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Discussion Starter · #1 ·
Hi All,
Thanks for all the great info on this site, i have learned heaps since joining a couple of months ago.

Parts List
1 - 7.4v 3950mah Lipo
These Drivers
Cree XRE R2 and XRE Q5's
These Optics For helmet
And these Optics for Bars
im going to build a couple Amoeba style lights.
my main concern is with the driver I have chosen what switch do I use?
and also can I raise and lower brightness? with a potentiometer???

Can i use a switch like This?
Or so I need a switch that clicks into position? like This? or like This?

Sorry for all the questions

Thanks in advance

Josh
 

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Five is right out
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Those drivers put out varying amounts of current- they don't always do the 800mA as spec'd by DX. Test your drivers before mounting into your housing.

You should use an on/off type switch, not the momentary switch in your first switch link.

If you're using metal tubing for your casing, get the shallowest switches you can find. Most cheapie switches seem to be quite long, which makes them a bit of a hassle to pack into the housing. And I suspect that the square case tubing would be more correctly referenced as "Achesalot style" as I think he popularised the design via his triple LED housing first ;)

Good luck, and have fun.
 

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Discussion Starter · #3 ·
ooops yeah, like the Achesalot style light. it looks like an easy way to get into the DIY side of things. if i run more than 1 LED off the driver do i divide the current by how many led's there are? so 2 would be 400mA 3 would be 266 etc?
should i run each LED off a separated driver?

Thanks

Josh
 

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If you connect the LEDs in series, the same (nominally 800mA for that DX driver but possibly way more) current flows through each. You just burn through your battery Ah faster because of the combined resistance of the LEDs. FWIW, if my experience is any indication, you should get a ridiculously long burn time off your battery pack for 2 LEDs.

Hang on, I just looked at your original post. I don't think you can drive three Crees off one of those DX drivers- the input voltage you need to be pumping into the driver would be around 12.6 volts (3.7V per LED + extra for the driver). I don't think those drivers can boost voltage so you can't use a 7.4V source, nor can you use a 14.8V input without blowing up the driver. Those boards are only suited to one or two Crees.
 

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aka RossC
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The optics that you linked for the bars are not actually designed to be used with cree's as far as i understand. They are made for ssc which have a different dome shape.

My recent hiking light uses those same optics and they are full of artefacts i.e they are very "ringy". It might be possible to play around with the stand off distance between LED and optic to improve the result but I haven't done so.

I don't have a DX alternative to suggest although perhaps a reflector may give a similar beam spread without the rings?
 

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Looks like a good start to the parts. With those drivers and a 7.4v battery, you can run 2 leds, just wire them in series and they will get the same current. you will not be able to run 3 of the leds because the vf of the leds will be greater than that of the battery. I have been running two leds off those drivers for a year now and it works fine, however you will get considerable dimming the last 30 minutes of runtime, or until the battery pcb shuts the battery down.

I think that you can add dimming to the drivers, however it would be a pain to do so. If you are running three leds, you could always have one driver per led, but as stated above, those drivers deliver very inconsistant current from one to the next (from 900-1200 ma from driver to driver) Also, if you decide to use those drivers, make sure that you bench test them and give them 10-15 minutes to run before you put them in the housing. It seems that about 1 in 4 or so burn up in the first few minutes of operation with the battery voltage you are using. If they make it past the initial startup, then you should be good to go. I have found this out the hard way and had to pull lights apart to correct the issue... not fun.

Looks like a good start!
 

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I like bloody ankles
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DX1920 optic

Itess said:
I would use 1920 (which you want to use for helmet) for bars.
+1 for the DX1920 optic on the helmet - great throw, very smooth pattern, snaps on the cree with no glue, and the $1 each price tag !

With some sanding they'll fit well in the 1" square or round Al tubing, not sure if you could sand enough down to get them in 3/4" tube though.
 

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Discussion Starter · #10 ·
thanks heaps for all your comments. My parts are in transit so when they arrive all the fun begins. i may end up getting some other drivers with different outputs, i would like to be able to have a high and low mode.

Thanks
Josh
 

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you can achive a simple high/low mode by using a resistor across the throws of a SPDT switch like this. This light uses a 1000ma driver, but is throttled to 200ma with this 15ohm 2w resistor (resistor values will depend on your setup.) In this case, wires are attached only to the middle and bottom terminals. Throw up gives you low through the resistor, throw down gives you full current.

 

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Discussion Starter · #12 ·
ok for a complete newbie that knows bugger all, how hard is this to do? are any of the switch's in my first post capable of having this done to them?

Thanks
 

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Discussion Starter · #13 ·
Im going to start playing with my lights tonight, i have a couple of questions on the driver. Opposite the red and black leads that are attached to the driver are 2 solder tabs G1 and G are these the + and - to go to the LEDs?

here are also R3, R1, R5 and D1 does anyone know what these are for?

Thanks
 

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aka RossC
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Joshp82 said:
Im going to start playing with my lights tonight, i have a couple of questions on the driver. Opposite the red and black leads that are attached to the driver are 2 solder tabs G1 and G are these the + and - to go to the LEDs?

here are also R3, R1, R5 and D1 does anyone know what these are for?

Thanks
Dx is down at the moment so I can't see exactly what boards they are. However, going from memory..... look at the back of the board. There should be two round tabs that cover the whole back of the board. The middle part or bulls eye section is your positive Vin and the outside ring is the Vin negative.
 

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Discussion Starter · #15 ·
Thanks but im a real newb when it comes to electronics so een what you said is going straight over my head

If you put an 'S' infront of the http you can get onto DX
Click on this link to view driver Link
 

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The red and black wires go to the LED, the pads on the back go to the battery (middle is +, outer is - ).
The others R1 etc are just component labels.

Makes sure you hook up the led before you connect the battery. :madmax:
 

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Good luck, and have fun.

As I sit here writing this, I'm using testing one of those drivers in a new dual Q5 setup with 2 Li-ions in series. Getting 1.46A and, with a fan, the outer casing has reached 31 Celcius (or 88 for the Imperially-minded).
 

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Lets RIDE!
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These drivers have a rep for getting pretty hot, and sometimes putting out more current than advertised, if they're powered by more than 6v. So 2 x Li Ion cells are 7.4v nominal and ~8.4v fully charged....maybe too much. I run my 2 x XR-E Q5 helmet lights off a 4.8v pack, 2 of these drivers parallel off the battery, each driving one LED. I get 900+mA and the heat is OK while moving.....no problems so far. With this setup you can switch each driver separately, giving you high, low, and off options.

My drivers were from a batch purchased 7 months ago. I've read here that some of the newer ones are putting out more current.

The 1920 optic is a pretty tight spot.....excellent on the hat; maybe too narrow for the bars? (but that comes down to personal preference). If you're doing the 1" square tube housings, you should look at the square ledil optics...2 x smooth spot for the helmet, diffused spot + medium for the bars (IMO). You can get them for a good price through Brum's group buy on the CPF forums. The other optic you mentioned is, like Salty said, not designed for Cree LEDs, but can be made to work OK if you're going the DX route. (combined with a 1920 optic it adds some flood and you don't notice it's faults as much as when used alone...might be just right for the bars?)

Have fun!

JZ
 
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