"reverse" fired flashlights

[Bushman5]

one of my favorite lights is my Pelican Saberlight 2020 RECOIL LED. It is a single led reverse firing back into the reflector. I use for wilderness travel, SAR, boating etc, as it lasts a long time on a set of batts and is quite bright in the woods etc.

the "reverse' firing setup got me thinking though........would taking a HID setup and reverse firing it into a big reflector do anything (like beam throw, brightness etc?) I've seen a few searchlamps that use this method , including one lighthouse that fired backwards into the reflector.

Any other high powered portable flashlights out there that use this?

 

[LukeA]

I haven't seen anything other than searchlights and Pelican's Recoil LED series which have the light source point back into the reflector.

I also have a 2020 and I also think it's a great light. You should put an SSC in it. I put one in mine (no spacer) and got a floodier beam that still reached further than the stock beam, because of the sheer brightness increase. Just make sure the screw in the negative terminal spring isn't misthreaded enough that it touches the little positive rod inside, which eventually gets hot enough to melt the reflector. (Note to self: call Pelican and order a new part #2024)

 

[Bushman5]

thanks, but forgive my complete lack of knowhow when it comes to elctronics, but SSC?

 

[LukeA]

SSC. It's a higher efficiency LED that still uses roughly the same package size as a Luxeon.

 

[Gunner12]

SSC means Seoul Semiconductor Co. On CPF, it usually stands for the Seoul P4 LED. It has almost double the efficiency of a Luxeon LED used in the 2020 so for the same amount of power, you should get amost double the amount of light with a Seoul P4 LED. The Seoul has a slightly different emitting pattern to the Luxeon so you would need to raise the LED a bit to focus it properly. The Seoul uses the Cree EZ1000 Die that is also used in the Cree XR-E(P4, Q2, Q3, Q4, Q5, in order of efficiency) series of LEDs.

The Rebel 100 is more efficient then Seoul P4 ant it has the same pattern as the Luxeon but it can be very hard to solder since it was meant to be surface mounted.

For the mod, you might also need some thermal compound to ensure a good nonelectrical path for the heat produced by the LED.

 

[Marduke]

The Glo-Toob might qualify for being considered "reverse" fired.

 

[thunderlight]

This might be slightly off-topic, but I have been wondering if a recoil LED setup might be an alternative to some of the heatsinking issues with LEDs. For example, a recoil mod in a Mag would, presumably eliminate the need for a heatsink, since the heat would just disappear out of the front end of the light, that is, the back of the LED.

 

[Flying Turtle]

Not quite "reverse", but the UK 4AA eLED has a somewhat unusual side firing (batwing) LED. While not exactly high powered it is 1 watt and gives a very useful beam.

Geoff

 

[Rob187]

The discontinued Lightwave Infinitron also uses this type of reflector system.

I wouldn't exactly call it high powered though with its 30 lumen output from a Luxeon I.

 

[Gunner12]

This might be slightly off-topic, but I have been wondering if a recoil LED setup might be an alternative to some of the heatsinking issues with LEDs. For example, a recoil mod in a Mag would, presumably eliminate the need for a heatsink, since the heat would just disappear out of the front end of the light, that is, the back of the LED.

That wouldn't really work since air is not a good heat conductor. It would not take away the heat fast enough to prevent the LED form being damaged by the heat, unless you have a well designed heatsink, something like a CPU heatsink. The heat does not come out as infrared so it would not "shine" out the back of a LED. The heat has to be conducted away form the LED, usually by some kind of metal contact.

Since the reflector captures all the light from the LED, doesn't that mean it could theoretically throw further then with a normal setup?

 

[sORe-EyEz]

also, won't a percentage heat be accumilated on the reflector itself? heat transfer would be slower unless the whole reflector & the stem that sits bulb is made of metal.

 

[yellow]

while those lights might be nice,
please think it over again:

You COMLETELY loose the opportunity to use a large and thick heatsink and the opportunity to press mount it to the flashlight body to increase the surface to get heat away (think of the blood, flooding through the hand f.e. Or airflow on bike lights, ...)
but most of all

You loose roughly 1/3 of the light emitted!
that led makes a "V"-shaped light and everything that gets blocked by that remaining, too small heat"sink" or escapes at the back of the reflector is just lost.

Such a setup makes bad lights, noting else
best still is a very deep reflector to catch as much light as possible
- a wide one for flood
- a thight focused for throw

 

[LukeA]

Since the reflector captures all the light from the LED, doesn't that mean it could theoretically throw further then with a normal setup?

It certainly does. The Pelican 2020 with 35 torch lumens can throw about 200ft because all the emitter's light is captured and reflected, none is wasted as spill.

The only problem with such a setup is that a heat pipe is necessary to move the heat away from the LED at currents over ~350mA.