A question for the modders, incandescent regulation.

Most of us are dismayed at the alledged MSRP of the Surefire A2, the first regulated incancescent light to hit the market. Can a mod be made to regulate an exisitant incandescent light? One that comes to mind is the PT Surge as it already has good quality light output but is designed to run on sucky alkalines which produce a steadily dimming beam. I don't think any of us would want a "regulated" minimag!

Might consider looking into Willie Hunt's LVR

http://www.cs.indiana.edu/~willie/lvr.html

Might take awhile to get (custom made) but very cool...

John

The problem with trying to regulate an
incan is that by cutting back the juice
to a point that will provide longer run
time, you will get a light that is too dim
and shifted to the yellow. At this point it
has lost it's throw, which is what an incan
is good at doing. Just look at the
difference in the output of a 2 cell light
that has run the cells down to only 1.3
volts. When leds can maintain whiteness
down to very low voltages, I don't think
regulation is worth it in an incan light.
An incan light is good for high output
shorter runtimes only.

-Rebus

Willie Hunt is working at surefire

Rebus,

I believe the idea is to have a constant voltage throughout the life of the battery (as much as possible). This will reduce run time but allow the Incan to run at optimal voltage as long as possible. A stay bright and crash proposition. One nice thing about the A2 is after the battteries are no longer able to fire the Incan, the LED's keep burning.

- Don

Originally posted by Rebus:
The problem with trying to regulate an
incan is that by cutting back the juice
to a point that will provide longer run
time, you will get a light that is too dim
and shifted to the yellow.

Click to expand...

<font size="2" face="Verdana, Arial">If you look at the way that regulation is used for incandescent lights, you will see that this precise issue is addressed.

Rather than taking a voltage which will properly operate a lamp, and then cutting it down, the regulators are all intended to maintain a proper high voltage going to the lamp. If you follow the link to the LVR site, you will see that the recommended use requires that you have a battery voltage which is greater than the desired bulb operating voltage (the LVR is only a down converter). Some other regulators are boost converters which will take a lower voltage and step it up to a proper operating voltage for the lamp, but IMHO the LVR approach makes the most sense.

-Jon

A regulated incandescent may also have a longer [EDIT: corrected from "battery life"] bulb life. When you first turn on an incandescent bulb, there is a surge of current because the filament is cold and has low resistence. It quickly heats up (otherwise it wouldn't glow) which increases the resistence and the current drops to a steady state. This initial surge of current is usually what pops a bulb (ever noticed lights usually pop right when you turn them on?) In theory a regulator should help this problem a lot (at least if it's a current regulator) and should extend the average bulb life. I'm not sure if there is another factor I'm missing which would negate this benefit.

- Russ

Jonathan posted:
----------------------------------------------
Rather than taking a voltage which will properly operate a lamp, and then cutting it down, the regulators are all intended to maintain a proper high voltage going to the lamp. If you follow the link to the LVR site, you will see that the recommended use requires that you have a battery voltage which is greater than the desired bulb...
------------------------------------------------

That makes a lot of sense. I could not get the LVR
link to work before I posted the above. I hope they can get this to work.

-Rebus

Rebus,

I tested the link I posted above from this thread just now at 10:25pm EDST and it worked just fine. Willie's LVR's incorporte a "soft start" feature which should substantially increase bulb life by dimming up the lamp slowly thus reducing filament stress during startup. It's explained in detail on his website. The LVR's are also programmed to dim the lamp ever so slightly at about 1 Hz when the batteries are depleted to a designated level above the programmed output voltage. This serves as a low battery warning, so there is time to prepare before the battery is depleted. Some versions are available which also incorporate a low voltage cutoff to prevent damage to rechargeables. His regulators are also claimed to be 99 to 99.8% efficient.

One big advantage I can see here is that one could select a suitable lamp that offers a good lumens per watt ratio when overdriven, and although this usually greatly shortens lamp life, the soft start feature and precisely controlled lamp voltage allows one to push the lamp a little closer to the edge without detrement. For example, the Carley #1057 is rated for 6V/2A/12W/19CP/2900K/200Hours. If run at 7.2V/2.2A/15.9W you get 36 CP light output (454 lumens), higher color temperature (whiter), and still get 20 hours or better of lamp life. Lumens per watt also jumps to somewhere around 28! I think this is a fantastic regulator, and I hope to get mine soon.

Later - John