Tiny current source circuit for 5 LED Headlamp?

The application is a Petzl Zipka that starts out with 3 White LEDs. I was planning to mount 2 more LEDs in the housing. Ideally I'd like to be able to vary the light output from low to max (30mA) via potentiometer. If this is not easily done, the lamp can be at max all the time.
This lamp is very small, so a couple of small (TO-92) components could fit, but unfortunately not the LM2621 evaluation board.
Which reg should I choose?
LM317L Voltage Reg, Zetex ZXSC300 or LM334Z Current Reg? Others?

What I need help with is component selection and a simple schematic including resistance values. I have a digital camera and will document the conversion for the greater good.

The Zipka is a nice light, really compact and convenient. It's very well engineered from an ergo perspective. I like the high-tech cordreel. If I could just stop it from getting dim 1 hour after I change the batteries!

Thanks, Greg

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by meboe:
The application is a Petzl Zipka that starts out with 3 White LEDs. I was planning to mount 2 more LEDs in the housing. Ideally I'd like to be able to vary the light output from low to max (30mA) via potentiometer. If this is not easily done, the lamp can be at max all the time.
This lamp is very small, so a couple of small (TO-92) components could fit, but unfortunately not the LM2621 evaluation board.
Which reg should I choose?
LM317L Voltage Reg, Zetex ZXSC300 or LM334Z Current Reg? Others?
<HR></BLOCKQUOTE>

The ZXCS300/310 is not a current controller. I just try to figure out how the circuit which our CPF experts in the Zetex thread are designing really works. In every case it is a very efficient booster and designed to drive a Luxeon Star with about 350mA.

I would suggest making a booster with the LT1932 from Linear Technology which is very small (SOT23) and a real current controller. The LT1932 could do a very good job in the Petzl Zipka/Tikka even it has not the same efficiency as the 'CPF Zetek circuit' and is able to drive 4 - 5 LED's with 40mA or some more LED's with a lower current.

You will find the application design in the datasheet at http://www.linear-tech.com/prod/datasheet.html?datasheet=771.

In every case I would recommand choosing a current controlled booster for driving white LED's. Then you can switch the LED's in series and all of them have the same current. Such a booster will provide a much a higher output voltage to get the necessary current.

Switching the LED's in parallel isn't safe enough because the LED current can vary much. Eg. on 3.6 volts one LED may have 20 mA and another already 40mA, Quit a big difference which could be dangerous for the LED's.