The There Are No Stupid Questions Thread

If the light is designed a certain way, it’s rather easy: unscrew about a quarter-turn.

The light must use a tail-switch board that insulates the negative end from the battery cap (my Emisar D4 does this). So, the negative path is: Battery ()> spring -> trace near edge of board -> end of battery tube when it screws down fully and contacts the trace. Uh, probably a good example of a non-anodized light that does this is the titanium D4 series.

flightless22 was specifically asking about lights that don’t have anodized threads.

Right, which I was specifically addressing. If the light is designed properly, the current path doesn’t use the tailcap, and all you have to do is lift the battery tube off of the contact board that sits in the bottom of the tailcap. The D4Ti should be an example of this - but I do not own one, and therefore cannot test it. There’s some discussion here but I didn’t find anyone confirming it by testing.

Umm, no. I think it’s safe to say (only he can confirm) he was asking something along the lines of:

“I have a light that doesn’t have anodised threads. Can it be made to physically lock out?”.

Eg, my ’502s don’t have ano threads, and can’t easily be made to lock out.

Short answer is no.

Longer answer is yes, if it doesn’t have a spring on the driver side, but only a small bump/nipple, and can take flattops.

In that case, a thick enough O-ring can be dropped in to physically try to push the cell away from the driver. Only tightening it up would squish it tight enough to make contact. So it basically becomes a twisty with tailswitch.

Ok, so I have few stupid questions.

What do “slicing” and “dedoming” mean in relations to a LED and what effect do they have?

Dedoming is removing the entire dome off the led. You typically might soak it in a strong chemical or heat it up in order to carefully lift up and remove the dome. For LEDs where that won’t work, you can very carefully slice the top of the dome off.

In layman’s terms, the dome increases the apparent size of the LED die and you get extra brightness, but it also makes the hotspot a little larger reding throw distance. With the dome removed you get the effect of the actual die size, the brightness is a bit less and the hotspot becomes a little smaller which will increase throw distance.

Just adding on here, dedoming or slicing LEDs often also has a significant effect on the color temperature and/or tint. The expectation is that the color temperature can be reduced by as much as 500K and the tint can be brought from “green/yellow” to “pink/purple” side of the BBL (i.e., duv is reduced). For example, XP-G2 was dedomed primarily for throw purposes. The LH351D is currently frequently sliced for tint reasons just as much as throw reasons (it is both a very floody emitter, and frequently is found to have undesirable green tint, especially at low levels).

Does dedoming have any effect when emiter (say LH351D) is coupled with a TIR optic? Say I dedomed LH351D in my Skilhunt H04… what would happen?

Asking for a friend :smiley:

If you’re comparing the domed LED to the sliced/dedomed emitter in the same TIR, you would still get increased throw and decreased duv, as well as warmer tint. You would also get decreased lumen output.

TIRs are super useful for blending an emitter’s output (certain Cree emitters, like XP-G3, have an awful tint variation from hotspot to spill in a reflector, and a TIR evens that out quite a bit) or for getting certain specific beam shapes. On the whole, they’re not going to change an LED’s tint - this is best demonstrated by something that has consistent tint in a reflector already, and comparing it to a TIR. Luxeon V or XPL-Hi come to mind. What’s neat about a TIR, especially something like a 60 degree pebbled TIR, is you can throw in emitters that have much less desirable tint-rainbows in a reflector and have everything come out nice.

Can same be achived by swaping TIR with different degree one? For instance, I’d like more throw from my headlamp, instead od dedoming my emitter could I put a 20* TIR instead of 60*. Do they work like that?

Thank you for taking time to explain it in noob terms.

Yes, a narrower angle will give more throw.

Can a driver be checked for output voltage without a led hooked to it ?

It depends on the driver. For instance, a FET based driver has battery power going directly to the LED and then the negative side of the LED goes to the driver and it is what controls the current.

You should be able to hook up power to a boost driver and measure the voltage output although it may not be super accurate since there’s no load.

I don’t know a whole lot about Boost, Buck and regulated drivers so I can’t really say for sure.

So what specific driver are you referring to?

It is working now, MT07 Buffalo that fried a led a few weeks ago. I will get you a full update if I get time tonight, busy now. Thanks for helping again. :wink:

Cool. That light has one of those wierd regulated driver designs I’m not familiar with so I’d be no help. :stuck_out_tongue:

It is fixed, What did you mod today? .
I removed the burnt led and it was re-flowed OK. I had wanted to check the driver voltage before risking another led. So that not an option, we hooked it up and turned it on. It fired up with no problems, so the burnt led is still a mystery. Thanks again for your help Jason !!

"EDIT: No it does not have to be about flashlights at all"

Ok, here goes: Why is it that human beings are designed to feel comfortable in such a tiny temperature range? A 50 degree Fahrenheit temperature range ( 27.8 Centigrade degree range ) is so tiny in the physical world, yet 40 degrees F room air temperature feels so cold and 90 degrees F room air temperature feels so hot. Why can't I feel ok/fine with a much wider ambient room air temperature, even if the temperature is within 38 to 93 degrees F? Normal people complain if room air temperature is below 66 or above 78. I feel comfortable with room air temperature anywhere from 72 to 74. Why wasn't my mind and body designed to feel ok/fine with real world temperature range?

I would say your mind and body IS designed to feel ok/fine with real world temperature range. It seems to match pretty well with the temperatures of the planet. At least we are warm blooded and can survive extreme temp swings.

My theory: We feel uncomfortable/pain/anxiety to react on a given situation. Clearly, above a certain temperature our DNA denaturates, so that is a valid concern. Below a certain temperature we’re going into energy saving mode, unable to defend ourselfs against potential enemies. Takes too much time to warm up, or, in constant alert mode, consumes too much energy. So we seek company or a warm place when it’s cold. But our body needs to notify us about the necessities.

When we were formed, we had to make sure to survive and being able to hunt. And all we have is that tiny DNA fibre that has formed in the oceans and limit our abilities to adapt.

Here goes my “there are no stupid questions”, question:

If I wanted to use the convoy 4x18a for a host for the sbt90.2, is there anything that needs to be done to the driver? Does anyone know what type of driver is in the 4x18a? Ideallly, does a dd turbo work best for sbt90, to get mot out of led on turbo?