Hokay here's one for you "Techno Guru's" out there:

I have been given an array of UV L.E.D.'s, that has a simple circuit, no protection, drivers etc, just a bit of Varioboard with 26 Leds, wired to a +ve and a -ve terminal.

Now I'm fine on mechanical things, but Lectrickery is a closed book - (its all blue smoke AFAIK), do I switch the +ve side or the -ve side?

many thanks.

BTW: the array is going to be housed in a bodged Speliotechnics/Oldham housing, with only an on/off switch.

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I think it only matters if your circuit is grounded in which case you switch the non grounded side.

Convention is to switch the positive side.
What you do may be influenced by charging your lamp. Does it need to plug into a through the headset charger?

Nope charging is no issue atm, will be running dispoasbles, so the +ve sets teh switch many thanks!

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Right now for the clever bit form me some photos!

[photo]100690[/photo]

The headset is I think Spelio, the bottom switch fork I rebuilt moons ago, that nice SS fitting went in today, its 1/4" NPT, and is bomb proof!

[photo]100691[/photo]

The Array, courtesy of my mate Dunc, yellow is the negative.

[photo]100692[/photo]

Oldham bezel, two glasses, and a portbottle cork, to hold it all in place.

I'm guessing that the Green wire will connect to the RHS terminal and the yellow left to the LHS terminal. I have some sexy 2 core cable, and am going to maplins soon for the supply end!

Am I on the right track (haha) here folks?

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I may be talking out of my rear!
But I would check the glass for UV transmission. You don't want to loose a large part of your output. :smartass:

UMMM ok????

I have managed to reduce the glass by one layer by adding the grommet from a reflector, and reckon with a longer cork the emitters will sit snugly!

I'd not considered optics yet, as I stated I'm coming from basics, just what I've manged to cobble together, gotta learn to crawl first!.

My objectifies are thus:

1- make a bomb proof housing.

2- installing simple on off circuits, maybe multiple switching later!

3-supply of 'leccy - I'm off to maplins soon and intend getting 4x AA typo battery holder and project box, as I readily have a cable gland and cable, which will allow varying voltage.

(this unit is 3v. I suppose a range of 1.5 to 6v dc is possible, I kno nuffink about 'leccy other than it go POOF!! and let out teh bloo smoke and costs a lot of munney!)

4- see wha'appen, its not going to be a main light, more something to use for photogage/experimentation!

I have a reliable biffllight duo, this is a bit of a toy rheeellleyyyy!:lol:

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A few things.
Oldham headsets normally switch on the low side, the block at the bottom is usually called the "positive terminal block" which has an external stud which is to engage and contact the lower spring strip if that's a good description, on a charging station.
It wont matter on yours but you could have a problem if you ever want to charge it though the headset.

Secondly you don't say what type of array of 26 LEDs, series or parallel or a mix?
I mean if they are in series and each has say a forward voltage of 3V at the appropriate drive current, then multiply 26 X 3 and work out the number of AA batteries you will need.
:o

Or have I missed something somewhere.

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A bit more
Assuming they parallel, the AA battery holder is series (usually are, 1.5V only drives clocks) and the vF at a 30mA drive current is about 3V, then 4 AAs will give about 6V

Yes, they all go poof

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hehe Roy!

only the bezel and glass are oldham!, AFAIK the headset is Spelio.

[photo]100693[/photo]

this is wot the back look like, plenty poof, series?

Oh and I forgot to sa I saw it run on 2x AA duracell on the workbench!

Btw dribblin over the dragon......

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Going to need some sort of spacer to prevent led's pressing into back of glass, also some way of locking the array to stop it rotating as you screw up the bezel.

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Why??

I was intending to allow the Leds to press onto the glass, as I have ditched one layer of glass and found an o ring to "soak" against a cork plug - which could probs be maybe 1/8" longer to allow for compression to stop things moving once tight.

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Because as you tighten the bezedl the glass has a tendency to rotate with it, winding up your wiring until it snaps! Doesn't always happen and you may find the glass skates over the top of the LEDs.

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hehe Roy!

Oh and I forgot to sa I saw it run on 2x AA duracell on the workbench!

So they must be parallel. 2S X AA = 3V, likely Vf of the LEDs
4S X AA = 6V
Poof

A constructive suggestion would be to use a 2X AA holder not a 4

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Thanks for all the comments guys, I'm going to be building over the weekend as I've just got the last few bits 'n bobs I need. I'll try and get a whole photo record of the build for Y'all to smirk at!

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Good luck with it.

I think I have made my point about the voltage, so if you want a better burn time why not use 2 X 2AA holders wired together + to + and - to -, that is, in parallel. So you would get 3V at double the capacity of a single cell. So say 2600 mAh cells would give 5200 mAh or 5.2 ampere hours in easy speak.

So 30mA X 26 = 780 mA.
5200/780 = 6.6 hours runtime, enough for the average trip.

You may well find a plastic box in Maplins that will hold the two double cell holders, but you will have to allow for cable gland.

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Mocked up front end:

[photo]100694[/photo]

Thanks Roy, I'll bear in mind what you say when shopping!

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Well done Wormster :thumbsup:

I know nothing about lamp building, or LED arrays or "serial this" or "parallel that" ut this is one of the most entertaining threads I've read in weeks! Keep it up! :lol: :lol: :lol:

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Maplin do 3 cell packs, approx 4.5 volts, may give more light intensity, wire two packs in parallel for duration?; comments, Roy?

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NO

Wouldn't it be nice if politicians gave such explicit answers to questions!

The difference in voltage between the Vf at the recommended current of 30 mA and poop will be less than 1 volt!

If you knew the make of the LEDs you could probably get a data sheet from somewhere, but my hunch is that the Vf will actually be 3.5V, however your 4.5 will still be a poof.

Tell you what, hold everything until tomorrow and I will dig one out and put some accurate figures up. Doubt much difference between yours and mine.

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