Project Help

[GQGeek81]

No clue which subforum this really belongs in but we'll start here.

I've been toying with the idea of making a "Random Screen" http://tinyurl.com/2u2e3h ever since I saw it in MAKE last year. I however want to make it big enough to use as a room divider (among other tweaks) and I want it to be electric.

The original is neat and all but would be a complete PITA to light and put out to the point that I expect I would only rarely bother to use it. On top of which it seems like it would be a serious fire hazard.

My thoughts are to use small incandecent bulbs that 'hopefully' will put out enough heat to make the top portion spin. For the construction I was thinking thin MDF spraypainted silver (maybe) to make it reflective and faced off with something like a sheet of rice paper or the like.

What I need are some suggestions on what bulb to use. It obviously needs to get reasonably warm but not to the point its going to burn/melt anything. Cheap would be the next requirement as I will need quite a few of them. Power consumption would be the final one although I imagine this might conflict with the first requirement.


Any thoughts?

 

[brickbat]

If the only tool you have is a hammer, you tend to approach every problem as if it were a nail. In light of that, I really like the candle-based approach, especially for a non-electronics type.

If I were constructing one of these, I'd probably use some form of electronic dimming control of the lamps, and forego the convection spinner. Maybe as simple as a collection of 555 timers… Others might hook a bunch of PWM drivers to a USB interface and develop a windows-based app to program them, or put the whole deal behind a WiFi node, and be able to remotely set up their patterns. Or use tri-color Lamina Ceramics LEDs and be able to program the colors and set it to music or ambient sounds and...… well, I digress…

One reference I saw says a candle flame puts out 100-300 BTU/hr. If true, that equates to about 30-100 watts of heat. (about 3400 btus in a kW-hr) Since incandescent lamps pretty much turn their entire electrical input to heat, (They are inefficient light sources, but efficient heat sources) start with a lamp in that range. Obviously, the lower the friction in the bearing, the better balanced you make it, and the less stray air currents around it the better, and maybe with this could you get by with less power in the lamps. Also, maybe you can 'funnel' the heat from the lower boxes in the grid to those above them to allow smaller lamps in the upper boxes. Or, hmmm…use a small fan to move the air, ducting it from one box to the next ?? Way more efficient than convection from electric lamps.

Really cool idea – thanks for posting…

 

[GQGeek81]

Doing it electronically is an interesting option. There are some projects on Instructables about making jars of fake fireflies. Changing the LED color (and output) would probably work nicely, although I kind of like the idea of making it semi mechanical.

I'll have to get some bulbs and cans and experiment.

 

[65535]

It wouldn't be hard if you changed the timing of the on off cycles at a different rate for each lamp, what would be really neat would be having it change frequency within a range and each box would have its own range or frequencies. PWM at ultra low frequencies, and capacitor dimming and ramping. I'm sure some EE could help you out.