I've just been messing around with the new 3D World "mounting jig"
(for want of a better description:) and I plugged in one of my old
transformers which had the same outlet plug. It converts our local
240v down to anywhere between 1.5 and 12 volts. I was happy to see it
fire up the LEDs on just 6 volts (very weakly), give reasonable
brightness on 9 volts and excellent brightness on 12 volts. I
couldn't find any output voltages on the Chinese transformer and I had
expected it to be the standard Chinese 220 volts. I was real happy to
find 12 volts enough to power them.

Given the near useless nature of the unit as a mounting jig, a battery
pack seems worth an experiment to see how much drain the 36 LEDs would
have. I'm sure a compact light source for the handheld viewers could
be a real possibility.

Has anyone else been experimenting with these LEDs?

regards

Harry Calderbank
hcalderbank@bigpond.com

If anyone is interested in the new LED backlighting used in the 3D
World mounting jig, it runs very nicely off a set of eight AA
rechargable batteries. I've had one turned on all day (over ten hours
straight) and it has showed no signs of flattening the batteries yet.

Love to hear if anyone else has attempted putting this into a viewer
yet.

regards,

Harry.

hcalderbank@bigpond.com

If anyone is interested in the new LED backlighting used in the 3D
World mounting jig, it runs very nicely off a set of eight AA
rechargable batteries. I've had one turned on all day (over ten hours
straight) and it has showed no signs of flattening the batteries yet.

Love to hear if anyone else has attempted putting this into a viewer
yet.

regards,

Harry.

hcalderbank@bigpond.com

--- In MF3D-group@yahoogroups.com, "hcalderbank"
wrote:

>
> If anyone is interested in the new LED backlighting used in the 3D
> World mounting jig, it runs very nicely off a set of eight AA
>
> ...Love to hear if anyone else has attempted putting this into a

viewer

> yet.

I recently held my Saturn viewer (with the light back removed) up to
a litle 4 tube daylight lamp and the effect was incredible on some
of my old Spuddy slides. Some of my dimmer Velvia landscapes really
glowed, with a very strong sensation of sunlight bouncing off the
the dappled trees for the first time.

My stereo bud (who is seriously considering a 3D World) just called
me out of nowhere to tell my about a 4 white-LED light bar he has
that he wants to try in his Saturn.

--- In MF3D-group@yahoogroups.com, "lattie_smart"
wrote:

>
> My stereo bud (who is seriously considering a 3D World) just called
> me out of nowhere to tell my about a 4 white-LED light bar he has
> that he wants to try in his Saturn.
>

The 3D World lED actually has 36 LEDs arranged in two square patterns
each the size of a mount aperture. They are very bright, although a
little cool in colour temperature.

regards,

Harry Calderbank
hcalderbank@bigpond.com

hcalderbank wrote:

> If anyone is interested in the new LED
> backlighting used in the 3D World mounting
> jig, it runs very nicely off a set of
> eight AA rechargable batteries. I've had
> one turned on all day (over ten hours
> straight) and it has showed no signs of
> flattening the batteries yet.

I've been wanting to get some measurements
off this. Your note was a good kick to get
me on the project again.

Here's what I've found for power consumption
on the panel from my jig:

Vdc ma ev(iso 100)
7.5 10 10
9 55 13
12 180 14

So at 7.5vdc, the panel pulls 10 milliamp
and puts enough light at the top surface
that my Weston meter indicates 10EV for
ISO 100.

My regulated power supply has only a few voltage
steps, so I can't exactly duplicate your battery
arrangement. If I chart the data, though, I
can make some inferences. Eight nimh batteries
(which each generate 1.2vdc or 9.6vdc total)
would see a draw of about 70ma.

The AA batteries in my hand are rated at
2100mah (milliamp hours). There are batteries
rated at higher, but since the manufactures are
always "optimistic" in their ratings, I'll
use 2100 mah 'cause it makes the math work well.

2100 mah batteries delivering 70ma to this panel
should last about 30 hours.
2100 milliampHours / 70milliamp = 30 hours
This isn't really the case because the voltage
of the batteries drops as they discharge. This
will cause the panel to grow dimmer and the current
draw to decrease. The math is more than simple
division. My guestimate is that you could get
20 hours on that set of batteries before needing
to recharge. It will mostly depend on how dim
you are willing to use the panel.

Compare this to what I've measured on my florescent
panels and published at
http://stereo.thurstons.us/light_source.htm
vdc ma
7.5 240
9 270
12 310

We see that the LED panel easily pulls half
the current of the compact florescent I've been
using. The question is, does it produce the
same amount of light at the same voltage as
the florescent? Unfortunately, I can't answer
that right now. More measurements are needed
and I'll need to find my Sekonic meter first.
I know it's around here somewhere.
(Time to start turning over the piles.)
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

--- In MF3D-group@yahoogroups.com, John Thurston
wrote:

>

My guestimate is that you could get

> 20 hours on that set of batteries before needing
> to recharge. It will mostly depend on how dim
> you are willing to use the panel.

Your figures pretty well match up with my results John. The
batteries started to dim a little around the 12-15 hour mark. I
don't think they were fully charged to start with but were close to
it.

Given the use of a momentary switch, I think there is the potential
for a useful light source that will give some good time between
charges. Now, if I can just get myself some patient building skills
and do a job like you did with the compact flouro, I'll be happy.

regards,

Harry.
hcalderbank@bigpond.com

hcalderbank wrote:

> Given the use of a momentary switch, I
> think there is the potential for a useful
> light source that will give some good
> time between charges.

Yes. The florescent panel I used is not well
suited to switching on and off. It takes
at least 30 seconds to get up to its full
brightness (and longer as the battery voltage
drops). This is impractical. LEDs however,
are full brightness on power-on so the switch
would be perfect.

The big difference I see is that the edge-lit
florescent panel can be placed very close to
the slide without making hot spots. This let
me place the whole lamp inside the curved
diffuser of the MFPV. My initial measurements
indicate that the LED panel has to be placed
at least an inch away from the the diffuser
panel to prevent hot-spots. This is too great
a distance to fit inside the existing diffuser :(

When I last investigated this, I was looking
seriously at edge-lighting a similar panel with
LEDs. The idea was that it wouldn't be any
thicker than my existing panel, would be more
power efficient, and could be switched. I
haven't gotten back to this yet.

--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

Firstly, thank you for such an interesting discussion. Secondly, does
anyone know if the color temperature changes when the voltage drops?
This has been a curse in past lighting options.

Sam

--- In MF3D-group@yahoogroups.com, "Sam Smith" wrote:

>
> Firstly, thank you for such an interesting discussion. Secondly, does
> anyone know if the color temperature changes when the voltage drops?
> This has been a curse in past lighting options.
>
> Sam
>

So far, with the naked eye, color temperature looks to stay the same.
There is certainly no yellowing as with halogen. It just slowly fades
to a less bright white.

regards

Harry
hcalderbank@bigpond.com

---

Say hello to the next generation of Search. Live Search � try it now.

Patrick,

I love the cereal tub LED viewer! I've always liked the simple
approach of using and adapting whatever comes to hand. Good stuff!
Thanks for the photos. I'll look forward to the deluxe battery
powered model.

regards,

Harry.
hcalderbank@bigpond.com

Very cute Patrick.

Has anyone figured a similarly easy way to focus this viewer? Old
folks like me, whose eye's won't focus close anymore, can't use the
thing without reading glasses, and such glasses lead to vignetting, etc.

I suppose one way would be to bandsaw the thing in half and set the
focus back to 4 feet or so and put black duct tape around it. Kinda
ugly...

John