Light Box

[Hughesie]

Hey

im looking to make a box that contains four halogen downlights with coloured glass over them

and i wondering what i would need to make the box

i want to be able to control each light via a switch (on, off) but it would be good if i could dim them also

all i have currently is one downlight and no power supply

any idea's?

[Chris15]

One question to start with, what voltage downlights are they. Are they 12, 24 or 240, or something else? That will seriously influence any recommendations, and also what wattage are they? If they are 12 volters and I interpret the "have no power supply to mean you have no transformer, then you are goinog to be looking at a substantial transformer to run 4 50 watt globes - at least 200VA, though you could do a transformer per downlight.

If you go for individual transformers, then dependant on whether you have a magnetic transformer or whether you have a switchmode power supply (electronic "transformer"), you should be able to dim them, though the transformers normally are marked and marketed as dimmable if they are. Do not attempt dimming an electronic "transformer" not marked as dimmable. From memory, a magnetic transformer will want a leading edge dimmer and an electronic "tranformer" will want a trailing edge dimmer, though you would want to confirm that before you tried.

As far as the box goes, halogen globes generate heat, and lots of it, so you will need either good cross flow ventilation, both for the globes and the transformers etc, or a forced ventilation system, read a fan or two. As far as the coloured glass over the top goes, my recommendation would be to instead go to Jaycar or DSE, Bunnings might even have them, and get the globes that have a coloured glass cover already attached. They come in Red, Yellow, Green and Blue. If those places are unsuccessful or you want some more ideas on where to get them, let us know.

The choice of construction material could be timber, or steel, or aluminium, or whatever you wanted, just remember the need for ventilation and that you'll need to cut 50mm+ holes in it to fit the downlights - not terribly fun in steel.

Hope some of that made sense, let us know if it didn't or more details are neeeded.

[Hughesie]

yeah i know where to get the glass (jaycar) the globes are 12v 50w ( i say globes but we have just renovated and had a spare one left over) so i can buy others

the transformers will be a problem i am only a student who would dearly love to avoid 240 wiring if i can

the ventilalation will be done

two fans on each side of the box

[jonhirsh]

Could you use A lamps to save your self allot of trouble.

JH

[ship]

What’s the intended use? Are you hanging the box and intending to control it remotely or just creating some form of strip light with the operation of the box mounted to the box? What’s the dimensions on the box and lamp spacing you were thinking?

Added to what Chris says, for halogen lamps - dependant upon wattage and cooling area inside the box in cubic area, you will need ventilation for the box and possibly fans. Air in and air out. From both sides of the box on a fan is fine as long as the center allows the air out.

Sorry, the info provided is not much to go with. Get help at school or with an electrician in doing this project.

[Chris15]

I just remembered what could be a get out of jail free card on the transfomers. Low voltage garden lighting is all the rage these days, and luckily for us, it uses 12 volt globes etc. If you use a garden ighting transformers (or more likely transfromers for 4 50 watters), then the 240 wiring is all done for you. My Jaycar catalogue tells me that a 105 watt indoor (ie. not weather resistant in any way) 12 volt transformer can be had for $39.95. (Though that might have changed by now - check their website & hunt around for them.)

I wouldn't think that two fans per side would be needed, perhaps ship could check this theory, but if you had single fan each side, set such that one blew in and the other out, the depending on the box volume etc, you should be OK. You could probably use 12 volt computer fans and run them off the transfomer - I would suggest that whilst for load balancing you should stick one on each transformer, it is probably better to put them bpoth on the same one so they operate as a pair. They'll only draw a couple of watts each, but it will depend on the actual fans you get as to whether you need to (and can safely) slightly overload the transformer or not. Now I've just remembered that you'll need a bridge rectifier or the like here so the fans get the DC they need rather than AC. A slight bit of filtration wouldn't go astray here either. Happy to give (and work out) the required details if need be.

I agree with Ship, given that you have said you'd like to stay away from 240 wiring, if the above solution doesn't work, find your nearest sparky to ask.

With a pair of transformers, you could then put a switch in series with each lamp and that would give you the basic level of control you wanted. If you wanted remote control, use relays on them and the equivalent of analog lighting control - 1 control wire per lamp, I'll give you more detail on this if you want it. I THINK that it is possible to use 240 dimmers on low voltage AC (which is what you get out of those trasfomers), but given I am perceiving , and I am sorry if I have gotten this wrong, that you aren't terribly confident at the moment, and so I recommend that you just stay with a switch in the 12 volt supply to each lamp - use a minimum 5 amp rated switch at at least 12 v - So a 5 amp 125 volt switch will handle it no problems. Doing it this way will allow you to add in dimmers or the like at a later date when you are more confident to do so.

[ship]

I would use both blowing the same direction so as to force air in or out from the middle of the fixture. Best forcing it in from the middle of the fixture. This given it’s necessary. CFM rates mean cubic feet per minute. The more the CFM rating of the fan, potentially the less need to do more than one other than a more balanced cooling of all lamps. A 6-cell cyc light for instance will often be 6,000 Watts of light. Naturally it’s going to be hottest in the center given not only the individual lamps but the lamp next to it adding to the heat in that cell. For that reason one would tend to want the coolest air to be coming in from the center. If end mounted fans, they would tend to want to suck in doing this.

I wouldn’t think two fans would be needed either but it’s an option. Still not visioning this light fixture given the amount of info given so I’m speaking in generalities.

[Chris15]

I see what you mean ship. I assume that you need to ensure air can get in at the middle - vents if need be? Hughesie, did you have thoughts on what you wanted this box to look like? I think that will quite affect the advice we give.

[Pie4Weebl]

Noobish question but if a fan really necessary? Outside or arc lamps in spot lights and movers I have never seen a fixture that is anything but convection cooled. From what it sounds like he is looking for a make your own 4 cell cyc light fixture with multiple colors.

[Van]

If I understand the original concept, you want 3 halogen down lights in a box on three seperate circuits ? do a Goggloe search for "Puck Light" they come in a wide variety of wattages. low voltage and standard. they get hot but they do not require fans. they can be recessed surface mounted, or whatever. They are dimmable, and can be colored with glass roundels availible for MR16 style track lights. I have an under counter lamp that has three built into it with an extra outlet. Don't know the brand but I can look for it. Why re-invent the wheel ?