I have an Escort 9500ix radar detector which is powered by 12v RJ-11 connector. The stock power cord looks like below:
When I go travel, I want everything(GPS, camera, cell phone, tablet, radar detector, etc.) to be powered by USB so:
1) I don't have to carry the bulky power adapters. (especially when going through airport security)
2) I can use multi-port USB car charger (see below) instead of occupying a precious 12v cigarette power socket for each device.
I have no problem power the Garmin GPS as it uses standard 5V USB port. However the Escort 9500ix radar detector uses 12V RJ-11 port.
So what I need is a 5V-to-12V step-up. I want it to be small and integrated as I don't want to carry different kinds of modules/adapters. Luckily I found one from eBay which looks like a USB-to-DC cable but with the step-up module built-in.
All I need to do is to cut the 2.1mm DC plug off and crimp a RJ-11 connector on. Escort uses the two middle pins of the RJ-11 connector for power. See picture below for pin-out.
The 5v-to-12v step-up cable doesn't necessarily have a consistent color code. Thus you'll have to use a multi-meter to tell which wire is positive and which one is negative. Once identified, insert the wires into the correct slot of the RJ-11 connectors.
The final product looks like below.
What if the cable is not long enough? Easy, get a USB extension cord.
If you don't have a RJ-11 crimper (see below), you may also just cut and strip a regular telephone cord. Then twist it with the step-up cable. All you need is a scissors.