Are your Luxeon's regulated or not??? Magic Thumb Test!

Want to know if your Luxeon based flashlights are regulated on not?

I figured out a simple 5 second test. No need to bust open your flashlight.
So far it quickly identified 18 of my Luxeon lights. Six were regulated and 12 were not.

Test is to be conducted in a dim or dark room.

Simply unscrew the tail cap. Push your thumb or finger where the tail cap spring was. Make sure to touch both the battery negative and the threads with the same finger. Your finger is acting as a resistor. If your light has a switch then turn it on.


1. If you can see your luxeon glow "very dimly" it's resistor or direct drive.

2. If you see no light at all it's regulated.

End of test!

PS: Let me know if you find a regulated light that glows with the magic thumb test. I have yet to find one.

Gasp!

It's magic!

Very clever!:laughing:

I tried it with 4 lights from AXShop.

9 LED 3AAA - worked
28 LED 3AAA - worked
1W fake Luxeon 3AAA - didn't work
3W fake Luxeon 2AA - didn't work

Regulated usually means that the output drops off slower than the input voltage. I think your test just detects whether there is an electronic circuit between the battery and LED, not whether it regulates or not.

Greg

I tried it with an Inova X5, and found that, since the positive contact is in the tail of the light, one has only to hold the flashlight in one's hand and touch the thumb to the battery contact to get it to light, albeit dimly. Shocking!

greg_in_canada said:

Regulated usually means that the output drops off slower than the input voltage. I think your test just detects whether there is an electronic circuit between the battery and LED, not whether it regulates or not.

Greg

Click to expand...

When I say regulated I mean current regulated, voltage regulated, booster circuits, down converters etc,..
So far none of them glow at all. It seems the thumb current is just so low that these circuits can't function.
All of my resistor and direct drive lights do glow using the magic thumb trick.

Ikonomi said:

I tried it with an Inova X5, and found that, since the positive contact is in the tail of the light, one has only to hold the flashlight in one's hand and touch the thumb to the battery contact to get it to light, albeit dimly. Shocking!

Click to expand...

Not only that, but you can touch your thumb to the batteries with one hand, and hold the light in the other hand! That must mean that current is flowing up one hand, through my chest (and heart), back down the other arm, and into the LEDs. Insanity!

I wonder if I can get it to glow brighter if I use my tongue?

Holy cow this works! I just tried it on my 3C NiMH DD royal blue mag. I guess your skin can conduct enough electricity for the led to light up.

This is only possible with LED, you'd never notice a incandecnet getting power!! neato!


EDIT: it also stays glowing after you take your finger off of it. Now THAT is really weird!! I guess the current left in the wiring/luxeon is capacitive enough to keep it lit!!! WOW!!

Isn't the human body like 90% water or something like that?

Might go some of the distance to explain that one... :shrug:

Water is a diaelectric. Meaning 100% pure water won't conduct. Get a tiny bit of impurities in it, and then it conducts!! The salts on your fingers probably help conduct too.


EDIT: it appears the luxeons stays lit not from capacitance, but if you have a finger on the battery, and your other hand on the knurling of the maglite. Yes it's conducting through the anodized area of the knurling!!

You probably shouldn't try this kind of stuff if you have a pace-maker!

SuperNinja said:

I wonder if I can get it to glow brighter if I use my tongue?

Click to expand...

I just tried it, and, yes, it is brighter.

Ikonomi said:

I just tried it, and, yes, it is brighter.

Click to expand...

Wow, you sure go to great lengths proving this theory. :bow:

I wonder how many micro amps the led is getting?

I have always wanted to hook up a mag mod led flashlight to where it was light all the time with heavy resistance, so it glowed at night. When you hit the switch it of course bypassed it. Perhaps even do that with a 555 timer in there for a flash of say 2ma power? That wouldn't use much battery life and would be a great locator beacon!!

SuperNinja said:

I tried it with 4 lights from AXShop.

9 LED 3AAA - worked
28 LED 3AAA - worked
1W fake Luxeon 3AAA - didn't work
3W fake Luxeon 2AA - didn't work

Click to expand...

My axshop 3AAA glowed ever so slightly with my thumb in the back. This was with half drained 700mAh NiMH's too

-patchy

ApacheXMD said:

My axshop 3AAA glowed ever so slightly with my thumb in the back. This was with half drained 700mAh NiMH's too

-patchy

Click to expand...

You can wet your thumb to get it to glow brighter.

I just did this with my Dorcy 3D Super 1W, and I found out 2 things.

#1. I did not have to touch the spring at all. I just had to use my finger to hold the batterys in. I tried touching the spring as well, but that didnt change anything.

#2. The more fingers on the battery, the better it glowed.

A high value resistor will also do the trick, around 68k ohms

Hmmm.... I just tried that on my Dorcy Metal Gear (which I'm pretty sure is NOT regulated) and couldn't get any glow. Maybe I'm just not conductive enough.

Will conduct more testing....

Edit to add:

Okay, a penny from the battery contacts to the thread lights it up full power, so I know I'm touching the right spot.

A dry thumb gives no glow at all. A wet thumb gives a modest glow. This is with fairly fresh Energizer Lithium primary cells.

Regulated or not?