Hi Buzzkill,
Nice looking MOD. I'm guessing this thing will be a hit. I've got a few questions that I didn't see answers for on your site.
1) What are the physical dimensions, length and width of the battery tube in millimeters?
22mm Dia. 103mm long
2) How is the voltage varied? Not looking for a real specific answer but... Does the adjustment screw increase/decrease a variable resistor that is placed in the main circuit (such that the full current from the power supply is driven thru that resistor)? Or does the adjustable screw tweek the 'gate' of a more sophisticated voltage regulating circuit that isn't as lossy as a simple resistor in the circuit? (Please don't be offended, just checking).
It is a variable regulator adjustment very little current goes through the pot.
3) Say you set it to 4v with a pair of fully charged batts. As the batts drain, does the output fall off or will the output remain 4v until the pair of batts fails to provide at 4v (+ some headroom)? How much headroom?
It will stay @ 4volts until the low battery circuit activates , It then shuts down the device and a red LED will come ON telling you to change the batteries. in the case of a shorted atty the circuit will decrease the voltage to limit the current and the blue led will DIM to let you know .
4) The site says you get 6v out of a fully charged 2 x 3.7v stack. Where'd the extra 1.4v go? Does the battery stack need to provide 1.4v headroom over the desired output in order to achieve that desired output?
It is dropped across the regulator , with 7.4volts when you set it to 3.6v the regulator handles the rest of the voltage.
5) How efficient is the voltage regulator? So how much battery power is consumed by the regulator vs being fed into the atty? And how does the variable adjustment affect that ratio?
the efficiency changes with the set point voltage, the higher the set voltage the more efficient the device is . ( less voltage across the regulator)
Thnx!