Experience using Willie Hunt's LVRs?

[John N]

Experience using Willie Hunt\'s LVRs?

I was wondering if anyone has used Willie's voltage regulators? I've impulse purchased one of his LVR3C (5.5V) units and was just curious what people have done with them and what they think.

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

[stupid question follows]
Also, I see that output current is 2 Amps. Does that mean this can handle about an 11 watt bulb?

Thanks,

-john

 

[Illuminated]

Re: Experience using Willie Hunt\'s LVRs?

John,

Willie advises users of the LVR3C (which has only the small SMD FET) to limit their application to 2 amps max to allow enough of a safe margin for the startup current of the lamp, which could be rather "huge - even for a "small" lamp" to quote Willie himself.

When I asked what the maximum current it could actually handle would be, he said it was difficult to determine because it depends on many factors, including how quickly the lamp filament heats up and how long the current inrush lasts, etc. Because of this, he likes to steer users to stay well below the 2 amp level for LVR3C applications.

Have you received yours yet? I've been waiting for a very long time for my 3.8Volt LVR3C.

I plan to run the Carley #816 3.7V/.8A Halogen from (4) AA 1800mAh NiMH's for 82 lumens constant output with about 2.8 hours of runtime before low battery warning kicks in.

I think his designs are phenominal, and at 99% or greater efficiency, I believe that the added cost of regulation is worth the initial cost. (I just wish we could get constant-current step-down regulators for LED's which were THAT efficient.)

The regulation feature steals virtually no power from the source, and the dim-up feature should greatly reduce filament stress during startup, thus greatly increasing lamp life.

I personally won't be using the selectable reduced power level feature, as this is no substitute for a smaller lamp if less light is needed, and efficiency goes in the toilet.

This would, however, be a fantastic feature for an LED current regulator, as LED's I believe they are just as efficient when under-driven, if not more so.

IMHO, the ideal application for Willie's regulator circuits would be to somewhat over-drive an already efficient lamp to further increase efficiency and yield excellent color temperature of the light output, and yet still preserve 75% or so of the lamp's original designed service life.

In general, you'd aim for the best balance between efficiency/lumen level, and lamp life. This PWM regulator should let you operate a lamp much "closer to the edge" than you could without one.

I would venture a guess that not everyone fully understands the potential benefits of incandescent regulation, especially those who use lithiums with their flat discharge curve.

Maybe not AS much benefit for lithium use, but certainly for other battery types, especially rechargeables.

I will say that while I don't know much yet about the Surefire A2, I will be looking closely at it when it becomes available.

Good Luck!

John

 

[John N]

Re: Experience using Willie Hunt\'s LVRs?

Hi John,

I'm probably looking at driving a SF P60, hopefully in a Maglite "D" series light if I can fit it all in. I was thinking about the P60 because it has the built in reflector and I don't care much for the Mag reflector.

I'm tempted to try a P61, but it looks like it's 2.2A which might be too much.

Mostly I'm playing, I'm sorta using this as a learning experience, trying to work my way up to running a much bigger lamp from a "D" cell Mag using the LVR 3I or 3G. The cost of the 3C was attractive enough that it seemed like a good place to start.

I just placed the order so I haven't gotten it yet. I did order the "standard" config w/o no special options so that might speed things up a bit.

Thanks,

-john

 

[Illuminated]

Re: Experience using Willie Hunt\'s LVRs?

John,

Unfortunately (for me) I'm not well versed in the SF arena, so I'm not aware of their lamp specs. You could try asking Willie via email - he's been good at answering questions and offering good advice regarding specific applications for his product.

I, like you, would like to build a super light with high output, but it would probably have to be a larger light to house the LVR3I to handle higher current demands.

Interested as I am to start out with something to play with, I've decided to use the ultra small LVR3C and put it in one of two lights I have.

I have a Craftsman 4AA Tool Light with a faceted reflector that has a great, broad beam, and seems fairly rugged and waterproof (at least dunk-proof). I also have the Rayovac 4AA with the smooth reflector that has a very nice tight beam for throw (with a little help from WriteRight PDA film), and it's also dunk-proof. These lights were very inexpensive.

Both of these lights are similar in design and construction, and in fact, the bezel and lampholders are even interchangeable. With their somewhat larger heads, I think there's enough room to mount the LVR3C on the base of the lampholder.

I believe I could even switch them around and use the regulator in the broad beam reflector or the narrow one, depending on need.

My original interest in regulation is for use with bicycle lights I have that use MR11C lamps, and run on NiMH 6-volt battery packs. My autos have constant output headlights, and so should my bike. The low battery warning flashing would also be useful, since I wouldn't want to have to keep an eye on some indicator light on the battery or somewhere else, I'd just instantly know.

Seems to me that the standard 5.5V LVR3C is probably intended for use with the HPR50 PR-based lamp. It's rated for 5.2V/.85A/85 lumens/25 hours life. Re-rated for 5.5V/.877A/103.4 lumens, and the theorhetical lamp life drops to about 13 hours, though because of the soft-start feature, I'd bet that it'd actually be better than that.

The HPR50 is a popular lamp that is readily available for less than $5, and is used frequently by cavers and cyclists in various lights. There are others that would also be good for use with the LVR3C, you just have to decide where you want to go with your ideas.

Personally, I'd start with your battery requirements, and then find out what your lamp options are for the light that you have in mind.

Since you mentioned the *ag*ite D-cell, there are some tricks you can do to improve the lamp/reflector performance, and they are covered elsewhere in some recent threads. I have recently discovered a cheap way to texturize a *ag reflector (thanks to Lambda), and I am very pleased with the improvement. I'm also awaiting custom-potted PR-based lamps from Carley (shipping tomorrow). They have some excellent lamps to choose from for many different applications.

Also, you are not limited to just C or D-cells in the D-cell *ag*ite. Others have posted details for putting multiples of 123's in the the 2C versions, so you could possibly do a mod based on those ideas. I think 6 AA's has also been done.

The thing to keep in mind with the LVR3C is that the battery voltage needs to be higher than the 5.5V output to the lamp. This would be a good one for [edited - 5 cells, not 6] 6 NiCad or NiMH cells because you would be getting the low battery warning flash well before your cells were almost completely gone, so you'd get reasonable operating time before the LVR3C drops into extended dim run mode.

Willie advised me to try and stay at or below one watt-per-cell with AA NiMH's because he has tested them extensively, and their performance drops off quite a bit beyond that. He even suggests that 1200mAh NiCad's might actually provide longer run times than the 1600 or 1800 mAh NiMH's at higher discharge rates.

There should be enough room in the D-cell *ag*ite for the appropriate battery combo and regulator.

Good luck, and let us know how things work out...

John