Mendel USB and power connector
This page describes how to get power and USB into your Mendel from your computer.
Mendel needs as 12 volt power supply capable of supplying at least 5 amps. You can either buy a power brick with that specification, which will be expensive but neat, or you can hack an old PC power supply, which will be cheap but slightly scruffy. You can also run Mendel off a 12 volt car battery, or the 12 volt power socket on a car dashboard.
The standard Mendel 12v power connector is a 3-pin XLR connector.
You'll also need a USB to TTL converter. It is possible simply to buy a USB to TTL cable here.