Understanding AC line filters better - diyAudio
Go Back   Home > Forums > Design & Build > Parts
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 18th May 2008, 05:08 PM   #1
pjpoes is offline pjpoes  United States
diyAudio Member
Join Date: Jan 2005
Location: New York
Send a message via AIM to pjpoes
Default Understanding AC line filters better

Ok so please bare with me here, I'm not an engineer by trade and am mostly self taught, so if any of this is wrong, I'm here to learn. I want to better understand the designing of AC line filters, and how values are chose for each of the components. I understand the role of a Varistor, the good and bad, and how values are chosen for that. It's the actual crossover or filter part.

Using John Risch's AC schematic we see what looks to me like essentially a 3rd order filter. However, because we are dealing with H, N, and G, it isn't something I can make analogous to a speaker crossover. However, I have a better understanding of those, so if someone wants to describe it in those terms, that would be best. We have a CLC filter basically, and I imagine that, based on the impedance of the load, the frequency it cuts off at will change. First question, how are values chosen here, and how crucial are the inductors and capacitors values?

Is there a way to use a simple crossover software to model the frequency of the ac filter? I mean, they both are modulated signals in a way. One is an intentionally modulated signal at various frequencies to make up the musical signal, the other is modulated at a fixed 60hz (u.s. market) for long distance transmission of energy. The goal, I imagine, is to create a low pass filter which removes any RF noise which has entered the line, and would be considerably higher than 60hz, probably in the mhz range. A filter capable of crossing over or filtering much lower and with a steeper slope is preferred I would guess, no? Could I take a crossover software, input the measured impedance of my equipment with not powered up (I know that isn't an accurate impedance), enter that as a ZMA file, and then model a 3rd order crossover to figure out where my values are crossing it over.

Another thing, in the Risch design, he has one basic filter for the whole system. You could, of course, use multiple filters for each outlet, but as a more economical version, could you use a separate capacitor at each outlet for the C4 position. I have a bag of Siemens mylar X2 caps rated for 250vac and .33uf's. I was thinking of putting the .33uf's across the back of each outlet from H to N.

Oh, I think I'm going to know the answer to this in the end, but I will ask it anyway. What is a T-filter or T-network. Tributaries and others talk about having T-networks in their's, and while I think I know, I would appreciate someone else telling me, with schematic if possible.
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
corcom line filters for Aleph 1.2 daly2k Pass Labs 4 21st November 2005 08:34 AM
Understanding interpolated FIR Filters jackinnj Digital Source 0 24th March 2005 12:45 PM
EMI ac line filters & RFI ac line filters. Are they one and the same? KevinLee Parts 1 8th January 2003 12:18 AM
Corcom 3EQ8 Line filters seangoesbonk Parts 3 13th December 2002 04:19 AM
Whats the deal on AC line filters..... hifi Solid State 5 5th September 2001 01:58 AM

New To Site? Need Help?

All times are GMT. The time now is 03:32 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2