Adjustable Incan?

[ElectronGuru]

So I have a 200+ lumen 2C incan with a 1.5 hour total output light (half the time below 100).

Is there a way to add adjustability so as to turn it down and boost runtime? I'm interested in real-time options with an externally mounted dial/switch as well as changing something internal that can be changed back and forth to produce high or low when needed.

I'm okay sweating to make it, but either must be durable and easy to use.

Thanks.

 

[mdocod]

with incandescent lamps, under-driving reduces efficiency, so you tend to get less "light/hours" even though it may run slightly longer. Only way to have effective dimming on a incan is to have multiple bulbs.

 

[mudman cj]

AW's regulator will run bulbs at 100%, 60%, and 30% IIRC. I haven't seen runtimes for typical bulbs though, so I don't know just how much longer the lower power levels extend battery life.

 

[JasonC8301]

I don't really think adjustable incandescents are viable. I have not seen one yet designed to be power adjusted between different voltages/levels.

Incandescent bulbs are usually designed to be run at a very specific range or voltages. Anything more and poof, there goes the bulb. Anything less is a sickly yellow beam that will reduce the life of the bulb.

For now I am enjoying the two levels of light from my Surefire 10X.

 

[ElectronGuru]

AW's regulator will run bulbs at 100%, 60%, and 30% IIRC. I haven't seen runtimes for typical bulbs though, so I don't know just how much longer the lower power levels extend battery life.

Looks like even MORE than I was wanted:

http://www.candlepowerforums.com/vb/showthread.php?t=168596

Thanks for the info everyone!

 

[sysadmn]

with incandescent lamps, under-driving reduces efficiency, so you tend to get less "light/hours" even though it may run slightly longer. Only way to have effective dimming on a incan is to have multiple bulbs.

PWM works about as well on incans as on LEDS. You run the bulb at optimal current, but turn it on and off thousands of times a second. Willie Hunt is the first I heard about using it.
http://www.cs.indiana.edu/~willie/lvr.html

 

[DM51]

PWM will turn an incan on and off, but the short pulses won't give the filament time to heat up or cool down between pulses. With a LED, PWM gives you a square wave, but an incan can't react as fast, and the wave will be smoothed and flattened out.

The beam will therefore "average out" the power it is receiving, and will become more and more yellow as the overall power decreases.

 

[mdocod]

I agree with DM51 on this one, a PWM will not do any better than any other form of dimming as far as bulb efficiency and color temp goes, the only advantage of PWM is that the regulator itself would be very efficient.

 

[ElectronGuru]

What would be cool is some kind of dimmer built into the tail cap, such that fully tight = max and you just unscrew it to turn it down. Even so, I can see myself getting AWs module (and batteries) eventually, that switch is outstanding!

 

[sysadmn]

PWM will turn an incan on and off, but the short pulses won't give the filament time to heat up or cool down between pulses. With a LED, PWM gives you a square wave, but an incan can't react as fast, and the wave will be smoothed and flattened out.

The beam will therefore "average out" the power it is receiving, and will become more and more yellow as the overall power decreases.

Interesting - I did some research to prove you're wrong, and found you're right. There are ways to work around some of the problems, but they're new enough that the effect on lamp life and efficiency is still being modeled.

Current research is focusing on using higher-voltage sources with PWM to drive automotive lamps. Several of the papers I found (looks like they were funded byh OSRAM) discuss using 42v DC to drive 12v lamps; it's thought it will be cheaper than dc-dc conversion. Even those focus on one or two lighting levels, not many or infinitely many.

 

[DM51]

That research sounds very interesting, but my immediate thought is that 42v into a 12v lamp, even for a millisecond at a time, is going to stress it too much. Please keep us posted about this if you hear more!

 

[MikeSalt]

Dimming an incandescent will cost you colour-rendition and lumen efficiency.

You say you don't mind sweating to make it? In that case, I have an idea. I assume you are familiar with the Surefire A2 Aviator? Well, what I am suggesting is to have your flashlight with the primary (200 lumen) bulb mounted as usual for full-power use. You will need to drill out three radial holes in your reflector. In these positions, mount three lower-power incandescent bulbs / LEDs. Fashion a switch to control them independently, then you have a multi-level incandescent!

 

[paulr]

You can't really dim an incan without affecting its efficiency. There are multi-level incan lights, but they work by having more than one filament, for example car headlamps (separate filaments for high and low beams). The Surefire 10X Dominator is powerful 2-level incan flashlight: it has two separate lamps, a 60 lumen and a 500 lumen. You can turn on either one, or both simultaneously.

 

[ElectronGuru]

Fun idea, though the switching would de-simple the interface (a design requirement for this project).

Thanks!