Hi, this is my first post, hope you can help. I'm an industrial design student, fairly inexperienced in electronics, though I have soldered circuits together before, and I know the very basics (V=IR, what a capacitor and resistor and PCB are).
I'm wanting to make a reading lamp, with the light source being a small array of LED's with output of about 400lumens in total, and area of about 35X25mm. It will be powered by mains power, via a plug-in transformer. DC or AC, I don't really know the pros and cons. The switch will be in the power lead initially, though I am interested in perhaps making a passive infra red switch, (waving hand in front of light for on or off) or capacitive switch using the metal housing.
The light doesn't need to be dimmable, and doesn't need the capacity to flash or anything like that.
I"m wondering where to start with all this. Can I buy an array of LED's off the shelf, with a choice of AD/DC, voltage, power, and just solder up 2 wires, or is it more complex?
Thanks in advance for your help,
Andrew

 

AC is used to transport electricity.
DC is used for everything else.

Just get a wall wart, a little black plastic box that plugs into wall outlet. AC goes in, DC comes out. Simple, effective, no headaches.

Figure out which LEDs you want to use to produce 400 lumens. Once you know the LED model, then the rest can be designed.

 

400 lumens is pretty bright. I would be tempted to just buy a cheap Chinese bulb from Ebay.

http://www.ebay.com/itm/GU10-4W-4-L...8851124?pt=US_Light_Bulbs&hash=item19e2c6a334

 

Some surface mounts are quite bright, like 225 L, 3.3W 21V @ 115 mA, $ .99 on special, or 174 L in warm white, 2.72 - 2.85V @ 700 mA, $ 1.69 from Electronic Goldmine. Would need heat sinks.

 

Can I buy an array of LED's off the shelf...

Yes, and I recommend that. If you choose something like this one, you'll just need conventional lamp parts.

I assume you want to build the lamp, not just have one? I mean, there are nice ones you can just go buy and I would recommend that if that's all you want.

 

Sorry I should have been more descriptive. I want to convert a vintage film camera into a reading lamp by mounting an array of LED's where the film usually sits. So the light source needs to be quite flat and small. I thought about buying a cheap flashlight/headlight, tearing it down and seeing if it fits, but also thought there may be a more elegant solution - an array of LED's on a small pcb. Would I have to make this myself, (drilling holes in a pcb and soldering each one - series, parallel? )- or is there something off the shelf I could use?

 

Sorry I should have been more descriptive. I want to convert a vintage film camera into a reading lamp by mounting an array of LED's where the film usually sits. So the light source needs to be quite flat and small. I thought about buying a cheap flashlight/headlight, tearing it down and seeing if it fits, but also thought there may be a more elegant solution - an array of LED's on a small pcb. Would I have to make this myself, (drilling holes in a pcb and soldering each one - series, parallel? )- or is there something off the shelf I could use?

Just buy perforated pcb: http://www.digikey.com/product-sear...totype-boards-perforated/2359508?k=breadboard

Choose the size. If you need really small, buy a slightly larger one and when it arrives carefully cut off the extra materials.