Using a "Kill-A-Watt" we found that the switching power supply included with the Rift DK, though rated at 5VDC, 1.5A, only consumes 3W of power off of the wall. This signifies that a maximum of 600mA of current is flowing from the AC-DC adapter, assuming 100% conversion efficiency. The USB standard specifies that 500mA is available at the USB A jack for devices to use. Often a computer will provide a little more than 500mA, as the standard mostly exists to warn device developers to not expect more than 500mA from the port. As a result, we hypothesized that the Oculus Rift Development Kit would have no trouble running from a USB port's 5 Volts. Either the port would provide more power than it is rated to, or the Rift would be limited to 500mA yet operate without issues at 2.5 Watts.
To confirm this hypothesis, we soldered a 30 gauge stranded wire from the 5V power pin on the Rift's Mini USB B port to the 5V in on the DC-In barrel jack. We also took the liberty of replacing the obnoxiously bright blue-filtered-to-white-then-back-to-blue LED with a mild green LED. It remains visible, but is not intrusive and doesn't shine through the HDMI port.
The Rift runs perfectly fine off of this USB power. We do not expect fluctuations in draw as shifts based on screen content will be negligible, and the sensors should not draw more/less depending on how much one is moving.
These modifications allow the Rift to be plugged in using only a single cable and single USB Cable, eliminating the need for a wall adapter, a free wall plug, and extra tote space. This makes the Rift a much more portable device.
Back to main index