What exactly is a flexdrive???

So again, ive been here for a week or so. And although i did read up alot on google as well as around here. Theres still a few things i dont understand.

What exactly is a flex drive? Is it a driver? I was looking at jayrob's DIY pocket mini kit thread and i saw that it comes with a flexdrive. I assumed that was the driver for the LD but i then read a post on the thread that says that you get everything you need to make it except battery, LD, and driver. So i was a bit confused. Would anyone care to clarify for me? What pieces do i need to make the pocket mini? A driver, a battery, a host, a LD, what else?:san:

A flexdrive is a laser diode driver. It's really popular because it can both boost or reduce the voltage.

Also called a buck/boost circuit, it has 4 adjustable output ranges, a good range of input voltages and will output up to 1.5 Amps in special cases.

Mike

A FlexDrive is an adjustable constant current source with the added property that it can act as a DC/DC-transformer. That way, the input voltage does not need to be higher than the output voltage. It is also very efficient, making it useful for battery-powered devices, especially if you want to use e.g. a single CR123 or RCR123 power supply.

Technically, it's most likely not a buck/boost driver (as these invert the output) but a SEPIC converter (I did not analyse the FD in detail yet).

Normally, jayrob sells kits without drivers; but the "HOT" option includes a pre-set driver (the way I understood it).