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mystery bulb

Hi, I have just bought a copper lamp at a boat jumble nasty green but with a lot of effort will make a great headlamp with its ridged glass. Problem (there is always one) the bulb is etched with the number 622 with no voltage it is a small bayonet fitting with a vertical coiled filament supported by a c type filament holder. I have googled with no success 12v hasn't lit it up but that could be the crap wiring. If no info I will replace it with a sbf bus bulb.

Reply to
back to the boats
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Don't you have a friend with a test meter? First check the resistance of the filament & the wiring then check the current flow on 12v and higher voltages.

Reply to
Dave Croft

622 is a standard bulb code for auto electrical retailers, if you cannot find anything on-line or from here, I'll ask our guy on Tuesday.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk

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Reply to
Peter A Forbes

That thought went through my mind as well but google doesn't spit out anything useful with "622 bulb" as a search...

Reply to
Dave Liquorice

Didn't you Google for "622 lamp"? Remember the Blackpool Corporation electrician: "162,000 lamps and not a single bulb".

John

Reply to
John Nice

=== Not quite that easy, I'm afraid.

The difference between the hot (running) resistance and cold resistance as measured with an ohmmeter is of the order of 20 times. i.e., on initial switch-on, about 20 times the running current inrushes. Newish bulbs can withstand this. That's one of the reasons why older bulbs often blow when first switched on (the other is the magnetic force due to the inrush surge which blows the coils asunder)

One way might be to measure and compare the cold resistances of a bulb of known voltage, but they'd have to be of the same wattage, and I understand that this is not known.

I'd start off with a low voltage and step it up, the problem being (1) you'd need a variable supply and (2) how would you know when it is up to its design brightness?

However, as you'd hope that bulbs are rated at standard voltages, you could try stages of 12, 24, 32,50,110 etc. When it blows, go back one step ...

JW² ===

Reply to
JW²

Doesn;t help either, and yes I'm aware of the abscenec of "bulbs" and the things that hold lamps are luminaires.

Reply to
Dave Liquorice

Reply to
Gordy

Everything appears to be "Sold out" but you can hire him to find them for you ;-) Why bother when Google finds them for free!

ttfn

Reply to
Roland Craven

I went through Vince's catalogues with him this afternoon, as I was in Luton getting the wheels rotated on the van, and we could find no reference at all to a 622 bulb, either in old or new books/catalogues.

623 exists, but no 622 as far as we could see.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk

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Reply to
Peter A Forbes

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