PWM Lighting (with incandescent globes)

G'Day Guys,

I'm trying to figure out what I need for this project. We're creating an artwork that requires 12 'lanterns', this project will be an artwork that has close relations to colour and music. As different signals are sent through a MIDI interface, the lanterns will light up, one lantern for each note. I can do all the midi stuff through the computer and just send what lantern needs to be light up and at what intensity via processing on the computer and send it across the serial to the Arduino, that's no problem, what is, is the lighting.

Our test lantern has about 5 white LED's in it, the plan is to die the thin paper different colours for each of our lanterns, the problem is cost (and I'm pretty bad at electronics). White LED's cost about $1.10 each so putting 5 white LED's in each lantern, and having 12 lanterns... it adds up pretty quickly.

I don't know how bright they'd be in comparison, but 2.5V Krypton Torch Globe is only $1.75 each, and I might be able to get away with just one in each lantern??.

My power supply is currently a 5V 2A regulated supply and I'm not sure this would be enough, I also have no idea how I'd use this +5V supply to power a 2.5V lamp?? let alone PWM them (would I need a series of MOSFETs?)

Any help would be much appreciated. Thanks,

Scotty

If you'd like to stick with LEDs, try here: http://www.oatleyelectronics.com/ They had white LEDs at 10 for$A4. I bought some, they seem OK and bright.

2.5v Incandescent globes on 5v supply: You will need power transistors of some kind to drive them (too much current for the Arduino outputs). If you adjust your code so the PWM is between 0 and 50% (not over 50%) this should take care of the voltage difference.

If Oatley still have those LEDs, I'd go that way.

I missed the bit about colours. :-[ Do you know LEDs come in different colours? Red and yellow could be cheaper than white; green are often more expensive.

oh, don’t worry about the colours, that’ll be an illusion from dying the paper, I just want white inside the lanterns :slight_smile:

Thanks so much for that link, I think I might go down the path of a few of the 50 packs (I can always hook up a few more in each lantern if they’re not bright enough, hey)

These LEDs are probably a LOT brighter, a LOT cheaper (than the 0.5W LEDs that Oatley sells, anyway), and have a really wide angle dispersion pattern. Probably ideal for your project. Downside is about 2 weeks shipping from China.

http://cgi.ebay.com/50pc-0-5W-8mm-StrawHat-WHITE-LED-LAMP-WITH-110-000mcd_W0QQitemZ260263998070

@ macegr: Are we on the same page here? Your link took me to a $A35 item! The LEDs I was referring to are ordinary 5mm, rated about 15000- 20000 mcd. 5 of these for $A2 sounds like a far better deal to me, and should look nearly as bright.

Downside is about 2 weeks shipping from China.

If this seems long, you've obviously never ordered from Oatley! ;)

We're not on the same page; the auction is for a pack of 50 LEDs. And the 5mm LEDs would be far, far dimmer than these. 20,000mcd versus 110,000mcd.