Help locating small bulb

Hi knowing many forum members dabble in electronics so I know its maybe a long shot does anyone know where I can obtain a 3V Lilliput bulb ? I have obtained some 6v 50 mA ones but they need to be 3V . I need them for a old mini handheld torch with flex extiontion that uses 2x 1'5v AAA batteriess.

I would be tempted to use a white led....made up into the liliput screw base..

I would be tempted to use a white led....made up into the liliput screw base..

Have you tried BLT  **LINK** Phone them.

Edited By Roger Provins 2 on 21/11/2014 16:20:18

Try Squires 100 London Rd Bognor Regis West Sussex PO22 1 DD. 01243 842424, they also have leds.Ted

Harry , not sure what a Lilliputbulb is but mini mag lite torches use a very small 3v bulb, about 1/8" dia with two prong contact. Easy to buy from many retailers of Maglite torches.

Try www.hobby.uk.com

Cheers Derek.

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Although this not a suitable replacement, it does have a good sketch of the LES base.

If I recall correctly, this is the base used on older Christmas Tree lights.

Sorry, I don't know where to source 3v Lilliput bulbs these days ... but I agree that it would be an ideal thing to update to LED.

MichaelG.

Derek (Magpie) has got the answer .

Neil

Harry

If you only have 3 Volts available, forget the white LED!

LEDs are generally current driven and in most applications are fed (with a voltage) via a resistor. The actual voltage across LEDs varies with the manufacturing technology and the colour, its less than 2 Volts for a red LED but about 4 Volts for white and blue ones.

Another thing to bear in mind is that LED usually give out illumination in one direction whereas an incandescent filament emits light in all directions.

I have seen (but not this Christmas) decorative lighting novelties that consist of a two cell battery holder with about 10 lengths of semi-stiff thin green wires each terminated in a tiny bulb. I think they are intended to be entwined in miniature trees as decoration. They would be a very cheap source of ready wired lighting for models.

Ian P

Extra lines removed after posting

Edited By Ian Phillips on 21/11/2014 21:09:09

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Ian,

Sorry to disagree, but; the world is full of White LEDs running very adequately on [nominally 3volt] coin-cells, and pairs of AA or AAA Alkaline pen-cells.

MichaelG.

That was a real oops on my part!

White LEDs do need a higher voltage than red but as you say it is not as high as 4 Volts. I too have seen lots of cheap devices where white LEDs are connected straight across a 3 Volt battery without any apparent component doing the current limiting so just relying on the batteries internal resistance.

Without knowing more about the OPs project its hard to speculate whether white LEDs would be suitable. If the supply is 3 Volts and has (relatively) unlimited current capability then the resistor value would be very critical especially if the supply was unregulated.

Ian P

If the torch has a reflector then a bulb is the way to go, as Ian said, LEDs only emit light in one direction making a reflector a waste of time as very little of the output hits it. I have tried many times to use reflectors with LEDs and never managed to improve beam width.

Cheers Derek.

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Harry,

If the existing set-up is just a bare bulb on the end of a flexi, then 'most any 5mm White LED would probably be OK; but if it has a fancy reflector, we may need to think a little harder.

Could you post a close-up photo of the business-end of the flexi torch ?

Thanks

MichaelG.

Edited By Michael Gilligan on 21/11/2014 22:24:12

Edited By Michael Gilligan on 21/11/2014 22:27:51

Hi Harry,
CPC list 2.5 volt LES bulbs but are showing them as out of stock at the moment. (No price given.) I have seen quite a few torches where the bulb is rated at a lower voltage than the battery so this might do if the come back in stock. Another possibility is the very small 2 pin bulbs used in the small Maglite torches. You may be able to solder one of these into an LES base or change the type of holder. I have also seen this type of bulb in some 2 x AA torches sold in the Pound shops.If you look on Ebay for "maglite bulbs" you will also find some LED conversions for torches that use the 2 pin bulbs. These drive the LED properly with a switch mode step up converter. Youmay be able to adapt one of these.

Les.

Not sure if this is helpful or not...

You can file off the surface of leds to diffuse the light if you want to use the reflector.. but that seems a bit counter productive. More sensible perhaps to use more that one led or use a surface mounted type which are less focucussed.

Also if after miniature bulbs then those sold for use in auriscopes and ophthalmascopes are tiny.. but you would need a different holder, Heine is one supplier.

pgk

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Maybe this is why.

MichaelG.

Hi Michael, if you click on Derek's link and then in the left hand column on componets you wil find electrical and electronics and then click on bulbs & LEDs you wil find **LINK**

Regards Nick.

Edited By Nicholas Farr on 22/11/2014 08:05:34

Thanks, Nick

But I was simply answering Bogstandard2

MichaelG.

Edited By Michael Gilligan on 22/11/2014 08:08:43