The There Are No Stupid Questions Thread

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djozz
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WARvault wrote:
Will the BangGood A17DD driver cook the LED in my Ultrafire C8? I’m asking for a friend…

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.
djozz
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bansuri wrote:
Is there something like Moore’s law with LED emitters?
I’ve refreshed many old lights with newer emitters and the increased output is amazing.
Will I look back on today’s emitters 10 years from now and laugh at how weak they are or has this technology been nearly pushed to its limit?

Not asking for crystal ball answers, just wondering if anyone has deep knowledge of how far this can go.


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.

singularity35
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Will governments regulate lumen output in a few years?

Chuck Roxas

joechina
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AlexGT wrote:
What gives li_ion a 4.2v charge? Why is it not 6v or whatever random volt we need? Why 4.2v or 1.5 for alkaline and 1.2 for Nimh?

Here http://batteryuniversity.com/learn/article/when_was_the_battery_invented
below figure 3
It applies to every battery.
Instead of two metals LiIon uses Lithium (-3. something volts against carbon)

jch10400
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Zulumoose wrote:
klrman wrote:

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

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

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

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

wle
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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..

wle

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AlexGT wrote:
If you could fire a laser in one direction of the cosmos and it didn’t disperse or hit anything that would absorb it, given enough time. would you see it coming from the opposite direction from where you sent it?

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

djozz
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ryukin2000 wrote:
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.

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ryukin2000 wrote:
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 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.
ryukin2000
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djozz wrote:
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.

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.

Flashy Mike wrote:
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.

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

Thanks guys.

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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?

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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?

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ryukin2000 wrote:
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.

I have done this a few times.
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Can lithium ion batteries be stored together safely as long as only one positive and negative end are touching? ie: two 18350 batteries in a single 18650 case.

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bansuri wrote:
Is there something like Moore’s law with LED emitters?
I’ve refreshed many old lights with newer emitters and the increased output is amazing.
Will I look back on today’s emitters 10 years from now and laugh at how weak they are or has this technology been nearly pushed to its limit?

Not asking for crystal ball answers, just wondering if anyone has deep knowledge of how far this can go.

https://en.m.wikipedia.org/wiki/Haitz%27s_law

moderator007
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Snoballz wrote:
Can lithium ion batteries be stored together safely as long as only one positive and negative end are touching? ie: two 18350 batteries in a single 18650 case.

Yes!
bigm
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singularity35 wrote:
Will governments regulate lumen output in a few years?

They will if people give them a reason like they have with laser pointers. It is important to follow common sense and etiquette when using our high power lights. All it will take is a few idiots blinding traffic, messing with police and rescue, or children losing their vision from staring into extreme light sources to get the ball rolling on legislation.

djozz
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bigm wrote:
singularity35 wrote:
Will governments regulate lumen output in a few years?

They will if people give them a reason like they have with laser pointers. It is important to follow common sense and etiquette when using our high power lights. All it will take is a few idiots blinding traffic, messing with police and rescue, or children losing their vision from staring into extreme light sources to get the ball rolling on legislation.


I just checked the dutch regulation for bicycle lighting and was quite surprised that no output limit was set. I do think that it will be added at some point.
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Thanks for all the non-stupid answers guys. I have another non-stupid question. Can I “bulk out” a hollow pill with a slurry of copper wire bristles and solder blobs, heated with a butane torch? I dunno if I am explaining it well. My plan is to cut some strands of wire into little ~2mm bristles, cut ~500mm of solder into rice sized grains and cast the mixture into my hollow pill. Has anyone tried it? This is to increase thermal mass for the Ultrafire C8 mentioned earlier in the thread… Thanks again!

djozz
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WARvault wrote:
Thanks for all the non-stupid answers guys. I have another non-stupid question. Can I “bulk out” a hollow pill with a slurry of copper wire bristles and solder blobs, heated with a butane torch? I dunno if I am explaining it well. My plan is to cut some strands of wire into little ~2mm bristles, cut ~500mm of solder into rice sized grains and cast the mixture into my hollow pill. Has anyone tried it? This is to increase thermal mass for the Ultrafire C8 mentioned earlier in the thread… Thanks again!

I think you must first ask yourself if filling up a hollow pil is going to give you a measureable performance gain. Using a standard 1.6mm copper DTP board on top of a hollow pill, if the connection to the edge is well done, will give you pretty good performance already, perhaps over 4A you start noticing a gain of filling up the pill.
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some where i saw a blf host diy. I thought it was banggood but can’t seem to find it now it my also have been a sofrin host does anyone know what i’m referring too. thanks

Steven W Rhea

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What’s the trick to soldering emitter leads to the emitter board?

I did my first three driver swaps and soldered the leads to the original emitter boards (to aluminium, one copper) without a problem, but now that I’m trying to put a new emitter in my L2 I just can’t melt the solder on the pads.

I have a 30W temperature controlled soldering iron. Do I need more power?

djozz
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skinny_tie wrote:
What’s the trick to soldering emitter leads to the emitter board?

I did my first three driver swaps and soldered the leads to the original emitter boards (to aluminium, one copper) without a problem, but now that I’m trying to put a new emitter in my L2 I just can’t melt the solder on the pads.

I have a 30W temperature controlled soldering iron. Do I need more power?


It is about three things, more of each is better:
*power (but 30W with a quality tip is enough for most emitter board joints)
*contact surface (the pointy end of a small tip is not going to do it, a bit further down the tip where it widens is much better, or use a flat-end tip)
*a clean tip loaded with some fresh solder for a good thermal bridge (oxide layers are excellent thermal insulators)
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… and one more thing:
I don’t know if you are trying to solder to an already mounted MCPCB – if yes, it does what it is expected to do – leading the heat away. Lift the MCPCB a bit. If there are screws – loosen them before.

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Thanks djozz and Flashy Mike.

I think the tip might be the issue – it’s a small conical tip and there isn’t enough room to use the side, and it is looking a bit oxidised.

I’ll try some tip tinner and working with a blob of solder on the end. If I still can’t get it to work I might get a cheap 40W it on and flatten the tip.

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How are babies made?

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Can a HF 9-led 3-AAA giveaway light be modified in any useful way economically?

Great... Carnac the Magnificent tells me I just signed up for yet another expensive hobby.

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lightlight22 wrote:
singularity35 wrote:
Which end of the flashlight lights up? Silly

Both… hehe

I got one just like that!

I bought it at the Darth Mall.

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

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What is the impact of a reflector which is not 100% spotless?

To tweak the beam of my C8 i have sanded down the gasket until it was paper-thin, which improved the beam but it was still not a laser beam, it diverges.
So i filed down the reflector quite a bit, i dont have the guts to go any further at the moment.
Filing and sanding caused a dirty reflector. I have messed up 1 reflector earlier and now i know it is a p.i.t.a. to get it clean.

Got it quite clean with soap, running water and a hairdryer Wink but it still shows minor stains due to dried water, which annoys me, do i have to, other then cosmetics?

Edited by: sb56637

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