I’ve bought a cheap digital frequency counter kits. It works great, can measure frequency up to 1GHZ in 19$ only. It use 8 the LED 7 segment display. But it’s a little brighter so cannot clearly read the value.
How to make easy
This films, He request the car store near the house. Select the intensity level of about 60%.
First of all,
Then, Apply the films on the LED display
This is very very tip that my son use it. We not need modify in circuit we can do it, good Luck.