DIY Xbox 360 Wireless Receiver

[paul_g_787]

I have a whole bunch of Xbox 360 controllers I have acquired slowly over time. All faulty. And I did think I could test them using the USB play and charge Cable to connect them to my PC.
Nope. You need to use a wireless receiver....

While looking on eBay for a USB Xbox 360 Controller Receiver I came across this idea of the DIY wireless receiver, by soldering a USB cable to the RF board salvaged from a 360 console.
I have a bunch of these RF boards laying about from old scrapped consoles.

Have a look at this tutorial:
https://www.instructables.com/DIY-Xbox-Controller-Receiver-for-PC/

There is just one thing puzzling me. What exactly is the need for the 5V Zener diode in series with the USB 5V (red wire)?
All of the tutorials I can find say to use a 5V or 5.1V Zener diode here (check youtube).

I am familiar with using a Zener Diode in parallel reverse bias to regulate voltage, but I am not understanding this use-case. Surely it is just acting as a regular diode here?

Can anyone enlighten me as to the specific need for the Zener Diode?

[paul_g_787]

OK so it does not actually apparently need to be a Zener diode. The use is to simply drop the voltage from 5V to 3.3V to power the board.

I used 2x 1N4007 in series to drop the voltage instead and this is working great, I am getting 3.4V (close enough).