Which Driver Board for 3v light?

[Curly]

With all the choices of driver boards I have seen (mostly DX or KD) I am now confused. Some are boosted, some are not. Not sure what I need so here's the scenario:

Cree Q5 in single 3v cell light. Alternatively, Q5 in single NiMh light.

No Modes (they are annoying) I'm old school - light or no light...

It needs to be of normal size - 16 or 17mm I think.

I would like a circuit that will keep light output steady (as possible) until the cell is drained. I understand that as the cell drains, voltage from it will drop. That means (to me) a driver board will need to maintain voltage and/or current over the duration of the voltage drop.

This is a little different from the above quest:

So far I have used the 3x and 4x 7135 boards from DX in my C8 (single 18650) with Q5 emitter. I didn't notice any difference in output using the stock or these other two boards. I find that in itself very odd. Leads me to think they are not very good, or work as described.

Maybe I should have made two threads...

Thanks for your help!

 

[Mr_Light]

These seem to work well with 2 D cell Alk or NiMH cells. Note the latest boards are blue and have small + an - signs next to the solder pads.

AA and 14500 Circuit Board for 3.7V LED Emitters 3-Pack (1.5V~4.2V Input) $6.46
http://www.dealextreme.com/details.dx/sku.4735

 

[koala]

If you don't mind dx long processing time, terrible circuit
efficiency and prefer something low cost then sku.4735 is
extremely attractive.

Otherwise, head to cpf dat2zip Sandwich Shoppe and choose
either Madmax, Badboy, Nexgen or GD(if you wish to use RCR123).
The boards puts out guaranteed current so you know what you
are getting. The converter boards are also well documented,
so you will be less likely to run in to wiring problems. Most
Sandwich Shoppe boards(except Madmax) are based on high
performance Texas Instruments power controllers, they are
not stinkin 1990s chipsets like sku.4735.

 

[Curly]

Maybe those Sandwich Shop boards are better... sure looks like it. There are so many though which makes it hard to pick one. Do I get one with lower voltage in like the 1.5v ones for AA battery, then get the 3v minimum for the 18650 application?

Those "badboy" boards don't make much sense since they are not tested. I hope the other ones are.

Thanks for the info.

 

[wechnivag]

what about this board? will it work with 3V input? it seems pretty efficient, the review quoted 90+ %
http://www.dealextreme.com/details.dx/sku.3256

 

[koala]

what about this board? will it work with 3V input? it seems pretty efficient, the review quoted 90+ %
http://www.dealextreme.com/details.dx/sku.3256

Unfortunately that's a buck circuit. Curly needs a boost.

 

[koala]

Madmax will work with 1.5v and 3.0v so there is no need to get two boards.

18650 has a voltage range of 3.2v(discarged) to 4.2v(fresh), so you will need a buck and boost. A GD will be a good candidate. So you get two seperate boards instead of three.

Which "badboy" boards don't make much sense??? I am confused.

Maybe those Sandwich Shop boards are better... sure looks like it. There are so many though which makes it hard to pick one. Do I get one with lower voltage in like the 1.5v ones for AA battery, then get the 3v minimum for the 18650 application?

Those "badboy" boards don't make much sense since they are not tested. I hope the other ones are.

Thanks for the info.