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Date: 04 Aug 2006 21:07:55
From: Dennis Woos
Subject: Modifying Rayovac 3-In-1 Headlamp
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Based on favorable reviews both here (s.a.a) and on CloudyNights.com, I
bought a couple of thse headlamps from Amazon.com (2 for $20). I like them,
but as already reported the red 2-led mode is way too bright for most
astronomy uses. Accordingly, I replaced the single white led with a red led
with a diffuse red lens. This gives a red light which is much, much dimmer
than the red 2-led mode. Replacing the led was trivial - disassemble the
headlamp by removing 3 screws and unsolder the white led and solder in the
red one. I like this solution, as it allows me to select whichever of the
two led brightnesses is most appropriate, as well as the krypton white
light. I am also going to find some kind of convenient cover for the
krypton white light, as I don't want to turn that on by mistake.
Dennis
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Date: 05 Aug 2006 14:18:13
From: Phil Wheeler
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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Dennis Woos wrote:
> Based on favorable reviews both here (s.a.a) and on CloudyNights.com, I
> bought a couple of thse headlamps from Amazon.com (2 for $20). I like them,
> but as already reported the red 2-led mode is way too bright for most
> astronomy uses. Accordingly, I replaced the single white led with a red led
> with a diffuse red lens. This gives a red light which is much, much dimmer
> than the red 2-led mode. Replacing the led was trivial - disassemble the
> headlamp by removing 3 screws and unsolder the white led and solder in the
> red one. I like this solution, as it allows me to select whichever of the
> two led brightnesses is most appropriate, as well as the krypton white
> light. I am also going to find some kind of convenient cover for the
> krypton white light, as I don't want to turn that on by mistake.
>
I have three of those headlamps. Where did you obtain the red LED with
diffuse lens? Do you have a part/SKU number?
Phil
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Date: 05 Aug 2006 11:59:41
From: Dennis Woos
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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> I have three of those headlamps. Where did you obtain the red LED with
> diffuse lens? Do you have a part/SKU number?
My sons mess around with electronics/robotics, and I used the first one I
pulled out of a drawer labelled "LEDS" (they are both away at camps). I
take it that the lens is the epoxy case housing the LED, and the two red
LEDs in the headlamp have a "waterclear" lens, i.e. even though they are red
LEDs they don't look red. The one I used to replace the center white LED
has a red lens, i.e. it looks red, and the lens is slightly cloudy which I
think provides the diffusion. However, now that I come to think of it, the
green LED I used for our Foucault tester was not diffuse, and I used
sandpaper to scuff up the lens and make it diffuse.
I don't think the LED is anything special. I would open up a headlamp and
remove the board with the LEDs on it, take it to RadioShack, and buy some
red LEDs that are the same physical size as the LEDs on the board.
Sometimes they sell a grab bag, which I think is what my sons have. After
unsoldering the center white LED you can easily test red LEDs without first
soldering them in by inserting them in the holes and using something
conductive (like small screwdriver blades) to short them to the pads.
The other way to deal with the over-brightness of the two red LEDs that come
in the headlamp is to dim them. I tried RubyLith, but you would need may
layers to make a significant difference. Another thing I considered was
raising the resistance of the resistors in series with the red LEDs.
However, the resistors on the board are surface mount, and are very small.
However, if you are adventurous you could try unsoldering one and replacing
it with a small (surface mount) variable resistor. This would let you dial
in the brightness, though I think you would have to set it before
reassembling the headlamp and leave it there. One reason I did not pursue
this further was that I don't really like the red light coming out of the
two red LEDs - it seems more orange than red. I did a web search, and it
seems that the wavelength coming out of red LEDs is all over the place, and
it is not uncommon for there to be a bit of green in the light. I like the
red light I get from the red LED with the red lens much more.
Finally, I still might paint one of the outer two red LEDs black, so as to
cut the light. The outer two are really bright, and maybe with only one the
headlamp would be more useful in that mode. My sons return from their
respective camps soon - maybe I should let them try the variable resistor
route? My younger son recently built a 1/2 watt tube guitar amp from a kit
(Gilmore Jr.), and he did a fantastic job. He also bought a 12" guitar
speaker (Weber), and I helped him build the cabinet. What a fantastic
sounding rig.
Dennis
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Date: 05 Aug 2006 16:48:49
From: Phil Wheeler
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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Dennis Woos wrote:
>> I have three of those headlamps. Where did you obtain the red LED with
>> diffuse lens? Do you have a part/SKU number?
>
> My sons mess around with electronics/robotics, and I used the first one I
> pulled out of a drawer labelled "LEDS" (they are both away at camps). I
> take it that the lens is the epoxy case housing the LED, and the two red
> LEDs in the headlamp have a "waterclear" lens, i.e. even though they are red
> LEDs they don't look red. The one I used to replace the center white LED
> has a red lens, i.e. it looks red, and the lens is slightly cloudy which I
> think provides the diffusion. However, now that I come to think of it, the
> green LED I used for our Foucault tester was not diffuse, and I used
> sandpaper to scuff up the lens and make it diffuse.
>
> I don't think the LED is anything special. I would open up a headlamp and
> remove the board with the LEDs on it, take it to RadioShack, and buy some
> red LEDs that are the same physical size as the LEDs on the board.
> Sometimes they sell a grab bag, which I think is what my sons have. After
> unsoldering the center white LED you can easily test red LEDs without first
> soldering them in by inserting them in the holes and using something
> conductive (like small screwdriver blades) to short them to the pads.
>
Thanks, Dennis. I have Radio Shacks and a more complete store (Signal
Electronics) nearby: RS is getting more and more difficult as they
change inventory, discontinue catalogs and the like (less parts, more
cell phones, TVs, portable DVD players, etc.)
I also have parts catalogs I can order from (I'm a ham and build my own
tranceivers these days .. to me, the best part of the hobby).
Phil
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Date: 05 Aug 2006 12:16:48
From: canopus56
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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"Dennis Woos" <dpwoos@gmavt.net > wrote in message
news:12d9g3jo32rpg4b@corp.supernews.com...
>The other way to deal with the over-brightness of the two red LEDs that
>come in the headlamp is to dim them. I tried RubyLith, but you would need
>may layers to make a significant difference.
One or two layers of Roscolux 120 will make it sufficiently dim for chart
reading and finding and picking up dropped objects. Twor or three will more
than dim it enough for the most dark-adapted seeing. For those of us who
are not ATM or electronic's inclined, no electrical hardware modifications
are needed. - Canopus56
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Date: 05 Aug 2006 14:45:00
From: Dennis Woos
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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> One or two layers of Roscolux 120 will make it sufficiently dim for chart
> reading and finding and picking up dropped objects. Twor or three will
> more than dim it enough for the most dark-adapted seeing. For those of us
> who are not ATM or electronic's inclined, no electrical hardware
> modifications are needed. - Canopus56
Maybe this is better stuff than what I have. Would you be willing to mail
me a couple of square inches to try? Thanks.
Dennis
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Date: 05 Aug 2006 01:05:52
From: canopus56
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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"Dennis Woos" <dpwoos@gmavt.net > wrote in message
news:12d7rrgs117015c@corp.supernews.com...
>I am also going to find some kind of convenient cover for the krypton white
>light, as I don't want to turn that on by mistake.
A Roscolux No. 120 gel sheet. Converts any white light source (flashlights,
computer screens, headlamps, car headlights) to astro-friendly redlight.
They come in 24 inch by 18 inch sheets (enough for lifetime) and are
available at local theatrical supply stores for $6-$9. I have converted a
number of headlights and flashlights using this material. Use two layers to
cut-down very bright LEDs. - Canopus56
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Date: 05 Aug 2006 14:26:25
From: Chris L Peterson
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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On Sat, 5 Aug 2006 01:05:52 -0600, "canopus56"
<canopus56@NOyahooSPAM.com > wrote:
>A Roscolux No. 120 gel sheet. Converts any white light source (flashlights,
>computer screens, headlamps, car headlights) to astro-friendly redlight.
What's the point? The resulting light will not be red enough, nor dim
enough to preserve your night vision. And you'll just be throwing away
battery power. To be truly astro friendly you still need to back up your
red filter with 10 or 15 layers of dark neutral material. Much better to
use red LEDs, and make the modification electronically.
The point here was that the white light remains useful, you just want to
avoid turning it on accidentally. Adding a second switch, or a
mechanical modification to the existing switch is the way to go.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 05 Aug 2006 19:36:56
From: canopus56
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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Dennis Woos wrote:
> Maybe this is better stuff than what I have. Would you be willing to mail
> me a couple of square inches to try? Thanks.
Not a problem. Email me an address off-group to canopus56@yahoo.com .
But a theatrical supply store may be quicker. They usually give away
Roscolux swatchbooks - a small 1 1/2 inch by 4 inch booklet that
contains sample sheets of all Roscolux gel sheets. - Canopus56
http://www.rosco.com/us/filters/roscolux.asp
Chris is right that the best solution is a variable light source since
the intensity of the light is the real enemy - less so than wavelength.
The variable source is there to allow you to make the light as dim as
possible to preserve scotopic dark-adapted vision.
The main value of the Roscolux gels over other materials is that they
are known material. You can get their transmission curves from the web
site above. The transmission curves are also printed in the Roscolux
swatchbook.
What I personally do to clip red (or white) LED light in astro
flashlights, that have lots of green and yellow wavelengths in them
(based on a thread discussion in this newsgroup with Chris a couple of
years ago) is to use a Roscolux 120 red and 83 blue. This leaves only
the clipped pure red light. The transmission factors of the two red
and blue sheets are something like less than 4%, so I use a variable
LED astro flashlight turned up quite high. By the time the light
passes the filters it is dim but can be adjusted using the control to
max for chart reading or down low for ultra-dark adapted observing.
Additionally, I have a couple of cheap white-light fixed-brightness
flashlights covered with the gel sheets for astronomy. One is a
headlamp that I also use for night nature hikes. These are not suitable
for dark-adapted observing, but are useful for finding and picking up
dropped and lost articles and for ground checks before leaving a star
party.
- Canopus56
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Date: 05 Aug 2006 22:57:14
From: Dennis Woos
Subject: Re: Modifying Rayovac 3-In-1 Headlamp
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> Not a problem. Email me an address off-group to canopus56@yahoo.com .
> But a theatrical supply store may be quicker. They usually give away
> Roscolux swatchbooks - a small 1 1/2 inch by 4 inch booklet that
> contains sample sheets of all Roscolux gel sheets. - Canopus56
I will check for a source in my area. Thanks for the info, and I will be in
touch if I am unsuccessful.
Dennis
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