crude homebuilt

mikep

Enlightened
Joined
Sep 22, 2000
Messages
305
Location
IL
Well, it's my first attempt: 4AAA 'battery holder box' from radio shack, which has a built in on-off switch+ 4 white leds. I toyed around with adding a resistor, but I hated to lose brightness. I crammed a wad of copper wire under the negative LED leads to heat sink, now the leads don't get hot. www.mindspring.com/~krispykreme/open.JPG www.mindspring.com/~krispykreme/closed.JPG
the on-off switch is sort of hard to see in the picture.
 
kewl
what is the RS part# of that box

---------------
 
Rats! I threw away the packaging for the battery holder. It's the AAA version of part #27-409 (which is 4-AA). Next time I go by RS I will find the number.
 
well i'll find it
it looks like a nice little box
and the project you made with it looks good

perfect place for me to toss some of my loose leds that i got to many of

the reason i am so interested is for weeks now i have had 3 AA rechargables just waiting for a place, but your brilliant idea of using the 4th hole for the stuff just worked out the last detail that was sticking in my mind.
what to do with the 4th battery slot
blush.gif
ohhhh
 
Mike,

Nice project!

What kind of current is going thru the LEDs?
You might be safe with the AAAs since they can't provide a whole lot of power.
wink.gif


How 'bout a pic with the cover on and lit up?
grin.gif
 
well that was EASY, thanks MIKE
i just finished mine in 45min
after 45 min in rs :)
i put in 4 turquoise 10*
and 4 red-orange 8*
makes for a weird but bright light
the color of the both of them isnt bad when combined
one is blue green the other is yellow red
both bright types
so i can actually see all colors with it mostly
as you would suspect there is a big red-orange spot in the center and a green spot on the outside, somehow they manage to end up all in the same place like instead of spread

i poured epoxy in the battery hole after i checked the wiring, solidifying the whole thing. (plug the end hole)

the box is not a perfect thing, it wouldnt survive getting rolled over by a wheelchair :) the switch is built in
and the springs could potentially let the batteries slop around a bit when impacted

the wiring for me was 3 nimi 1600ma on the cyan leds
and
when i couldnt find a resister i resigned and put the orange on 2 of the 3 batteries
when its ON the voltage is about 3.6 and 2.4 as one would expect
the amps is uhhhh
.79 or 2hours run time on the one i made

it also allowed me to test a theory
that cyan (which is a very bright led)
and red-orange (which is also very bright)
would give capacity for a pretty wide spectrum and some parts of it the color of incadescent light
 
This might be of use...
I used to make lights out of those Radio Shack boxes. They make them with covers and without covers. I quit because the switches failed. It was a shame as they made really compact boxes.

Here is the last one I made. To get around the bad switch...I put a mercury switch in it.

What you see is 2 batteries, a step up circuit ( SatCure ) and the glass capsule for the mercury switch.

I only use the "box switch" when I want to travel etc. To turn off, I just turn it upside down.
RS1.JPG


RS3.JPG
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Video Guy:
it also allowed me to test a theory
that cyan (which is a very bright led)
and red-orange (which is also very bright)
would give capacity for a pretty wide
<HR></BLOCKQUOTE>

Actually, one company is making a "white" LED using cyan and amber together in the same case. Apparently some of these curious things are winding up in the rear view mirrors of some Cadillacs, as map lights.

The CRI of such a device would be quite low, but very usable in any case.
 
thats it , i am changing my signature
the dang thing burnt out in the same 45min it took to build it
and now its epoxied in

the cyan ones did a little flash dance then bowed out exit stage left

geez this isnt fun anymore, no wonder everyone gets so technical on the forum
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Video Guy:

and now its epoxied in

<HR></BLOCKQUOTE>

-----------------------
Take a pair of needle nose pliers, twist gently and slowly and it will free up. I have taken many out this way.
 
-----------------------
Take a pair of needle nose pliers, twist gently and slowly and it will free up. I have taken many out this way.

---------------------------
ken did i happen to mention that being real smart i had all of the leads left on and imbedded interleaved into the epoxy,(this was going to cool them), that it was automotive epoxy , and it was a POUR of about 1lb of the stuff
tongue.gif

it filled the whole compartment and leaked into the side hole
your method worked, but nothing survived :)
ill get another case tomallee and see if i can do it right this time, i swear the whites dont die that quickly
and i thought the heat syncing would have it covered
frown.gif
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Go, Go Gadget Flashlight:
...What kind of current is going thru the LEDs?
You might be safe with the AAAs since they can't provide a whole lot of power.
wink.gif

How 'bout a pic with the cover on and lit up?
grin.gif
<HR></BLOCKQUOTE>

Well, I tried to measure the current with my el cheapo meter that only goes up to 250mA- blew it's fuse. So either it's over 80mA per LED, or I don't know how to use the meter.
tongue.gif


Before I crammed the copper wire in there as a heat sink, the negative leads got pretty hot to the touch.

The previous pics were direct scans of the box, since I don't have a digital camera.

It's been a good project to practice soldering, etc. I have found the handiest thing about the light is that it's very comfortable to hold in my mouth while navigating a dark house to fetch juice, children's Motrin, and a security blanket for a feverish 3 yr old.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by mikep:
... either it's over 80mA per LED, or I don't know how to use the meter...<HR></BLOCKQUOTE>

If you can measure the "in-line" current for each LED, you'll get a better idea. You might find something like the ambers are pulling 60 mA and the cyans are pulling 100 mA. Well... it COULD happen. The key thing is, if you do it that way, you stand a better chance of getting the meter to read it.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>I have found the handiest thing about the light is that it's very comfortable to hold in my mouth while navigating a dark house to fetch juice, children's Motrin, and a security blanket for a feverish 3 yr old.<HR></BLOCKQUOTE>

In other words, a "Bite - Light"! Well, not quite... if you had a switch you could control by applying a little jaw pressure... but anyway, that's my fav size, because I'm usually wandering around w/ my hands full of stuff... kind of hard to fill my arms w/ stuff and hold a LW4000 in my teeth.
grin.gif
 
Okay, how do I measure the individual current draws? I was putting the meter probes on the common positive and negative leads of the LEDS, and the meter pegged. (By the way- my light is just 4 white leds, it was Video Guy who used the other colors)
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by mikep:
Okay, how do I measure the individual current draws? I was putting the meter probes on the common positive and negative leads of the LEDS, and the meter pegged. (By the way- my light is just 4 white leds, it was Video Guy who used the other colors)<HR></BLOCKQUOTE>

To measure current, you have to "break" the circuit. The light should come on as you make contact with the meter probes. If it was on before you touched it, you were measuring current straight from the batteries in a dead-short.
shocked.gif
That's probably what blew the fuse.
wink.gif


Take one of the batteries out and use the meter as the jumper wires to put it back in the circuit. This would be total current.
To measure just one LED, take one LED lead off of the common wire. With power on, probe the common wire and the LED lead you unhooked. 3 of the 4 LEDs should be lit now. As you do, the 4th LED will light up and the meter will show you the current thru that LED only. Multiply by 4 and you have the total.
smile.gif


Next trip to RS, get a couple spare fuses. It happens to everyone at some time.
wink.gif
 
Cool, I'll try that out. I had just been poking them probey things on any exposed metal in that box- at least I had the meter set to measure current. Too bad I didn't take an EE lab class in school.
 
Guys...

Measuring current through an individual LED is not easy to do accurately. The rotten thing is that your measuring technique will tend to way UNDERestimate the current through your LED.

The meter you use to measure current does so by measuring the voltage across a small resistor in the meter. When you place the meter in series with an LED you are placing a resistor in series with the LED. Now if the resistance of the meter is very small it will not affect the reading too much if there is already a resistor in series with the LED of a much higher value. If the LED had no resistor in series with it, then you may be getting a pretty bad reading (far too low). If your meter has a range capable of 10 amps or more then the resistance is likely to be in the ballpark of milli-ohms. If your meters range is 100mA or so the resistance could be several ohms. You can measure the resistance of your meter set to a given ampere range with another (good quality) meter. Pass something near the range's maximum current through the meter and measure the voltage across the ammeter. So if you meter says 100mA (0.1 amps) and has 0.5 volts across it then your ammeter has a resistance of 5 ohms for that range (volts/amps=resistance).

A slightly better way to measure the current through a LED is to measure the voltage across it as accurately as you can. Then take it out of the circuit, and connect it to two meters. One to measure voltage across it and one to measure current through it. Increase the voltage to the LED till it matches what you had in circuit and look at the current on the other meter. This will be pretty accurate if the temp of the LED is close for the first and second measurements.

Direct current measurements by placing a meter in series with a LED are only accurate if the series resistance of your meter is at least an order of magnitude LESS than the resistance of the whole circuit. Like if you have a LED with a 100 ohm resistor in series with it and insert a meter with a series resistance of 5 ohms - then you'll be off by about 5% (on the low side).
 

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