really REALLY noob question....

[kramer5150]

Sorry in advance for the stupidity of this question... but I am curious...

What would happen if you took your typical Cree P60 module from DX and swapped the XR-E with a Nichia GS? My understanding is that the GS and XR-E have similar Vf specs... if anything the GS is a bit higher.

Will the surplus current output of the DC-DC circuit the GS? Or would the circuit "know" the GS only pulls a fraction of the current of the XR-E.

Since no one really makes a low lumen P60 module I am thinking about making my own. I think a 10-15 Lumen Nichia-GS P60 module with an 18650 cell for SUPER long run times would be very useful as a night stand light. I could do a direct drive/resistor setup, but I want it to be decently regulated. Does anyone make a DIY low current output DC driver board circuit for Nichia emitters?.. something in the 50 milliamp range?

Thanks!!
:thumbsup:

 

[Black Rose]

The forward voltages are similar, but forward current is a different animal.

The GS has a maximum forward current of only 30 mA.

See Page 2

 

[Hondo]

Circuit not know, circuit dumb. It would try to push the GS to the 500-1000 mA plus current that it drives the Cree at, and smoke the GS in short order. I have done the opposite with Seouls, in place of 5mm LED's with good results, more light out with great color, and infinite life of the grossly underdriven Seoul. Someone else may be able to give specific instructions on how to throttle one of the driver boards down to the 20-40 mA range that can be handled by the 5mm LED's. Note that the GS is not one of the more durable Nichia's, and it would be better for a 20 mA drive, the CS and DS are much better suited to a substantial overdrive up to and even a little above 40 mA.

Edit: If you think about what I mentioned above about the opposite mod, you will see that it is the throttling down you want, and the 5mm LED won't do you any good. You will be better off to keep the power LED in place while you adjust the drive current down. Also, with the 5 mm you either get the default Nichia beam from the LED dome-focussing, or you would have to use an MJLED/SMJLED to get the light to the reflector again.

 

[Hondo]

One more idea toward what you want the light to do. I modded in a "16-mode" driver board into a DX module (which happened to come in a Trustfire 801) and on the low mode it pulls only 70 mA. A little higher than the 50 mA you mentioned, but not by much, and it is a very straightforward mod to do. The 16-mode board really isn't. It is three user interfaces, the middle of which is just low-med-hi, and I just leave it there. The other two add all kinds of flashing modes that I never use, and when you add the number of modes in each UI, you get the "16 modes".

 

[Marduke]

DX sells an empty P60 module for DIY work. You could add in your own 5mm and drop resistor to direct drive it off a 18650. If you could find a circuit with low enough output, you could use that also. I think a little 3x5mm cluster would work well, ran in parallel.

The module:
http://www.dealextreme.com/details.dx/sku.3257

 

[mdocod]

Hondo has the right idea, just throttle back a cree to a lower output and enjoy the reliability factor.