Hi! I've been working at an rtc clock, and i have problems with the brightness. I use a multiplexed display, with a shift register and 4x 2n2222 npn transistors for each digit, but i get flicker effect when trying to use analogWrite function for dimming the light. Is the reaction speed of transistor too slow? Thanks!
Check the video below.
Is the reaction speed of transistor too slow?
No.
The transistor is good for at least a couple of hundred MHz.
Post your program so that we can see what you are doing and how.
Multiplexing and then adding PWM on top can lead to perceived flickering.
Speeding up the multiplexing should help.
Speeding up the multiplexing results in ghosting. Any other way of controlling the brightness?
You must synchronise the multiplexing and the PWM, otherwise you get problems like this.
Any other way of controlling the brightness
Yes controlling the current will control the brightness.
You should post your code.
I had a 4-digit display in a clock which did not visibly flicker:
Also: