# Crazy-bright little rear vent-light



## Ofroad'bent (Jul 10, 2010)

I just made up a little flashing red light to fit in a rear helmet vent. It's very bright and eye catching, and has only 2 modes, high and 10hz crazy flash. I added a small optic inside the reflector to give a wider beam for better visibility angle.

Here are the various parts:









From right to left- Lens, Little optic to act as diffuser, P60 reflector, Red Cree LED in pill with modified KD driver, plastic cable gland, wire and connector and switch, with heat shrink to cover it all.

I actually used one of EL34's Marwi switches. The parts were all probably under $20, except for the $15 shipping from EL34, which I luckily combined with other stuff.



















Here's the board that replaced the original in the brass pill:









I jumpered it for Hi/Aux 0 and removed one of the power chips to drop it down to around 1100ma.










I use it with a 1S1P battery attached to the helmet.


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## mattthemuppet (Jul 16, 2004)

doh, replied to this post in Deestas thread before I saw this 

looking great though, fits perfectly in that vent. I've been musing about a 2xAAA light for my helmet, using one of those DIY blinking drivers I made...


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## adrenalnjunky (Jul 28, 2007)

Was that built around a blank P60 LED drop-in, or a P60 halogen that you've swapped for LED? I've probably got my old P60 halogen from a Surefire G2 laying around somewhere.


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## Ofroad'bent (Jul 10, 2010)

adrenalnjunky said:


> Was that built around a blank P60 LED drop-in, or a P60 halogen that you've swapped for LED? I've probably got my old P60 halogen from a Surefire G2 laying around somewhere.


It's built around a P60 with red Cree LED. It had 5 modes, but I only wanted the fast flash.


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## Ofroad'bent (Jul 10, 2010)

Forgot to add- set to High/AUXo, and removed one of the power chips for around 1100ma.


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## Toaster79 (Apr 5, 2010)

Ofroad'bent said:


> Forgot to add- set to High/AUXo, and removed one of the power chips for around 1100ma.


I'm always stacking some extra chips on board, never been removing them


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## Ofroad'bent (Jul 10, 2010)

Toaster79 said:


> I'm always stacking some extra chips on board, never been removing them


1100 ma is plenty for a single red XP-E


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## Ofroad'bent (Jul 10, 2010)

If I was to make this light today I'd use a MobyDrv driver with the on-and-flashing mode and a momentary switch.


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## find_bruce (May 8, 2011)

I had missed this thread - I have a similar rear set-up in a flashlight & have been trying to come up with ways to mount it on my helmet. Hadn't occurred to me to simply do away with the flashlight host & shrink wrap the P60 host. I agree with you about the MobyDrv driver


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## Ofroad'bent (Jul 10, 2010)

The full power MobyDrv would require a different LED though- it may fry a single red Cree. You can remove chips or order them with less power, which would work better for a single.


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## find_bruce (May 8, 2011)

According to mattthemuppet you can drive a red XP-E at 2A on copper :shocked:

One of the things I like about the mobydrv is the ability to program the brightness even in the flashing mode. Of course I could be misreading the site


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## Ofroad'bent (Jul 10, 2010)

find_bruce said:


> According to mattthemuppet you can drive a red XP-E at 2A on copper :shocked:
> 
> One of the things I like about the mobydrv is the ability to program the brightness even in the flashing mode. Of course I could be misreading the site


I worry you might blow the LED out at 3A while programming the standard MobyDrv.
Maybe hooking it up to an XML first for programming would be a good idea.


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## mattthemuppet (Jul 16, 2004)

just because you could, doesn't mean you should  You'll get into seriously diminishing returns above 1.5A as efficiency falls off a cliff. If you want moah light, you'd be better off with a parallel triple.

Just order the mobydrv with the power level you want - he can supply them in increments of 350mA, so you should be able to get what you need. There are two brightness options for the flashing modes; full and (I think) 1/3, with the on part being 1/4 of the flash output. Just ask DrJones though, he's very helpful.


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## find_bruce (May 8, 2011)

Mattthemuppet I was worried that your time on flashlight forums had caused you to forsake the one true path of moah power, then you recommended a triple red and my faith was restored


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## mattthemuppet (Jul 16, 2004)

ha! They're pretty nuts on there and crazily willing to try new things, plus they keep building lights all year round instead of just in winter 

I keep meaning to post some pics of the parallel triple update I did to my rear light, but I want to stick an optic on it (it's currently bare or a "mule"). And if I'm going to do that, I might as well replace the driver with a proper driver with fancy on-and-flashing modes and a momentary switch. However that requires me to figure out how to use my flash programmer and I haven't had time to do that 

Still, it's bloody bright as it is!


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## find_bruce (May 8, 2011)

Easiest light I have slapped together. Presently using a 700mA AMC7135 driver, but will replace it with a mobydrv when I have clear in my head what I want



The 1s1p holder is an old 501B host with a tailcap at each end. One end contains the switch, the other is an m12 cable gland, which is a bit of a bodge & I intend to replace it with a remote tailcap.

It got me thinking about whether I can run both lights off the same pack. The front light is a Convoy M1 @ 2800 mAh which has a really nice tight throw. A few options I am tossing around


1s1p x 18650- a similar mod to the switch on the flashlight to power both lights in parallel, & 2 external switches. A trustfire 2400 is most unlikely to deliver 4A (frankly I am not convinced it delivers 2.8A) & even if it did, it would be dead in about 30 minutes. 1 Panasonic 3400 would stretch that out to around 45 minutes.
1s2p x 18650. It would be easy enough to build up a pack like the pics below of my 2s1p. There would be no point in having an empty flashlight body, dso I would probably replace it with an easy2led housing. Only downside to this is that the flashlight has a nice tight throw which I haven't been able to find in the 20mm lenses for the easy2led housing - the 10 degree lenses are acceptable, but not as good.


With my current dynamo set-up I rarely ever run the helmet light on high - it overpowers the bar lights & instead spend most of the time on medium which is ~1100mA. This makes the numbers for 1s1p look a whole lot healthier & even the trustfire 2400 should get around an hour.


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## Ofroad'bent (Jul 10, 2010)

Is there a high efficiency red 3W LED? Something like a red XM-L2?


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## find_bruce (May 8, 2011)

Ofroad'bent said:


> Is there a high efficiency red 3W LED? Something like a red XM-L2?


The Cree Product Characterization Tool has a listing for an XM-L Red, but I have never seen one for sale. No listing at all for any colour XM-L2.

Cree do make an XP-E2 Red that is specced for 1.0A = 2.632 W and 212 lumens in the P4 bin. Cutter have it in a P3 bin which is still specced for a respectable 194 lumens @ 1.0A. Maybe worth trying reflowing it on to one of the noctigon stars that mattthemuppet has been talking about


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## El34 (Jan 11, 2009)

Nice job, I recognize that Marwi external switch. 
Good use for it there.


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## Ofroad'bent (Jul 10, 2010)

El34 said:


> Nice job, I recognize that Marwi external switch.
> Good use for it there.


Yep, it's one of yours.

I would love to have the identical switch in Momentary, with a MobyDrv on 1.5A and a red XPE2 for my next one.


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## El34 (Jan 11, 2009)

I have several switches that fit that housing
momentary and others

I found on mine that I like to put tall switches and boots on them because of using heavy gloves in the winter
makes it much easier to find the switch and push it


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## scar (Jun 2, 2005)

EL34 - your site is not working.


***


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## El34 (Jan 11, 2009)

My host is having issues with all the windows servers
It may be a while before it is up

They have not been able to figure it out yet

Edit: 12:13 est
web host is having huge issues on a ton of servers
Never seen an issue like this in 5+ years with this hostI'll report back here when the web site is up

Edit 09/26
What a bunch of crap that was. web site down for a whole day
Both my web sites are back up this morning


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## find_bruce (May 8, 2011)

Ofroad'bent said:


> Funny, I just finished up an improved helmet-vent red flasher, using a red cree and a 1.4A MobyDrv. Good project for an ice-storm day.


Tease! Where are the details ?


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## Ofroad'bent (Jul 10, 2010)

OK here you go. 
Here are the parts:










From outside to in:

30 degree frosted optic from LED-DNA (I have lots of these now)

Flashlight reflector (optic is sealed in with silicone)
Didn't use a pill this time- hopefully not too much heat with only 1A or so flashing.

Red cree LED - happened to have an older one around but would use XPE 2 if I had one

MobyDrv driver from DrJones - he provided one for 1.4A

Switch from EL34- opened it up and replaced the clicky with a momentary switch to run the MobyDrv.

All soldered up with heat-shrink holding it together. There's a zip-tie for strain relief, I skipped the cable gland this time.
Final wrap with self-fusing silicone tape- may paint some plasti-dip on.















With the MobyDrv I set up 2 brightness levels of on-and-flashing, one for daylight visibility and one for night. One click and it's on daylight, a second click and it's night mode, hold the button and it's off. No taking off the helmet to find which mode I'm in.
I could have added up to 5 more modes- maybe I'll add a very low flash for night trail racing.

Pretty much perfect. Minimal weight, fits in a back vent in my helmet with a 1S1P battery strapped on top and switch attaches to helmet. It would probably go under a conventional seat well too, but not on my 'bent.

Probably $30 total.


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## Ofroad'bent (Jul 10, 2010)

Ofroad'bent said:


> It's built around a P60 with red Cree LED. It had 5 modes, but I only wanted the fast flash.


Anybody have a link to a better red LED that fits in a P60 type reflector pill?
Maybe a red XPE-2, for the ultimate build for next time?


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## scar (Jun 2, 2005)

The first Red LED I got turned out to be amber (can't remember where I got it). Here is a link to the ones I got from Digikey - XPEBRD-L1-0000-00801CT-ND. Nice deep red and super bright at 1 amp :eekster:


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## scar (Jun 2, 2005)

Have you seen these? The guy posts up on CPF as nailbender. May be able to get a CPF discount.

P60 / D26 Cree XPE colors

Here is a link to his thread on CPF - P60 modules -warm, neutral, cool white/XRE-XPE-XPG-XML-U3 / NICHIA 92CRI PART 11 - Page 18

****


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## Ofroad'bent (Jul 10, 2010)

Thanks Jay, but I'm really just looking for a red xpe2 on a little round pad that fits into the pill. Nailbender sells the entire drop-in, which I'd have to disassemble to replace the driver anyway.
Simplest thing would be to find the LED on a 14mm or 16mm round board- doesn't even need a dome.


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## find_bruce (May 8, 2011)

Red xp-e on a 16mm star - no problems eg International Outdoor Fasttech or DX.

Red xp-e2 are a bit more tricky - even cutter doesn't list them. You might have to make mattthemuppet proud and buy the led & star separately & reflow them


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## Ofroad'bent (Jul 10, 2010)

find_bruce said:


> Red xp-e on a 16mm star - no problems eg International Outdoor Fasttech or DX.
> 
> Red xp-e2 are a bit more tricky - even cutter doesn't list them. You might have to make mattthemuppet proud and buy the led & star separately & reflow them


Thanks FB. I'm not in a rush so I'll wait and see if Fastech has the xpe2 in future.
If I need one soon I'll appreciate the links you gave me.


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## find_bruce (May 8, 2011)

Here is an idea to hold a 20mm star - I noticed that there are plenty of cheap flashers running off CR2032 batteries. Here is one example, but there are countless others. A CR2032 battery happens to have a nominal diameter of 20 mm, so I bought one to pull it apart & see if it would work. As you would expect for something cheap, it has just a few simple components








22mm board with 5mm led. The two metal plates are momentary switches - operated by pushing on the front of the lens
CR2032 batteries
Back & strap
Lens to housing seal
plastic that holds the board to the lens
lens
housing front








The inside of the housing is 22mm with a 1mm recess which captures the clips on the plastic.

While the momentary switch would be great for use with a moby drive, can't think at this stage how I could adapt them to a 20 mm star

What I need to do now is make up a heatsink to connect the star to the housing

One word of warning - there are two different kinds of backstraps - an angled version to connect a rear light to a seat post and a straight version to connect a front light to the bars. In the usual cheap chinese light fashion, my white light came with a rear mount.

*Edit* seems like I am not alone - see the DX product forum for a "discussion" with a DX staffer who just doesn't get it


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## Ofroad'bent (Jul 10, 2010)

Looks promising. Is there room for the driver in there?


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## find_bruce (May 8, 2011)

should be enough room as long as the heatsink is not too thick - the cr2032 batteries are 3.2mm thick so you have something like 6.4mm to play with


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## Ofroad'bent (Jul 10, 2010)

OK, ordered one to play with.


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## find_bruce (May 8, 2011)

Just noticed international outdoor now have red XP-E2 on a 16mm copper star


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## find_bruce (May 8, 2011)

Rather than use the waterproof switch with the impossible to solder wires or your diy vent switch I got one of these momentary switches









Low profile, sticks nicely to the side of the helmet, wires are thin but easy to solder, so far it does the job well.


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## Ofroad'bent (Jul 10, 2010)

Didn't know that one was momentary. Which driver are you using?
I got one of those little housings you suggested, and may use this type of switch with that.



find_bruce said:


> Rather than use the waterproof switch with the impossible to solder wires or your diy vent switch I got one of these momentary switches
> 
> 
> 
> ...


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## find_bruce (May 8, 2011)

Ofroad'bent said:


> Didn't know that one was momentary. Which driver are you using?


Front light is using a mobydrv 105C. I have a mobydrv 101 for the rear but I am having some trouble with it - the light works, but I can't change modes or enter programing mode. The switch is connected between batt- & the same leg of the tiny13 chip as shown for the 105C - ie second from left at bottom of this pic







.

Until I sort out the mobydrv 101 I am currently using a simple 700mA driver


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