"When we connect it up to the USB port, an inverting DC/DC converter runs and charges capacitors to -110V," the researcher explained. "When the voltage is reached, the DC/DC is switched off. At the same time, the field transistor opens."
"It is used to apply the -110V to signal lines of the USB interface. When the voltage on capacitors increases to -7V, the transistor closes and the DC/DC starts. The loop runs till everything possible is broken down. Those familiar with the electronics have already guessed why we use negative voltage here."