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Can anybody remember where the high-power 1.5A 4V bulbs for the oldhams came from? |
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M.E. Foot Soldier
Posts: 127
 
Location: Somerset/Cornwall | We used to get them for the lamps at CSM before the changeover to LED, the ones we had were NARVA brand, see here:
http://www.narva-light.com/pdfs/NARVA_CATALOG_Special_Lamps_DE_EN.p...
the last time we tried to get them from our supplier they wern't available, didnt contact the company directly though, may be worth a try...as for other sources I'm not sure, seems to be very specialist, maybe they were the only company making the 1.5s.
Caving Supplies -might- have a few knocking around |
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| Thanks for that. I did have one about 5 years ago that came from CS, they don't list them anymore however (but they do a 1.25A, which I suppose is a bit better).
I've emailed Narva-Light to see if they can supply any.
Failing that you can get 6v halogen PF bulbs at 10 watts. I wonder if you drove them at 4v instead it would give out about 6w... No idea how you'd work that out! |
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M.E. Foot Soldier
Posts: 127
Location: Somerset/Cornwall | Miles - 15/6/2012 22:35 I wonder if you drove them at 4v instead it would give out about 6w... No idea how you'd work that out! worth a go maybe...thats power engineer stuff fraid I'm just a technician! sure RF can advise...
let us know if you can get the bulbs would be handy for the future
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M.E. Professional
Posts: 499
Location: Stuck in the Chicken | To work out the power consumed, You use W=VA (Watts=Volts x Amperage). Whether it will light up on a lower voltage is another story. As far as I remember, it's dependant on the filament construction as to what Voltage will illuminate it. I have some 6v ones in work, I'll see if I can light up one on a 4v bench supply if it's not mentally busy. |
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M.E. Foot Soldier
Posts: 192
Location: Near Edinburgh, Scotland. | It sounds plausible but not sure if it would work.
While the theory ie power output dissapated would make perfect sense in the situation of resistors not sure if the Bulb filament would be driven at a high enough temp to give out a worthwhile light , don't think it would be as simple as expecting 2/3 of designed light by using 2/3 of the required voltage probably some square root /square in the formula somewhere that would mess things up.
What the formula again ? P=I(squared)xR ? Where P is power output, I is current, R is restance of the Bulb (which you should be able to work out using its designed specs ?) You could then work out the current it would draw for a 4v batt rather its proper 6v by using the 2/3 theory as a smaller current would be drawn by the smaller potential differnce. You could then put the now known I and R back into the formula P=I(squared)xR and see what you get...
Thinking about it a different way ..the other formula is P= V "squared" divided by R
so in the first case V = 6x6=36 and in the second case V = 4x4=16
As R is constant for the bulb in both cases (not perfectly true for temp changes in filament ?) and 16 in less than half of 36 i'd expect a bit less than half the proper power output of the bulb at it real working voltage, this would suggest you get somewhere around 4.5-5w ? But would it be a usable light or just an orange glow i'm not sure. |
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M.E. Professional
Posts: 499
Location: Stuck in the Chicken | Well, you have summed up what I was thinking, but couldn't honestly be bothered typing. In short, I doubt the Filament will do more than glow gently.
It only takes a couple of seconds to try it out though, and I have all the stuff in work to do it, so I'll do that. |
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Location: The Darkside | Miles - 15/6/2012 20:12
Can anybody remember where the high-power 1.5A 4V bulbs for the oldhams came from?
I did have a box of them somewhere, damned if I know where though. I'll have a look later today but haven't seen them in several years.
I also have a early LED bulb conversion somewhere which I think is a a 1 watt side emmiter built into an Oldham bulb case, is that any use for what you are doing?
Caving Supplies might be able to help-
http://www.caving-supplies.co.uk/cgi-bin/psProdSrch.cgi?mode=user&t... |
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M.E. Professional
Posts: 471
Location: North Wales | You could ask EnerSys-Hawker since they still make the lamp http://www.enersys-hawker.com/customerservice/customerservice_uk_local.asp?lang=e
Edited by Manicminer 16/6/2012 08:25
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M.E. Foot Soldier
Posts: 192
Location: Near Edinburgh, Scotland. | NewStuff..my post wasn't inferring there was anything wrong with your own thinking , you posted when i was still typing up so I didn't know yours was there ! :-)
Please post the results as this is something i have been thinking about for a while as Ikea do some very small 12v Halogen bulbs and i was wondering if you could run one by using a Voltage boost cct as the bulbs themselves are very cheap and readily available from my local Ikea 3 miles away.
My thought is though that they are not very efficient on battery life as the desk lamp i have gets extremely hot so must be quite energy inefficient ? Seems a simple fairly robust solution but at the price nowadays of a small LED and a resistor cct would still likely be more efficient than any bulb ?
Here is an old link using led and an old bulb holder http://ukcaving.com/board/index.php?topic=6386.0 .
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M.E. Foot Soldier
Posts: 127
Location: Somerset/Cornwall | Enersys did have a part number for the 1.5 but dammed if I can find it now...
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M.E. Professional
Posts: 471
Location: North Wales | GT DIAGRAM – ITEM LIST
M200101. Headpiece shell
M201121. Bezel ring
M200131. Glass lens
M200411. Sealing channel
M203827. Reflector
M200323. Small bulb socket
M259130. Main bulb 4V 48 Lumen Halogen **
M200130. Small bulb 4V 0.46A
M200383. Prefocus reflector Bush and connection
M203456. Cable 1.59m
M455101. Plastic protection shoe
** dependant upon lamp type and temperature
classification
It will be - M259130. Main bulb 4V 48 Lumen Halogen **
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M.E. Professional
Posts: 499
Location: Stuck in the Chicken | I didn't get time today, work was manic. Should be able to tomorrow before we open. |
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M.E. Foot Soldier
Posts: 127
Location: Somerset/Cornwall | Manicminer - 16/6/2012 17:01 Main bulb 4V 48 Lumen Halogen ** M200130. Small bulb 4V 0.46A M200383. Prefocus reflector Bush and connection M203456. Cable 1.59m M455101. Plastic protection shoe ** dependant upon lamp type and temperature classification
It will be - M259130. Main bulb 4V 48 Lumen Halogen ** yeah it was something like that but the 48 Lumen was 1A, I remember checking that out, thanks though. whats annoying is that I had a pdf with the bulb options, temp. classifications etc. from Oldham on my computer for ages, can't find it now!
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M.E. Professional
Posts: 499
Location: Stuck in the Chicken | Run a search for *.pdf? |
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| Thanks guys 
Some of the science really was beyond me! But I'll be interested to know what you find. Simply put, 6v 10w bulbs are easy to buy, 4v 6w are not. The only thing different between different bulbs is the thickness of the filament, so surely a bulb with a given filiment size should be good for a whole range of volts in / watts out?
I used my new Oldham today at work (instead of my usual Raptor Pro 2), got a few GL16s now. In truth the Oldham, lovely orange glow that it produces, falls a bit short on output really. It was OK, but a little feeble compared to the Raptor. If I could bump it up to 6w I'd be very happy. I prefer the glow of proper halogen, in particular as a pilot. |
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M.E. Foot Soldier
Posts: 127
Location: Somerset/Cornwall | NewStuff - 16/6/2012 21:28 Run a search for *.pdf? tried it, nothing doing...I think the name of the pdf must have been some code. no matter, will give Enersys a bell when I get time in the week |
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| Jagman - 16/6/2012 07:33
Miles - 15/6/2012 20:12
Can anybody remember where the high-power 1.5A 4V bulbs for the oldhams came from?
I did have a box of them somewhere, damned if I know where though. I'll have a look later today but haven't seen them in several years.
I also have a early LED bulb conversion somewhere which I think is a a 1 watt side emmiter built into an Oldham bulb case, is that any use for what you are doing?
Caving Supplies might be able to help-
http://www.caving-supplies.co.uk/cgi-bin/psProdSrch.cgi?mode=user&t...
a box of them you say?
well, if you find them... |
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Location: The Darkside | Yeh I'll give you a shout.
They aren't on the rack charger which means they are safely tucked away in a carrier bag somewhere in the garage..... |
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Rookie
Posts: 33
Location: Burton on Trent | Don't think it will work well Miles. The filament resistance changes dramatically with temperature, much lower when it's cold. So a bulb has a 'sweet spot' where it's hot enough, bright enough and the right resistance. Thank god we've got LEDs now.... |
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6w Oldham Bulbs
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