I hear this noise very loudly from most any standard box television. Haven’t really “listened” for the noise on flat screens or LCD’s yet. I can’t stand this sound. It actually gives me headaches watching TV.
So I want to understand what this is!! A lot of people don’t even hear this sound… what’s the deal? Please…
Thank you!
That’ll be the flyback transformer - oscillating (electrically) at something like 15 KHz or above - the power involved means that those electrical oscillations make things vibrate physically - just like in a loudspeaker - and that physical vibration is sound.
It’s the flyback transformer; on NTSC sets, the frequency is 15734 Hz. Back in my college days, I could hear it too – in fact, I could walk down the hall in my dorm & tell which rooms had TV sets on just from the whine.
You shouldn’t hear the same wine on plasma or LCD sets – the flyback transformer is only used with CRTs. You may however hear a different whine; I sometimes pick up a soft hum from the backlight on the LCD monitor on my work machine, but it’s rather different in volume & tone than a flyback.
Yes, flyback transformer.
The setup for this is actually a great example of a highly refined design. CRT televisions need a frequency around, I think, 17 kHz to drive the horizontal trace. It’s a skewed triangular or sawtooth waveform, and it feeds the horizontal deflection coils on the picture tube yoke. Since this frequency is required anyway, what else would it be useful for? In the decades-old design of televisions, two things have emerged. One is the high voltage transformer that drives the electron guns. Running it at a frequency much higher than, say, 60 Hz lets it be much smaller and still be a sufficient supply, and requires much less expensive capacitance to smooth out the high voltage DC. The other use is to bias the audio amplifier, which is another fairly big user of smooth DC in the TV. So, all three of these are tied together. BTW, it is the mechanical vibration of magnetic parts in the transformer that lets some people hear the squeel, not the fact that that signal also drives the audio amp power supply.
Ah, it’s the flyback transformer.
It always amazes my wife. When I walk in the house I don’t even have to look at the screen to know she left the TV on when she shut off the cable box. It’s a black screen, and it’s not immediately obvious to look at it during the day, but I can hear it. It also used to amaze my father. When I was a kid the Atari 2600 was the big thing, and stores had display models. I could track it down from across the store simply from the harmonic the TV was emitting.
I was so hoping to find it had been invented in the 1920s.
Thanks for the replies!
So why doesn’t everyone hear this sound? I ask my mom this and she doesn’t hear anything. I don’t get it.
I can hear it only if I mute the TV and there is no other noise in the room.
Otherwise the sound from the TV masks it pretty well.
I can hear that sound from a good 50 feet away with the right TV.
I wish I could say the same, regardless of the volume I hear this sound. The thing that gets me is that it’s “wavy” in a sense so it feels like it’s “poking a finger into my brain” or something.
Count yourself lucky it’s just from a tv. I can hear that sound constantly 24 hours a day, the quieter the surroundings the more noticeable it is. I have tinnitus.
High frequency hearing loss. As you get older, the frequency range you can hear decreases. Ability to hear 15KHz can drop off pretty quick. I could hear flyback well through my twenties and into my thirties. I’ll have to have a play with a synth to see what my frequency discernment is ten years on.
Also find out about the Mosquito.
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People’s capacity to hear hight pitched sounds tends to diminish with age (and possibly from damage through exposure to louse noise). There are ‘mosquito ringtones’ available for mobile phones that supposedly only kids can hear.
Wow, funny you mention that! I thought I was the only one! My mom always say’s “how the hell do you sleep with the music on”??? Well, I can’t sleep WITHOUT IT!
I am replying to Vetch. Forgot to quote.