# Question about first order highpass filter

#### Kneus

Joined Nov 21, 2013
3
Hi Guys,

I wanna know how to implement the first order high pass filter with 3dB cut-off frequency at 0.05Hz.

For example if I have a 230V AC as input I want to know how to calculate the ouput...

I have tried some methods, but I want to know how you guys would do it because I dont know if my answer is correct.

All help is welcome

THANK YOU!!

#### MikeML

Joined Oct 2, 2009
5,444

#### Veracohr

Joined Jan 3, 2011
772
The output frequency response? Or the output at a particular frequency? Is it a LC or RC filter?

#### #12

Joined Nov 30, 2010
18,224
It always takes at least 2 parts to make a filter, even if one of them is the impedance of the load. You have given us little to work with.

#### WBahn

Joined Mar 31, 2012
29,823
Hi Guys,

I wanna know how to implement the first order high pass filter with 3dB cut-off frequency at 0.05Hz.

For example if I have a 230V AC as input I want to know how to calculate the ouput...

I have tried some methods, but I want to know how you guys would do it because I dont know if my answer is correct.

All help is welcome

THANK YOU!!
How can we tell you if your answer is correct when you haven't given us a clue as to what your answer is?

You haven't even told us what frequency your 230V AC signal is at? 50Hz? 60Hz? 400Hz? What?

If it's at 50Hz, then your signal is two decades higher than your cutoff frequency of 0.05Hz, meaning that you will be down 40dB. Each 20dB is a drop in voltage of a factor of 10, to the output voltage will nominally be 1% of the input voltage, or 2.3V AC.

#### LvW

Joined Jun 13, 2013
1,749
Kneus, have you already a rough estimate om the parts VALUES you need?

#### Kneus

Joined Nov 21, 2013
3
Sorry guys for taking so long to reply...But i will answer your questions with yet another question so you could understand the background of what i am dealing with...

So I have a measurment on a one phase line 50 Hz 230V(RMS)...The measurements are done with a frequency of 200Khz so the values are instantanious values (thats how its called)

Now i have to calculate the Flicker level of line on the measured line according to the data (measured) I have. The data consists of voltage and current values. But to calculate the Flicker we only need the voltage values.

According to IEC 61000-3-11 standard this is done by the following please read this pdf file page 25 to page 30 (chapter 2.4)
http://alexandria.tue.nl/extra2/200911297.pdf

Here they state that in order to calculate the Flicker you have to put the instantanious Voltage values in 5 different blocks.

Block 1 ...constists of calculating the Voltage RMS value over a periode of time measured this is in my case 233V

Block 2 is the quadrent of the ouput of block 1 so 233^2= 54289 V

In Block 3 you need to use high pass filter and low pass filter with all the values needed provided

NOW this where i am stuck i have no idea how to do this ...So i hope you understand now and can help me with this..

THANKS ALOT FOR THE REPLIES AND THIS TIME I WILL BE ON THIS SITE 24/7

Last edited:

#### crutschow

Joined Mar 14, 2008
33,965