Question regarding noise filters

Thread Starter

kenzo42

Joined Feb 26, 2014
34
I have a project that requires a 5v bus. I will be using a cell phone charger for the 5v power source. There's a lot of noise going into the 5v bus so I wanted to add 2 caps (1k uF and 0.1uF) as filters. Would this be the correct way to set it up? Thanks.
20211110_145021.jpg
 

Thread Starter

kenzo42

Joined Feb 26, 2014
34
Yes, but note the proper polarity of the large electrolytic capacitor.

What kind of noise?
This is for an arduino based "smart dehydrator" . Noise is from a fan motor inside a dehydrator. This 5v bus will power a Dallas temp sensor and Dht22 humidity sensor and 3 buttons for a menu on i2c LCD. There are phantom button presses. The project creator used a snubber but also recommended these caps to be used in the 5v bus.
 

MrChips

Joined Oct 2, 2009
25,063
You specified voltage is 5V. You did not specify the load current.

A large value capacitor is not necessarily better than a smaller value.
Two 470μF capacitors in parallel have lower ESR (equivalent series resistance) than one 1000μF of the same material and construction.

It would be more beneficial to place 0.1μF and 10μF in parallel at the electronic load rather than at the power source.
 

Ian0

Joined Aug 7, 2020
4,169
Do you have capacitors across the push buttons? Do you have a sensibly sized pullup resistor on the push buttons, rather than relying on the one built into the processor. I’d suggest 4.7k to 22k.
 
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