 High frequency noise
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Joined: Apr 2003
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axiomite
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OP
axiomite
Joined: Apr 2003
Posts: 5,236 |
File this under knowledge learned in college and since lost.
What is the frequency of that high pitched sound eminating from CRT based televisions? The tv need only be on, not necessarily tuned to any station. Many people can't hear it, but I can, and I've often wondered what frequency that is.
Anybody know? I've googled and come up empty.
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 Re: High frequency noise
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Joined: Sep 2004
Posts: 11,458
shareholder in the making
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shareholder in the making
Joined: Sep 2004
Posts: 11,458 |
19KHZ if I remembr correctly....
::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
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Re: High frequency noise
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Joined: Jun 2003
Posts: 6,833
axiomite
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axiomite
Joined: Jun 2003
Posts: 6,833 |
I have mentioned hearing the same noise to a few people and they looked at me like I was nuts.
Rick
"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud
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Re: High frequency noise
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Joined: Apr 2003
Posts: 16,441
shareholder in the making
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shareholder in the making
Joined: Apr 2003
Posts: 16,441 |
Actually, it's 15,735 Hz, the horizontal frequency of NTSC. The flyback transformer is the culprit.
EDIT: Incidentally you can get this figure by multiplying the number of lines of resolution (525) by the frames per second (29.97).
Last edited by pmbuko; 10/27/05 12:30 AM.
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Re: High frequency noise
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Joined: Mar 2005
Posts: 7,463 Likes: 1
axiomite
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axiomite
Joined: Mar 2005
Posts: 7,463 Likes: 1 |
Peter, you win the "nerd-for-the-day" award.
***********
"Nothin' up my sleeve. . ." --Bullwinkle J. Moose
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Re: High frequency noise
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Joined: Apr 2003
Posts: 16,441
shareholder in the making
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shareholder in the making
Joined: Apr 2003
Posts: 16,441 |
Thank you.
----------
Winner of the nerd-of-the-day award, October 26, 2005
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Re: High frequency noise
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Joined: May 2003
Posts: 2,185
connoisseur
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connoisseur
Joined: May 2003
Posts: 2,185 |
I've always heard it. very annoying...at least my hearing is still good. can't say the same for my memory.
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Re: High frequency noise
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Joined: Jul 2005
Posts: 353
devotee
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devotee
Joined: Jul 2005
Posts: 353 |
In reply to:
The flyback transformer is the culprit.
Further to this, there are also some inductors on the main board with ferrite cores encapsulated in plastic. The ferrite core develops a chip and the voltage running through the coil causes the ferrite chip to vibrate within the plastic casing at a high frequency. This frequency can vary from set to set (when it fails) and is extremely annoying. It usually occurs at a frequency lower than that of the flyback and is more audible (drives me nuts).
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Re: High frequency noise
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Joined: Mar 2005
Posts: 7,463 Likes: 1
axiomite
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axiomite
Joined: Mar 2005
Posts: 7,463 Likes: 1 |
Nice try, Bruce, but you cannot steal Peter's award from him so soon.
***********
"Nothin' up my sleeve. . ." --Bullwinkle J. Moose
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Re: High frequency noise
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Joined: Apr 2003
Posts: 16,441
shareholder in the making
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shareholder in the making
Joined: Apr 2003
Posts: 16,441 |
now that's funny. 
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Re: High frequency noise
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Joined: Apr 2003
Posts: 5,236
axiomite
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OP
axiomite
Joined: Apr 2003
Posts: 5,236 |
Thanks guys...and yes Peter, you get the big dork award this week.
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Re: High frequency noise
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Joined: Jun 2003
Posts: 8,488
axiomite
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axiomite
Joined: Jun 2003
Posts: 8,488 |
You guys are all impressively nerdy.
bibere usque ad hilaritatem
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Re: High frequency noise
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Joined: Jul 2005
Posts: 353
devotee
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devotee
Joined: Jul 2005
Posts: 353 |
In reply to:
Nice try, Bruce, but you cannot steal Peter's award from him so soon.
What!? No consolation prize? Runner up? Gold star?
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Re: High frequency noise
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Joined: Apr 2003
Posts: 5,236
axiomite
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OP
axiomite
Joined: Apr 2003
Posts: 5,236 |
OK...you can have a gold star.
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Re: High frequency noise
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Joined: Jan 2002
Posts: 3,270
connoisseur
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connoisseur
Joined: Jan 2002
Posts: 3,270 |
Peter,
I knew it was about 16 kHz but I did not know you could calculate that from the number of NTSC scanning lines multiplied by the frame-per-second rate. Congrats!
Regards,
Alan Lofft,
Axiom Resident Expert (Retired)
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Re: High frequency noise
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Joined: Apr 2003
Posts: 16,441
shareholder in the making
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shareholder in the making
Joined: Apr 2003
Posts: 16,441 |
I didn't realize it, myself, until the other day when I looked at the frequency and decided there had to be a simple reason for it being what it is.
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Re: High frequency noise
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Joined: Mar 2005
Posts: 7,463 Likes: 1
axiomite
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axiomite
Joined: Mar 2005
Posts: 7,463 Likes: 1 |
In reply to:
What!? No consolation prize? Runner up? Gold star?
How 'bout a nice gold calculator? 
***********
"Nothin' up my sleeve. . ." --Bullwinkle J. Moose
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Re: High frequency noise
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Joined: Apr 2003
Posts: 5,236
axiomite
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OP
axiomite
Joined: Apr 2003
Posts: 5,236 |
Gold Calculator?
OK.
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Re: High frequency noise
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Joined: Aug 2004
Posts: 6,379 Likes: 7
axiomite
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axiomite
Joined: Aug 2004
Posts: 6,379 Likes: 7 |
>>Peter, you win the "nerd-for-the-day" award.
I don't know whether to be PO'd that Peter beat me to it or relieved that I didn't win the prize
M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
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Re: High frequency noise
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Joined: Mar 2005
Posts: 7,463 Likes: 1
axiomite
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axiomite
Joined: Mar 2005
Posts: 7,463 Likes: 1 |
Oh man, Craig, that looks sweet!
Don't tell me that's yours?
***********
"Nothin' up my sleeve. . ." --Bullwinkle J. Moose
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Re: High frequency noise
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Joined: Jul 2005
Posts: 353
devotee
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devotee
Joined: Jul 2005
Posts: 353 |
Whoa! It doubles as a business card holder. Bonus!
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