Variable output levels

I'm sorry in advance if this has been discussed before.
Why doesn't anyone come up with a switch that would allow 'infinitely' variable brightness/output levels? It should solve the too-bright/short runtime, too-dim/long runtime dilemma.
I mean how difficult is it to design a switch similar to, dare I say it, vibrating women's toys? That way, nobody needs to carry a lot of flashlights (I say a lot, not one), or fiddle with confusing switch combinations (even double-clicks from what I've read somewhere - unbelievable).

Yes I once proposed modifying a vibrator. Especially those metal ones would be good for heat transfer. I don't know how waterproof the switch is, though, other than "it should be". I think it would be an interesting project.

The problem as I see it would be that most incandescent bulbs need to burn hot and when dimmed there life would be greatly reduced. They would also yellow the more they where dimmed LED's would be a better light source to do this to. /ubbthreads/images/graemlins/smile.gif

AilSnail, isn't there already a flashlight floating around on ebay (possibly from Hong Kong?) that looks like a vibrator?

McGizmo made a flashlight with an epoxy lens that looks remarkabley like a marital aid.

/ubbthreads/images/graemlins/ooo.gif

/ubbthreads/images/graemlins/grin.gif

Incandescent bulbs, none too efficient to begin with, drop precipitously in efficiency as the supply voltage and filament temperature drop below design targets. This is a bad thing in any setting, but when you're dealing with a severely constrained power supply (like a handful of AA cells) it's worse. Getting half the light from the bulb would require a lot more than half of full power, and cutting the power to the bulb by half would result in far less than half the light output. And whatever power regulator or resistor you used to dim the light would eat up some power too, so battery-life savings from a dimmed light may be negligible.

To get multiple output levels from an incandescent source, it may be a better idea to use multiple bulbs or multiple filaments of differing resistances (and thus different powers), as is commonly done in 3-way table lamps and automotive signals. And in the Surefire 10X, come to think of it.

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Lagged2Death said:
Incandescent bulbs, none too efficient to begin with, drop precipitously in efficiency as the supply voltage and filament temperature drop below design targets..t.

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So my X10 whole house system with variable dimming is costing me more than 100% brightness would. IOW, when the lights are dim I'm paying the power company more?

(sorry for slightly off subject question)

Brightnorm

Actually Rex, I am a big believer that lights with the feature you are asking about would be a giant leap forward in the world of flashlights. I'd really like to see some sort of a reostat (sp?) type of switch, with a click on, click off feature. I think a 5W LED would do the trick as well, and I agree with Lagged2Death that a incandescent would never fit this bill.

Hopefully Arc's new LS4 and LS5 will pave the way for more companies and modders to follow. Can't wait till they come out.

MSax

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brightnorm said:
So my X10 whole house system with variable dimming is costing me more than 100% brightness would. IOW, when the lights are dim I'm paying the power company more?


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No, I don't think so. Sorry if I'm not being clear.

When you dim an incandescent, you get a lot less light and use a little less power (and a lot more bulb life, too). A dimmer does reduce power consumption, but not as much as it reduces light output.

I don't have any exact figures to cite, but you may, just as an example, get 40% of the full-power light when using 70% of the full-power electricity. So dimming a light does reduce your bill, but it's not exactly a bargain, either. A lower-wattage bulb running at full voltage could produce the same amount of light for fewer watts, without the yellowing effect. (Which of course doesn't do the trick for you if you like the yellowing effect for residential lights - I think a lot of people do.)

It's no biggie, though. Lighting is usually a relatively small part of the residential electric bill (unless you've got a house full of those power-gobbling, fire-starting halogen torchieres), so dimming vs. not-dimming won't effect your bill much. And the ability to dim is undeniably handy, when you're plugged into an endless supply from the grid.

But I do suspect a flashlight user wouldn't be too pleased to find that putting up with a sickly yellow glow was only extending his battery life a tad. Better to go with a bulb designed for low output, which would stay whiter longer.

MSaxatilus, if memory serves, those old television sets used to have the volume controls that you'd also pull for on, push for off. It can't be much of a mod to turn that sort of thing into a clickie! /ubbthreads/images/graemlins/smile.gif

Pulse width modulation is attaining 98% efficiency in incandescent dimming circuits right now. Good info on PWM at Willie Hunt's site;
http://www.cs.indiana.edu/~willie/lvr.html
You can buy LED head lights that use PWM for dimming now also (I think). Also, a modder on this board is working on a PWM tail switch.

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Overamp said:
Pulse width modulation is attaining 98% efficiency in incandescent dimming circuits right now. Good info on PWM at Willie Hunt's site...


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It may be that some of the regulation circuits are that efficient, but the bulbs themselves (and thus the flashlight as a whole) never approach that sort of efficiency.

Willie Hunt's site actually has a nice table giving concrete numbers concerning the phenomenon of lowered efficiency at low voltages. His example uses a 4V, 2W bulb. At about half power (0.98W), you only get about 17% as much light as at full power, and at half voltage (2V), you only get about 8% as much light as at full power.

So at those low power levels, you're using the batteries up slower, but (at least at 2V) you're paying about five times as much for every one of the few photons you're getting. I guess even with flashlights, it pays to buy in bulk. /ubbthreads/images/graemlins/smile.gif

This is (and coming from Mr. Hunt, it's intended to be) a powerful argument in favor of using regulation in incandescent lights - but regulation to maintain consistently high output levels, not low. (LEDs don't have this dropping-efficiency problem, so you're not wasting battery capacity by allowing an LED flashlight to dim.) Strange then that so many LED lights are regulated and so few incandescents are.