resistance. [Measured cold, of course - which won't be the same as the
running resistance but should give a comparison].
--
Cheers,
Set Square
______
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