I'm not sure but I think if you have a TV/laptop etc. that supports MHL (power over HDMI) then you can use the transmitter without additional power. However, if you don't have this you will need to use a USB cable for power. I hope my answer helped you.

I have a projector connected to an HDMI switch. My question is if I connect this device between the projector and the switch, all my devices should work wirelessly. Am I correct in my assumption?

Thanks in advance for the answer.