The There Are No Stupid Questions Thread

If it is a genuine cree, no problem

Is the DX80 in turbo mode strong enough to spot a hiding Sasquatch?

Is this a stupid question?

As long as you have most of the other prerequisites:-

A camera that cannot focus
Shaky hands
A lack of corroborating witnesses
Redneck ancestry

Title of this thread... "The There Are No Stupid Questions Thread"

......I think I have a lot of those prerequisites. Photos to soon follow of blurry images of something that really is just a blurry image and to others a sign of big foot.

If the led is soldered onto a alumnium non-DTP board (this is what the Ultrafire C8 likely came with), yes probably it will cook. If the led is soldered onto a copper DTP-board (such as a Sinkpad, Noctigon or KD-DTP board) and is clamped down with some hermal compound in between, it will be fine.

With led technology, there is a theoretical limit of about 300 lumen/W for white leds (a bit more for green leds). We are now at over 200 lumen/W so for led efficiency at least Moore’s law certainly does not apply. But we may be able to stuff more and more power in a little volume and make ever so brighter leds, but they require ever more powerful batteries (and regarding Moore’s law and batteries: regardless of the chemistry you can only stuff so much energy in a volume before you are litterally producing bombs) . And with laser pumped phosfor light sources that are just now on the market that power/volume is rising again.

Overall I see exciting improvements ahead but also too many theoretical limits to believe that Moore’s law will apply on leds.

Will governments regulate lumen output in a few years?

Here BU-101: When Was the Battery Invented? - Battery University
below figure 3
It applies to every battery.
Instead of two metals LiIon uses Lithium (–3. something volts against carbon)

Plus, most sightings occur in the presence of either Jack Daniels (Northern latitudes) or Jose Quervo (Southern latitudes).

Is there a limit to the efficiency of LEDs?

What limits efficiency?

(If they were 100% efficient, there would be no heat sinks or warm lights.)

Even if some of the ‘light’ had to be at invisible wavelengths, I just don’t want it to sit there and heat up the flashlight…


Nope, it will just go straight on into the forever growing ‘nothing’.

what is an alternative way to keep a 17mm driver in place? i have a cheap 18650 zoomable host and it keeps popping out. i have tried soldering it to the pill but no luck. it used to fit tight but not anymore.

If the pill is brass, you could try to solder it with lots of flux and a very hot solder iron, I have a 80W monster for that kind of work.

If the pill is aluminium, at two positions around the driver I solder a thin copper wire around the edge from ground ring to ground ring, if possible I try to start the wire inside a via. After soldering (I try to get the solder all around the edge) I file the edge to shape so that the driver is still just too large for the cavity in the pill, and the component-side-ground-ring filed back to almost flat. Then I solder all the ledwires and last the driver is pressed in the pill between a vice. The driver is then held in place by friction, and it has good electrical contact with ground.

If you don’t need an electrical connection between pill and driver (e. g. if the tube is pressing directly onto the driver when screwed in) you could also glue the driver to the pill with a small amount of Arctic Alumina or similar. Two tiny drops of glue at opposite positions is often sufficient.

The pill is aluminum and I couldn’t even get the solder to stick even with lots of flux. Even feels like a lower quality aluminum. I may try the wire filler as you suggested.

Electrical connection is required but glue might be my only option.

Thanks guys.

I have an 20700 protected cell from an Acebeam L30. It doesn’t fit in any of my chargers including the MC3000. Which charger can handle a cell this long?

Here is a question that I can’t find an answer to.
Immediately after a rechargeable Li-ion cell is manufactured, what is its voltage?
Is it zero?
Is it perhaps around 3.7v? If it is then charging it to 4.2V would be in a sense over volting it.
How could it be zero when first manufactured? If it is then they would have to have been charged to about 3.7 when shipped. If they are, then why is it that first initial 0V state not damaging to the cell?
I personally think they are manufactured at 3.7V and shipped. (no charging after manufacture)
Also, I have witnessed 10 year old NOS ( new old stock) cells resting those 10 years at 3.7V charging up and performing almost as good as new. Another question would be if a brand new cell was charged to 4.2V, then discharged to 3.7V and put aside for 10 years. Would it still charge up and perform as new , just as a NOS cell does?

I have done this a few times.