Found these on Amazon CCYC DC 5V to DC 12V USB Voltage Step Up Converter Cable, Power Supply Adapter Cable with DC Jack 4.0mm x 1.7mm, USB 5V to DC 12V Cable - 5ft. They work to power my PSR-500 from usb plugs in my truck and from my PC. Mind you they are 12V DC so don’t go using these on a 6V item.