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aka RossC
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Discussion Starter · #1 ·
I just got some random reflectors from DX I ordered a while ago. I ordered a few smaller ones as well but the 35 mm reflectors got me thinking....

I made the bracket up out of some spare 3mm Al. It is held on with a circlip which is surprisingly solid. I will attatch the heat sink with some AA along with the bracket to try and get rid of a little bit of heat.

For the front, i found these which i will epoxy to the front.

If i use a bare MCE, I should be able to make a super light weight helmet light and the 35 mm reflector should give a fairly tight/punchy beam.

I will run the driver in-line and probably attach it to the back of the helmet with a switch inline somewhere also.

I am just waiting for the MCE to turn up now!









 

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aka RossC
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Discussion Starter · #3 · (Edited)
troutie-mtb said:
:thumbsup: Nice minimalistic light there Looks a bit like an old miners light needs a candle fitting .

Mmm I have some bare MCE ordered and am wondering what they are going to be like to work with .

How you going to wire it .
Probably with sweat on my brow and my tounge sticking out the corner of my mouth as I try not to stuff it up!!!

Thinking 2s2p although (edit) 4p would be even easier....

It sure does look like an old miners lamp.
 

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Spanish biker
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ocean breathes salty said:
Probably with sweat on my brow and my tounge sticking out the corner of my mouth as I try not to stuff it up!!!

Thinking 2s2p although series would be even easier.....

It sure does look like an old miners lamp.
Nice. 1 question, when you say 2s2p what want said exactly, could you put a little schematic picture, please?

Greetings - Saludos

msxtr
 

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aka RossC
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Discussion Starter · #6 ·
PCC said:
Did the heatsink/plug thing come with the reflector? I looked at the DX site but it does not show the heatsink/plug, just the reflector.

I really like that setup. Minimalist and should be a blazingly bright light when you are done with it.
Surprisingly, yes, it did come with the reflector and pill. It didn't show it in the picture when i went back to the site to have a look as well.

Later on, I noticed that gillestugan didn't get them when he ordered them from DX though

http://forums.mtbr.com/showpost.php?p=5170456&postcount=165

Another riddle in the DX lottery :D
 

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aka RossC
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Discussion Starter · #7 · (Edited)
msxtr said:
Nice. 1 question, when you say 2s2p what want said exactly, could you put a little schematic picture, please?

Greetings - Saludos

msxtr
Hi msxtr... I think you describe 2s2p as 2s + 2s - same thing really.

I think this schematic is right for 2s2p but someone please correct me if i am wrong. 4p seems even easier as you don't have to have the pesky wire around the outside of the emitter.

 

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Haha, congratulations for getting the pill, it's like winning at lottery. Isn't that DX in an nutshell.
Your build looks great. So simple yet so good looking. Even better if the heat sink was anodized in a colour matching your helmet, like pink. (just kidding)
Will be interesting to see how it handles the heat.


The wiring in the picture is correct.
Regarding the reflector: I used a 0,3mm spacer between the reflector and the emitter for best beam.

Are you sure you want the 33mm lens?I rather have a larger one to be able to seal from the outside of the rim. Kai aslo has nice coated ones which are sold separately. I have 37.8mm X1.5mm DX lenses if you want one.
 

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Spanish biker
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ocean breathes salty said:
Hi msxtr... I think you describe 2s2p as 2s + 2s - same thing really.

I think this schematic is right for 2s2p but someone please correct me if i am wrong. 4p seems even easier as you don't have to have the pesky wire around the outside of the emitter.

Hi, yes you are right, 2s2p= 2s+2s how I thought :)

Thanks for the pic.

Greetings - Saludos

msxtr
 

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aka RossC
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936 Posts
Discussion Starter · #13 ·
gillestugan said:
Are you sure you want the 33mm lens?I rather have a larger one to be able to seal from the outside of the rim. Kai aslo has nice coated ones which are sold separately. I have 37.8mm X1.5mm DX lenses if you want one.
I ordered the 33mm lens just the other day so i will have a look at it when it turns up and see what i can do with it. The outer end of the reflector has a nice flat surface and if my measurements are correct, I should be able to epoxy it to that surface. At least, that is the plan at the minute.. If that fails, i will move on to bigger lenses as this light is pretty cheap so i can afford to stuff it up a few times.
 

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aka RossC
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Discussion Starter · #14 ·
I have just finished this build and have successfully bench tested.

Big thanks go to Ktronik for his deft soldering (best in town) and help with the driver!

As a refresher, it is running a 2S2P M bin MCE off a Kennan driver at 1 amp (500ma per die). The MCE was a bare emitter which we mounted on a copper slug to give enough stand off so as not to short the MCE terminals on the pill.

The driver is in an external housing (shortened DX torch body) in line with a simple on off switch on the Vin.

The reflector gives a very tight beam (for an MCE) but has the smallest little doughnut in the middle. It is a million times tighter than the Boom SS that I have in the duster so should be just what I am looking for in a helmet light.

Newby warning: This is definitely on the limit for cooling! Without the little RC car heat sink it got hot within 10 second of being switched on. With the RC car heat sink it takes a minute or so in still air. So long as i keep moving, it should be OK. I don't know that i would make one of these and give it to a friend as I am not sure what the MCE longevity is going to be.

I will have a crack at doing some beam shots although it is swelteringly hot here at the moment so I don't know if i can be bothered.
 

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ocean breathes salty said:
I have just finished this build and have successfully bench tested.

Big thanks go to Ktronik for his deft soldering (best in town) and help with the driver!
:thumbsup: No probs buddy, glad it all runs...I take it you DID add the copper slugs to the PT4105 chip on the driver??? its the only real problem with this cheap KD driver as its driven over spec...sadly efficiency suffers due to this fact. To make it better you would have to lower the driver current via the on board SMT 'sence' resistor...but we could not have that now could we... :p

BEAMSHOTS!!!!! We demand!!!

K
 

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aka RossC
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936 Posts
Discussion Starter · #16 ·
ktronik said:
:thumbsup: No probs buddy, glad it all runs...I take it you DID add the copper slugs to the PT4105 chip on the driver??? its the only real problem with this cheap KD driver as its driven over spec...sadly efficiency suffers due to this fact. To make it better you would have to lower the driver current via the on board SMT 'sence' resistor...but we could not have that now could we... :p

BEAMSHOTS!!!!! We demand!!!

K
I AA'd the slugs onto the chip and onto an Al disc at the other end. The AA hadn't quite set as i was assembling so it was jammed into the housing and the mechanical pressure held it while the AA set.

I just ran a visual comparison against a twin R2 helmet light I have been using and it is brighter and the corona looks more usable than the spot optics in the R2 light. Happy days.
 

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That sounds great!
If you have some space left in the driver box I would recommend you to use two PT4105 drivers. You can then run each 2s string on a separate driver, which enables you to adjust current in each driver to a much more healthy level. They run great up to 800mA. At 500mA you can get an efficiency of over 90%. Not bad for such a cheap driver.
It is dimmable with a pot, or you can add a fixed resistor to limit output. This driver is my first choice in many led projects as it is very cheap and versatile. You should actually even be able to make it temperature regulating by exchanging one of the resistors (the R2) with a PTC thermistor.
EDIT: this also requires one extra resistor between output and the pin the R2 is connected to.

If you place a 0,2-0,3mm spacer between the led an the reflector you will get rid of most of the doughnut. Of course you will lose some lumens, but only minimal as the output is very low that far out to the sides. I was not able to see any difference in brightness when I did.
 

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aka RossC
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936 Posts
Discussion Starter · #20 ·
Right.. You had better LOVE these photos.

I got off the lounge in this heat to do them and was summarily devoured by mosquito's!!
Have you ever tried to hold a light still for 4 seconds while you are being rather quickly drained of blood!

anyway.. enough whinging here we go:

No socks tonight... I ran out of hands carrying all the lights..



 
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