Fibre optic cable

Anyone know where I can buy something like this - apart from poxy EBAY? Still can't get signed in, keeps asking for the answer to a security question which I know is correct.

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want to get the light from a colour changing LED into my water feature.

Reply to
The Medway Handyman
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A google on "fibre optic lamp supplies" brings up this as the first hit:

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prices though, but there are others there.

Gordon

Reply to
Gordon Henderson

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>>> I want to get the light from a colour changing LED into my water >> feature.

Thanks, but I was kinda hoping to find a high street supplier. I have Googled but only found people selling reels of the stuff.

Reply to
The Medway Handyman

The Medway Handyman coughed up some electrons that declared:

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You're going to need some lenses to collimate your led into a beam to insert into the cable.

As your LED is inheriently extra low voltage, couldn't you waterproof it (eg potting epoxy from Farnell or RS inside a bit of plastic tube with the end of the LED sticking out of the end) and put directly in the pond feature? Assuming a SELV supply of course...

Cheers

Tim

Reply to
Tim S

Is the plastic (rather than glass) fibre optic intended for singlemode rather than multimode use then?

Reply to
Andy Burns

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>>> I want to get the light from a colour changing LED into my water >> feature.

Picky of water feature here

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I'm after doing is poking fibre optic between the gap in the two rocks, then up the hole so it illuminates the stream of water emerging.

I have a broken solar powered LED light I can use the LED & photocell from, but the cable isn't long enough & I don't do fiddly wiring/soldering.

Reply to
The Medway Handyman

What length do you require?

Don't Argos sell a fibreoptic lamp - it has about 10" of fibreoptic bunch - about a tenner, IWHT

Reply to
geoff

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Ebay is the right place to buy these off beat items. Just get over your phobia! open another account. How difficult is that?

Bob

Reply to
Bob Minchin

I doubt it... I don't recall ever seeing graded index plastic.

Reply to
John Rumm

It'll probably have a very wie acceptance angle then, so most LEDs would be directional enough to just aim into the fibre?

Reply to
Andy Burns

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>>> I want to get the light from a colour changing LED into my water >> feature.

Bloody near impossible Bob. I spent an hour trying this morning. Keeps saying I'm already registered even though I try to create an account using different details. Been right through the help menu, waiting for them to get back to me now.

Kin useless!

Reply to
The Medway Handyman

Indeed, the default construction of many a Christmas decoration!

Reply to
John Rumm

Andy Burns coughed up some electrons that declared:

Doesn't matter - sticking an LED with a 10,20 or 60 degree spread on the end of a FO cable is going to involve most of the light missing the cable completely.

OK - "beam" might have been a bad word, but you are going to want to focus the light onto the end somehow.

Cheers

Tim

Reply to
Tim S

Just wondering why Tim suggested a collimating lens then?

Reply to
Andy Burns

Andy Burns coughed up some electrons that declared:

This RBG led:

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I have, and is BTW quite good on colour mixing and very bright, has a

100 degree half-power angle.

The narrowest angle LEDs I've across have been in the 10 degree area IIRC, so you might get a partial result butting the cable up to the face but even then you'd waste a lot of light. I reckon the cable mentioned is about 2mm or so diameter which isn't that big.

Even if the cable has a good acceptance angle, that doesn't do you much good if most of the light flies straight past it. LED is almost a point source and an unlensed FO cable is almost a point sink. Sticking both in the end of a small internally silvered tube or possibly a perspex rod (internal reflection) would maybe be one way to attack the problem, or a lens.

Cheers

Tim

Reply to
Tim S

The Medway Handyman coughed up some electrons that declared:

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>>>>> I want to get the light from a colour changing LED into my water >>> feature.

I see your plan. I really think you'll have a hard time getting enough light through the fibre from an led to achieve the effect you want. The ends of the fibre will sparkle nicely at night, but I don't see much illumination potential, without injecting a seriously bright light into the end (eg halogen bulb).

You might get a better result making a light guide yourself, from a 0.5m bit of perspex rod. Heat it with a hot air gun and gently bend it into a shape (shallow bends) that fits between the rocks pointing upwards into the water. Have the other end appear behind the rocks and grind the end concave. Glue led into concave end with a bit of clear glue - that should capture a reasonable amount of the light output.

This is same technique used in some computers (well 1U servers) to take the HDD and LAN lights from a board mounted led to the front panel.

Go on - it's not that hard. You could even use a choccy block in a little waterproof box (besa box with a couple of flex glands, all available in B&Q. Set the led connections in a bit of car repair resin from halfords - it's mostly clear if it's thin.

Cheers

Tim

Reply to
Tim S

The internal reflection will catch more than you might think, looks like plastic fibre optic has a refractive index of just 1.5 and a numerical aperture of 0.5, so the acceptance angle = arcsin(1/3) or a 40 degree cone.

Reply to
Andy Burns

Andy Burns coughed up some electrons that declared:

Because christmas decorations just need to sparkle the end of the fibre (bugger all light needed). For TMH's application, I really just don't believe this will get anywhere near enough light in to illuminate anything externally (he want's to light the water up if I read it correctly). I might be wrong, but my gut feeling says "no".

See other post re point source and pount sink :)

Reply to
Tim S

Andy Burns coughed up some electrons that declared:

But Andy that assumes that the light is coming towards the fibre as a 40 degree *converging* cone.

With an LED, it will be approaching the fibre as a 10s of degree

*diverging* cone.

Eaggerated drawing:

/ / / LED S * FC \ \ \

The light's got to hit the * before you can even think about acceptance angles. If it flies past, missing * it's just not getting into the cable.

A practical test would be to put a little 2mm black dot of sticky tape on the end of the led in question and see how much bright light can be seen getting past it.

As I said - I don't doubt it will sparkle the fibres, but I don't think you'll actually get much useful illuminace from it.

Always suck it and see, but it would be a shame to spoil to effect for want of a cheap maginifying glass lens or a thickish bit of perspex rod, both of which may allow much more efficient coupling.

Cheers

Tim

Reply to
Tim S

In message , The Medway Handyman writes

Far too bloody complex all this fibre optic stuff.

Get some translucent, flexible tubing (aquarium type of thing) wide enough to accommodate the LED width, run a pair of wires through it, put a little heat shrink tubing over each wire.

Solder the LED to the end of the wires, jam the nozzle of a tube of silicone into the tubing at the LED end (might be an idea to see if you can get fish safe stuff if you have a pond with them in), fill the tube as far back as you can. Back fill from the other end if you feel it necessary.

Pull the wires back until the LED sits snugly inside the tube, bedded in the silicone.

Wait for silicone to cure.

Feed into fountain and power up with suitably safe PSU (batteries even).

Rinse and repeat until required effect is achieved.

Reply to
Clint Sharp

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