Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Q&A

Comments on Band pass filter given cutoff frequency and bandwidth

Parent

Band pass filter given cutoff frequency and bandwidth

+0
−6

I have decided to try design a band-pass filter with a cut-off frequency of 10kHz and bandwidth of 2 Hz.

Image alt text

$$ \frac{1}{\sqrt{LC}} = 10001 \rightarrow LC = 1/100020001 sec^{2}$$

$$ \frac{R}{L} = 2Hz$$$$ \frac{1}{RC} = 2Hz$$

Here is what I have done but if I plug the values to WolphramAlpha

it says it doesnt have any solutions.What am I doing wrong?

History
Why does this post require attention from curators or moderators?
You might want to add some details to your flag.
Why should this post be closed?

4 comment threads

What's the purpose? (4 comments)
Unreadable image deleted. (2 comments)
Equations (1 comment)
"Bandwidth"? (1 comment)
Post
+0
−4

My mistake was taking the third relationship $$ \frac{1}{RC} $$ which says how to find the bandwidth of a parallel RLC filter but we have a series RLC filter.

Now solving the system : $$ LC = 100020001 , \frac{R}{L} = 2 $$

gives us the correct ratio between C1 and R1 and L1 with more detail:

C1:L1 = 100020001:1

C1:R1 = 100020001:2

History
Why does this post require attention from curators or moderators?
You might want to add some details to your flag.

2 comment threads

At least now will you say what it is for? (5 comments)
Radians per second are not hertz. R/L is actually \$4\pi\$. You have inadvertently chosen to... (1 comment)
Radians per second are not hertz. R/L is actually \$4\pi\$. You have inadvertently chosen to...
Andy aka‭ wrote over 2 years ago · edited over 2 years ago

R/L is actually $4\pi$. You have inadvertently chosen to work in radians/sec but you didn't convert Hz to rad/sec. Rookie error. Also, you didn't appear to understand that the basic relationship involved is this: $Q=\dfrac{1}{R}\sqrt{\dfrac{1}{LC}}$ and, Q is centre frequency divided by bandwidth = 5000. If you approached it more formally (as per what I have just written) then you demonstrate understanding rather than cobbling together some half-eaten formulae taken from some unknown place.