electronicdx Posted August 27, 2004 Report Share Posted August 27, 2004 Hello, I am trying to suppress electrical interference from a power line problem, and I am thinking about building a notch filter for 60 Hz and 120 Hz. Does this circuit connect to the antenna source or the audio amplifier source? How effective would this notch filter do for getting rid of electrical interference? Let me know thanks. this is a nice good looking group! Adam Ebel Glad to be here! Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 27, 2004 Report Share Posted August 27, 2004 Hi Adam,Welcome to our forum.Why do you have electrical interference? Can't you stop the interference at its source?Or are the audio cables that connect your radio tuner to your amplifier simply not shielded?A 50Hz or 60Hz notch filter that is connected beween your tuner and the amplifier, with shielded cables, would remove some hum and some bass, but you will probably still hear the harmonics of the mains frequency. Quote Link to comment Share on other sites More sharing options...
trigger Posted August 27, 2004 Report Share Posted August 27, 2004 hmmm...... such hum may cause by poor DC grounding or the tuner circuit problem.Can't give you much suggestion by now unless we have a chance to look at the circuit or PCB baord. Quote Link to comment Share on other sites More sharing options...
trigger Posted August 27, 2004 Report Share Posted August 27, 2004 You can also check this link in case you are sure the grounding is ok.http://members.shaw.ca/roma/nine.html Quote Link to comment Share on other sites More sharing options...
electronicdx Posted August 27, 2004 Author Report Share Posted August 27, 2004 Thanks for the great replies. I have had this noise problem from a transformer for a very long time, but the guys at the power company would not detect it correctly with their EMF detection equipment. On the frequencies for long wave radio there is dimmer switch like buzz 120 Hz harmonic, its strong on certain longwave radio frequencies and weak on others its even interfering with not just the long wave frequencies 150 to 519 kHz bands, but on the 60 kHz region as well. Strongest detected was 162, 216 and all over others. Now this morning there is stronger buzz its getting worse than it was a 1 month ago. Shortwave is good and FM is fine. everything on AM and LW is nothing but buzz. I wanted to see if I can get rid of the interference from the receiver side and since I am in a townhome location, I just deal with this problem till I move out. The power company would not fix the electrical interference source because its underground. I hope someone can help me out thanks so I can get back into longwave radio station listening. Many Thanks, Adam E. Virginia Beach VA. Hi Adam,Welcome to our forum.Why do you have electrical interference? Can't you stop the interference at its source?Or are the audio cables that connect your radio tuner to your amplifier simply not shielded?A 50Hz or 60Hz notch filter that is connected beween your tuner and the amplifier, with shielded cables, would remove some hum and some bass, but you will probably still hear the harmonics of the mains frequency. Quote Link to comment Share on other sites More sharing options...
surajbarkale Posted August 27, 2004 Report Share Posted August 27, 2004 Put that notch filter afer the pre-amplifier. i.e. just before the volume control. Are you sure it's 120Hz buzz? It seems more like a RF interference. Quote Link to comment Share on other sites More sharing options...
electronicdx Posted August 27, 2004 Author Report Share Posted August 27, 2004 Yes it is its really 120 Hz buzz mostly like a hash buzz. Thanks for the reply. Adam E. Put that notch filter afer the pre-amplifier. i.e. just before the volume control. Are you sure it's 120Hz buzz? It seems more like a RF interference. Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 27, 2004 Report Share Posted August 27, 2004 Hi Adam,Something must be arcing underground. Just hope that it completely fails soon, then they will have to fix it.Of course, the interference is RF, and that your AM longwave tuner outputs it as 120Hz hash.Like I said earlier, a notch filter won't remove the harmonics, which is the hash, but a Comb Filter can, which I think can be made with a switched-capacitor-filter IC.A quick check for "comb filter" at Google showed only about 84,000 hits. There must be some circuits in there. Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 29, 2004 Report Share Posted August 29, 2004 Hi Adam,I found an "ultimate" audio comb filter project for you. It even has measurement results and some mp3 demos. It really works well!Although designed to remove a tone, its author says how to easily change its comb frequencies. The project is here:http://www.ussc.com/~uarc/rptr/emm2a_comb.html Quote Link to comment Share on other sites More sharing options...
login
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.