Selection of a resistor and capacitor for making filters in wearable devices?

Joined Apr 12, 2022
13
what is the best combination of a resistor and a capacitor for making filters in wearable electronic circuits?

Sensacell

Joined Jun 19, 2012
3,501
"Where is the best place to live?"

Not enough context to provide any meaningful answer.

What are you filtering?
Why are you filtering?
What are you trying to do?

Joined Apr 12, 2022
13
i am trying to make 50hz notch filter

Joined Apr 12, 2022
13
the first combination is R=47k, C=68nF
The second Combination is R=680 and, C=4.7uF
Which one is best to filter 50Hz and why?

Sensacell

Joined Jun 19, 2012
3,501
the first combination is R=47k, C=68nF
The second Combination is R=680 and, C=4.7uF
Which one is best to filter 50Hz and why?
What is generating the signal you want to filter?

Papabravo

Joined Feb 24, 2006
21,306
the first combination is R=47k, C=68nF
The second Combination is R=680 and, C=4.7uF
Which one is best to filter 50Hz and why?
As you are no doubt aware the solutions are NOT unique. You cannot determine two component values from a single equation. Also you cannot determine an optimal (best) value without specifying something to optimize. The answer to your question is indeterminate.

Audioguru again

Joined Oct 21, 2019
6,782
Your resistances and capacitances were orders of numbers wrong. I corrected them.
Here is an extremely simple 50Hz passive notch filter:

Attachments

• 31.3 KB Views: 15

crutschow

Joined Mar 14, 2008
34,839
If you want a tighter notch than can be obtained with a simple passive filter, than you can use an active filter with an op amp.

Why are you have a problem with 50Hz?
If it's interference from the mains, then you may just need better shielding of the circuit.

Joined Apr 12, 2022
13
Your resistances and capacitances were orders of numbers wrong. I corrected them.
Here is an extremely simple 50Hz passive notch filter:

There are unlimited combinations of resistors and capacitors to filter a specific frequency in the circuit. For example, I am filtering 50Hz from the circuit. There are a lot of combinations of resistors and capacitors to filter out that frequency. If, I make two different circuits of 50hz filter with different combinations of resistors and capacitors. Theoretically, both circuits will remove 50hz frequency from the circuit. Practically, Is there any other effect on the circuit?

MrChips

Joined Oct 2, 2009
31,078
There are unlimited combinations of resistors and capacitors to filter a specific frequency in the circuit. For example, I am filtering 50Hz from the circuit. There are a lot of combinations of resistors and capacitors to filter out that frequency. If, I make two different circuits of 50hz filter with different combinations of resistors and capacitors. Theoretically, both circuits will remove 50hz frequency from the circuit. Practically, Is there any other effect on the circuit?
Pay attention to the source and load impedances.

Audioguru again

Joined Oct 21, 2019
6,782
You did not attach your schematic.
I made every combination of your resistances and capacitors but they do not make a simple passive notch filter.

Attachments

• 48.9 KB Views: 4