I got my flux pen in the mail today, so I assembled the prototype booster circuit. This circuit uses surface mount components that are as small as 0.06x0.03 inches, and includes a chip with pins that are 0.65mm between pins. Until recently, I didn’t even know these tiny chips could be soldered by hand, but after going through a bunch of tutorials and videos I found online, I decided to give it a go. I first practiced with a few resistors before trying to solder the chip, but all in all, other than being tedious detailed work, it wasn’t so bad. At least, considering how it costs hundreds of dollars to get these done professionally, I’m quite pleased to have done it myself.
So, does it work? I think so. I wired it up to my “test rig” and measured the current draw with my iPhone plugged in. I’ve seen it go over 600mA, and that’s above the crucial 500mA threshold, so it seems to be working. However, with the iPhone drawing 600mA, the data line voltages read 2.5V/1.8V, which is a bit low. If that 2.5V drops any lower, the device might limit current draw to 500mA, or in the case of an iPad, refuse to charge at all. So, it seems like configuring the circuit to output a slightly higher voltage seems prudent (as I concluded in my previous experiment). Unfortunately, I don’t have the right resistor at hand, so I’ll have to wait for my next batch of component orders to show up…
