The mintyboost is one of our oldest projects, and has evolved to work with more and more products. Here are the differences between the many versions!
(Schematic is essentially the same as the v1.1 but without R4 and R5)
Documented in the process page, this kit used the MAX756 boost chip from Maxim, and could provide about 100-150mA output at 5V. There were no data line resistors for pulling up or down but it worked with most things.
(Schematic is essentially the same as the v1.1 but with an additional resistor slot from D- to ground)
Turns out that some devices wanted two pullups on either data pin, so version 1.2 had an option to use D+'s R5 resistor as either a pulldown or pullup. This version still used the MAX756.
This version worked pretty well for a very long time until about the iPhone 3Gs came out at which point Apple became a lot pickier about 'authorized' chargers.
A 3.3K pulldown R5 was also added to turn off low-power 'boost mode' in the LT1302 chip, this improved high-drain handling at the risk of lower efficiency at low current draw. However, at this point, almost all devices have large batteries (> 500mAh) and require high charge rates.