Want advice on mod

My wife has a little book reading light just like this one. (I didn't buy hers at Radio Shack, but it is just like it.) It runs on two AAA batteries and is quite usable. It's bright enough and it's light so it doesn't drag down the book. The only problem is that it doesn't have much runtime.

I'd like to make it run longer so am thinking about a mod like the PR Bulb Base LED Modification on Quickbeam's site.

This light uses a screw-in type bulb rather than a PR base, but the principle should be the same. I have several questions, though.

First, the light is not "pointed" down in the original. The direct light is reaching the page from the "side" of the bulb. Does it make sense to proceed anyway? I suppose it may be possible to mount the LED(s) in the base so they point to the side where the book would be, but that may or may not work in practice.

Second, if it does seem sensible, then what about a 2- or 3-LED arrangement? Would this still have a reasonable runtime advantage over the OEM incandescent? Should I wire the LEDs in series or parallel? Does running any of the LEDs off a pair of AAAs with no step up or regulation seem reasonable?

Third, if this does look to make sense, what about a source for LEDs? The whiteleds.net site that Quickbeam lists as a source seems to be defunct. What other site is known or suspected of being a good source. I see one member has turquiose LEDs for auction on eBay, but I think white or yellow might be preferable for a reading light. I found someone else who has yellow Agilent (Part number: HLMP1440) LEDs on eBay. Are these known to be good parts for this sort of thing. I noticed Peter Gransee says he is using Agilent LEDs in the yellow Arc AAAs, but would those be the same or different parts? I looked at Craig's site and could not find these LEDs, but I don't know if I was looking at the right page(s). (The "Agilent Barracuda &Prometheus LEDs" page goes to a "Luxeon Star / Barracuda / Prometheus" page that has nothing about this LED.

Thanks for your patience with a newbie.

Paul

Paul, the WhiteLEDs guy is finally back in business. his new web address is:
http://www.whitelightled.com/

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Silviron:
Paul, the WhiteLEDs guy is finally back in business. his new web address is:
http://www.whitelightled.com/<HR></BLOCKQUOTE>

Are these similar to the 5600mcd 5mm LEDs sold by others, like Hosfelt, for about $3.00. If so, this is an excellent price!

Wayne www.elektrolumens.com

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by prn:
My wife has a little book reading light just like this one. (I didn't buy hers at Radio Shack, but it is just like it.) It runs on two AAA batteries and is quite usable. It's bright enough and it's light so it doesn't drag down the book. The only problem is that it doesn't have much runtime.

I'd like to make it run longer so am thinking about a mod like the PR Bulb Base LED Modification on Quickbeam's site.

This light uses a screw-in type bulb rather than a PR base, but the principle should be the same. I have several questions, though.

First, the light is not "pointed" down in the original. The direct light is reaching the page from the "side" of the bulb. Does it make sense to proceed anyway? I suppose it may be possible to mount the LED(s) in the base so they point to the side where the book would be, but that may or may not work in practice.

Second, if it does seem sensible, then what about a 2- or 3-LED arrangement? Would this still have a reasonable runtime advantage over the OEM incandescent? Should I wire the LEDs in series or parallel? Does running any of the LEDs off a pair of AAAs with no step up or regulation seem reasonable?

Third, if this does look to make sense, what about a source for LEDs? The whiteleds.net site that Quickbeam lists as a source seems to be defunct. What other site is known or suspected of being a good source. I see one member has turquiose LEDs for auction on eBay, but I think white or yellow might be preferable for a reading light. I found someone else who has yellow Agilent (Part number: HLMP1440) LEDs on eBay. Are these known to be good parts for this sort of thing. I noticed Peter Gransee says he is using Agilent LEDs in the yellow Arc AAAs, but would those be the same or different parts? I looked at Craig's site and could not find these LEDs, but I don't know if I was looking at the right page(s). (The "Agilent Barracuda &Prometheus LEDs" page goes to a "Luxeon Star / Barracuda / Prometheus" page that has nothing about this LED.

Thanks for your patience with a newbie.

Paul<HR></BLOCKQUOTE>

I could not bring up the link on the light to see what it looks like.

Can you attach an external battery source, and use larger batteries, like 'C' cells or 'D' cells?

I once attaches a single Nichia white LED to a 4 AA battery pack, and resisted it down. The LED was on the end of a couple of long wires. This LED could be attached to reading glasses pointed down at the page. I made it for a friend so he could shine it down the barrel of a rifle for cleaning. I found the LED to be a very practical. One LED overdriven a little bit puts out enough light for reading, but for sure 3 would definately be enough. Lots of possibilities here.

Wayne

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Silviron:
Paul, the WhiteLEDs guy is finally back in business. his new web address is:
http://www.whitelightled.com/<HR></BLOCKQUOTE>


This link does not seem to work. Anyone else having this problem?

Never mind, it worked like 2 minutes later.

Paul -

First, don't try to run white LEDs with 3v (2-AAA batteries). The light output will be so dim it will be essentially useless. Some amber and red ones like those found in Photon lights will run very brightly with 3 volts, but white ones won't.

Second, if you cannot direct the LED's at the page directly, you will not be able to take advantage of most of the light they produce. You can sand them down gently to create a more diffusing effect, but again a lot of light is lost in the wrong direction unless the booklight has a directional cover/reflector (I assume it does - your link didn't work).

Third, go ahead and use 3 LEDs! Three amber ones are used in the CMG Bonfire light with 3 volts and they do produce a lot of light! You won't run down the batteries anywhere near as fast as you would with an incandescent bulb. Wire the LEDs in parallel with no resistance if you use high output amber LEDs.

Where do you find them? Someone else will have to answer that. I stocked up on whites from whiteleds.net when he was around. I usually don't do mods with other colored LEDs. Hosfelt is supposed to have decent LEDs, but I don't have any experience with them.

Have you looked at the www.ledcorp.com site?
Not only do they have PR base bulbs but they also have screw base bulbs. They are three cell though. Sino Union Tech Co. has a two cell PR base LED. See the LED Museum for a review of both.

Yes, and http://www.techass.com has the 2 cell pr bulb as well. It has a tiny step-up circuit to run the LED at full brightness on only 3v. All the other 2-cell white LED bulbs suffer from the same problem - very very dim output on 3v (as in useless output) unless you go with a Luxeon Star emitter.

yeah, i'd say one out of like 10 sites i go to ends up having to be reloaded. Maybe not that many, but it's always something i try.

- Pete