how to set LED frequency?

Using Arduino General Electronics
11

slipstick:
It's very easy to try it. Then you can tell us how fast a blink rate YOU can see.

Steve

I set delay(13) so I get 38,5Hz, and this is the maximum that I can still see blinking instead of steady light.

So how that device https://youtu.be/opnn7VybOlI could go 300Hz per second?