Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Where and what do you plug into the usb/power? Something must power this devlish this.
Document: i ordered this converter to convert my satelite to hd. at first the picture wasnt very good but after adjusting my picture settings on my tv it looks great. it come with a power cord but i used a usb to plug it into my tv.
I searched a long time to find some way to hook up my Apple TV to my TV with RCA jacks (Red, White, Yellow). This product works. The picture is okay but not great. The unit comes with a usb cord for power. It does not come with the wall plug necessary to plug the usb cord unto. Fortunately I had one laying around the house.
right from the start these units would work for a while and then stop, i thought it was the converter but then discovered it is the power supply that comes with the unit, we bought two of them and had to replace both usb power supply units. - easy to just use another usb power supply and cable from another device but too bad they are not made better.
Can't get picture to my tv. I tried using this to plug my NON-HD DirecTV box into my new XBOX ONE and messed around with it for an hour or so but couldn't get picture. Don't know if it's the unit or if I'm not doing something right.
Arrived promptly and was very easy to install (self-explanatory, really) though make sure you have a USB port for power. However, while the converter lights up (has power) and my Samsung SmartTV recognized that something is plugged in, it says there is no signal from my Nintendo 64. I will try another composite device and update this review later.
Hit and miss reliability even for a tech savvy engineer. Using to plug VCR into surround sound HDMI port. Only works at 720P and must restart surround sound unit to detect. Picture quality is poor.
I found it kind of strange that the converter did not simply have a plug for the power directly. I can understand the usage of USB, but why not just have USB to USB?
The product  arrived on time in excellent work in order no problems easy to set up just plug it in turn on the power. This a great solution if you have a composite device and want to display it on a TV or monitor that has HDMI input.
If you want to Connect RCA composites into HDMI port, this will do the job.Plan on having a USB port or socket available to power the unit. Plug into the monitor with the HDMI, plug the RCA cables in and the unit works. A good solution for older components to tie into new televisions.
this looked like a great deal for the price but the unit doesn't sync with any of my devices properly and just turns theTv screen green. When I first plugged it in it was all green and I thought it was with the display settings. It then worked for a week or so and the power went out and it just turns everything green again. when I plug things directly into the hdmi on the tv they work fine, but this thing just makes everything green and is completely unusable.
Answer: Comes with USB cable you plug into any USB source.