In television sets, this high frequency is about 15 kilohertz (15.625 kHz for PAL, 15.734 kHz for NTSC), and vibrations from the transformer core caused by magnetostriction can often be heard as a high-pitched whine. In CRT-based computer displays, the frequency can vary over a wide range, from about 30 kHz to 150 kHz.
If you are hearing the sound, its either a TV or a very low quality monitor. Human hearing in perfect lab conditions can only go up to about 28kHz, and anything higher is not able to be heard by the human ear.
Either that or you’re a mutant with super ears and the US military will definitely be looking for you to experiment on.
I’ll defend this guy: there can easily be a harmonic at half the flyback frequency that is audible. It’s lower amplitude so less loud, but I could believe someone being able to hear that.
Yes, as I previously stated, if there is a problem with the flyback transformer circuit, it is possible that the frequency or volume of the noise it generates can become increased or different.
Though again, PC monitors never made an audible noise unless they were low quality and used the cheaper 15.7kHz transformer in their construction.
Other noises associated with CRTs are the degaussing noise, which only happens once usually after turning on the CRT or after pressing the degauss button, or the sound of old IDE hard disks spinning, which also make a constant high frequency noise.
Not sure you follow: even if the primary frequency is out of range, a harmonic (half the frequency, quarter the frequency, etc) can simultaneously exist with the primary.
I suppose its possible with a low quality CRT that has poor construction, leaving loose parts or thin plastic fins that can vibrate at harmonics of a lower frequency, but high quality CRTs don’t have this issue.
Extra or louder noise does not occur in normal operation of a correctly functioning flyback transformer circuit. Any frequency or harmonic (vibration) that occurs that is not the specified frequency of operation of the flyback transformer is caused by a problem in the circuit. A brand new CRT with known good parts will not have any kind of extra harmonic.
I had to replace a flyback transformer because it was too loud, and it was a pretty simple job. Hardest part was finding a new flyback transformer. After replacement, the noise volume was reduced to normal levels.
There is not one crt I ever encountered that I couldn’t hear. So I’m having trouble believing you information.
I could time it out most of the time, but it was always there.
https://en.m.wikipedia.org/wiki/Flyback_transformer
Under “Operation and Usage”:
If you are hearing the sound, its either a TV or a very low quality monitor. Human hearing in perfect lab conditions can only go up to about 28kHz, and anything higher is not able to be heard by the human ear.
Either that or you’re a mutant with super ears and the US military will definitely be looking for you to experiment on.
I’ll defend this guy: there can easily be a harmonic at half the flyback frequency that is audible. It’s lower amplitude so less loud, but I could believe someone being able to hear that.
Yes, as I previously stated, if there is a problem with the flyback transformer circuit, it is possible that the frequency or volume of the noise it generates can become increased or different.
Though again, PC monitors never made an audible noise unless they were low quality and used the cheaper 15.7kHz transformer in their construction.
Other noises associated with CRTs are the degaussing noise, which only happens once usually after turning on the CRT or after pressing the degauss button, or the sound of old IDE hard disks spinning, which also make a constant high frequency noise.
Not sure you follow: even if the primary frequency is out of range, a harmonic (half the frequency, quarter the frequency, etc) can simultaneously exist with the primary.
I suppose its possible with a low quality CRT that has poor construction, leaving loose parts or thin plastic fins that can vibrate at harmonics of a lower frequency, but high quality CRTs don’t have this issue.
Extra or louder noise does not occur in normal operation of a correctly functioning flyback transformer circuit. Any frequency or harmonic (vibration) that occurs that is not the specified frequency of operation of the flyback transformer is caused by a problem in the circuit. A brand new CRT with known good parts will not have any kind of extra harmonic.
I had to replace a flyback transformer because it was too loud, and it was a pretty simple job. Hardest part was finding a new flyback transformer. After replacement, the noise volume was reduced to normal levels.
deleted by creator
Please don’t tell them about me.
Your secret is safe with me.
On a side note, I can also hear when a capacitor is going bad on an lcd when other people around me cant hear it.
It could be something else in the crts I’m hearing, but I can definitely tell one is on without seeing it. It’s been like this since the 70s for me.
I can also smell and taste things other people can’t, so something is a little different in my brain somehow.
My partner and daughter tell me I have super powers lol. Guess who gets to smell meat for rot? Not them! Bleh.
You’re not alone, I can hear CRTs, bad capacitors and an array of other electrical appliances.
I can still hear the high frequencies that only teenagers and your kids are meant to be able to hear.
I could hear them too, when I was younger. I lost that frequency range of my hearing in my mid-to-late 20’s, which I’ve read is normal.