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making LED light units
blakep82 - 8/2/12 at 10:03 PM

kinda...

got some plates cut by Andy (top man! as always!) what i'm going to do, is mount some 12v leds in for rev gauge, fuel gauge, dash warning lights etc.

slightly worried about the metal legs on the LEDs, with resistors, and wired hanging on then, so thinking about encasing the lot in clear resin, making them like 1 light unit, rather than a ali plate with LEDs glued in.

what can i use to stop light transmitting through the plastic and out of the next LED along (like fibre optics do)
drop of black paint round the LED before the resin? black marker pen?

also, need to make a sort of mould round the back of the plate. how about some sort of plasticine or bluetak build up into a trough shape to hold the resin til it sets? would paint/pen/anything else react badly with it? any sort of resin dye type things perhaps to stop light?

[Edited on 8/2/12 by blakep82]


gavin174 - 8/2/12 at 10:13 PM

go to a city electrical factors....

and ask for magic gel..

its a dragons den product..

mix and poor

its basically a jelly that insulates.

used in the eletrical trade to make joints, adaptable boxes waterproof...

magic gell

[Edited on 8/2/12 by gavin174]


MakeEverything - 8/2/12 at 10:28 PM

quote:
Originally posted by gavin174
go to a city electrical factors....

and ask for magic gel..

its a dragons den product..

mix and poor

its basically a jelly that insulates.

used in the eletrical trade to make joints, adaptable boxes waterproof...

[Edited on 8/2/12 by gavin174]



I remember the good old days, melting candles to waterproof submersible boxes!!


blakep82 - 8/2/12 at 10:31 PM

hmm, does it stay as a jelly though? there won't be a box to fill, it really needs to hold itself together, ie solid.
I've got LED tail lights where the whole circuit board is in the plastic, and just the wires come out, so thinking the same thing is a good idea for this


mark chandler - 8/2/12 at 10:39 PM

You young boys !

You need to look in some old telephone exchanges, paper insulated copper cores in a lead sleeve, then twisted jointed and sealed in a lead jacket as the cables are pressured from the exchange to stop water ingress.

For myself I used a hot glue gun on my cbr900 clocks, held the wires a treat


blakep82 - 8/2/12 at 10:49 PM

enough talk of waterprrofing junction boxes thanks! there's no junction box!

hot glue gun is a good call. that was my first idea, but i remember hot glue being a bit bendy? i really need to hold these wires up to about 2.5cm or there abouts, where the LEDs legs join resistors


mark chandler - 8/2/12 at 10:57 PM

You could make a cardboard mould, line with cling film for a smooth finish then fill with fibreglass resin


blakep82 - 8/2/12 at 11:00 PM

quote:
Originally posted by mark chandler
You could make a cardboard mould, line with cling film for a smooth finish then fill with fibreglass resin



lol well that was kinda the original question, but with blutack! would that work to hold everything in place? not worried about it being smooth really, it'll sit in the dash board anyway


femster87 - 8/2/12 at 11:50 PM

As brought up yesterday, plasti dip?

http://www.plastidip.co.uk/eStore/index.cfm?Plastidip_Liquid_Electrical_Tape_-118ml&stage=3&colour=Black,Red,White&pid=PDL-0019


blakep82 - 9/2/12 at 12:35 AM

what will plasti dip do? i thought that was a kind of rubberised paint?


coyoteboy - 9/2/12 at 12:39 AM

Cardboard mould then pot in black potting compound, simples.


blakep82 - 9/2/12 at 01:46 AM

awesome! potting compound looks the stuff i'm after then thank you!
fits the bill all round i think. guess i'll have to get it from maplin. can't think of anywhere nearer


mad4x4 - 9/2/12 at 06:14 AM

potting compound

Different types soft/ hard isulative non/insulative etc

Available for CPC / Farnell / RS / possibly maplin / any good electrical wholesale

Could use heatshrink round the LED's to mask sidesm, bit thicker and a bit more permenant than marker pen


femster87 - 9/2/12 at 08:30 AM

quote:
Originally posted by blakep82
what will plasti dip do? i thought that was a kind of rubberised paint?


I think the insulation dip is a spin off of the paint technology


coyoteboy - 9/2/12 at 12:27 PM

Maplin do this one: http://www.maplin.co.uk/px804c-epoxy-resin-391533

But I'm fairly sure potting compound is just epoxy with dye added. Food dye? Never tried it, might leach out in rain I guess.


MikeRJ - 9/2/12 at 02:49 PM

If you are directing multiple emitters into a solid block of plastic you will get light transmission all over the place from internal reflection unless you add a opaque shield (i.e. tube) from the emitter to the surface of the plastic. If you look in commercial electronic goods that use a single plastic moulding to transmit light from multiple LED's you will see they remove as much of the plastic between the LED's as possible, but you still tend to get a lot of light leakage between them.