I have one mcp23017 multiplexer to turn LED's on and off, working fine.
I have one 4051 multiplexer to read analog potentiometers - I see the values of the potentiometers in serial monitor reporting stable values, albeit with a jitter of + - 1. This seems acceptable.
The problem is when I send on and off commands to the Leds through the mcp mux, it makes the reading of the 4051 potentiometer values unstable, with a jitter of around 8. This jitter is too much.
Is this because it is causing noise in the power, which needs smoothing, would de coupling be a solution? I am just wondering why when it turns the Leds on and off it causes spikes in the 4051 reading. I'm not sure where to put the capacitors, tried reading many posts but when I put caps between power and ground it isn't making a difference, does the 4051 need decoupling too? I am using a breadboard to prototype on, is that going to be noisy anyway?
please pardon me for beginner question. I will try making my schematic on fritzing to show you.