Why a cellphone should not be kept near a TV?

[purifier]

I'm always asked not keep my cellphone or a cordless phone near a TV or a monitor... They say it'll be damaged by the strong magnetic field of the TV... But my experience tell me something else... Knowingly or unknowingly, i've been keeping my cellphone near a TV for 4 years while charging... The cellphone is working without giving me any problems.... But this contradicts the theory.. Can someone explain what's happening here please? I still don't get why my cellphone is not damaged... Please help...

 

[Sputnik]

tv as a monitor for a cell phone

Sure the TV/monitor has a strong magnetic field, but it is concentrated inside the tube. If it wasn't, don't you think your speakers and computer case would be stuck to the side of your monitor.

The only danger from a TV/monitor is radiation. In which case, keep arms length away from the front of the screen and 5-10 meters away from the sides and rear.

Although, I could be completely wrong,
Sputnik :idea:

 

[purifier]

can you cell phone near a tv

Thanks a lot for that... So, I was wrong.... then let us think it as the magnetic field of the speakers... Why is the cell phone still working? And what do you mean by concentrated inside the tube? What material is used to trap the magnetic field inside the tube?

 

[Sputnik]

Re: Cellphone near a TV

I don't know why the cellphone still works, perhaps it is shielded from it's own radiation and so radiation from another device won't affect it. After all, I think the cellphone gives out more radiation than the monitor.

As for the monitor, just thinking now, I don't think the magnetism is very strong. Think about it, bringing a relatively weak magnet close the front of the screen is enough to distort the colours, so the electromagnets perhaps aren't that strong to deflect the electrons. The radiation is emitted from the electron guns.

Remember, I'm no pro, I'm still in high school and this is all pure guessing and what seems logical to me.

Sputnik :idea:

 

[purifier]

Cellphone near a TV

Atleast that explains to me... Anyway, we'll just wait and see if others have a different answer... Thanks for the reply...

 

[puviarasu]

Cellphone near a TV

Monitor or TV cannot affect any electronics components like cameras cell phones etc. suppose if it can first it will damage because it contains similar circuitries. There is a possibility that your TV or monitor can damage because of cellphone as it emits a high power hi frequency electro magnetic radiation which can induce electricity on an conductor near the phone (you would have seen the blinking LED light stickers for cellphones without battery it works by this principle). you would have seen flickering of monitor or TV screen and noise on audio speaker when you r receiving or dialing or speaking on a cell phone it is also due to this).

 

[purifier]

Cellphone near a TV

So you know about those blinking stickers?? Do you have any idea on how i can make them? Any circuits... Please help...

Coming back to the question... so you mean that the tv doesn't damage the cellphone but the cellphone damages the TV...??

 

[aryajur]

Re: Cellphone near a TV

I don't think the cellphone or the TV can damage each other. The standards set for both take into account the working of each of them close to each other without any harm. One possibility is if the TV set is not so good, maybe the cell phone may give some interference in the TV when the cell phone is being used. Other than that, I don't see any problem.

 

[purifier]

Cellphone near a TV

How can that be? Magnetism is Magnetism whether it is emitted by a TV or a Cellphone.... and what do you mean by standards? IEEE Standards?? If what you say is true then that should give a valid explanation for my question... because even after 4 years neither my cell phone nor my TV got damaged...

 

[aryajur]

Re: Cellphone near a TV

Thats what I said in my post, that neither should be damaged. By standards I mean the radiation standards followed by both the devices. And also a cellphone emits EM waves, not magnetism, which are not strong enough to cause any damage to the TV. The TV does have deflector plates but they are well shielded, so that they do not cause interference.

 

[puviarasu]

Cellphone near a TV

The blinking stickers works on the same principle as the proximity access cards you can get details of it bye searching about the working of proximity access cards with built in chip(no cell).

And I said there is a chance of TV or monitor damage as the EMR of the cell phone is strong (You would have recently heard that it can cause cancer to human also)

 

[purifier]

Cellphone near a TV

Thanks my doubt is cleared... I was confused only because some were saying that there would be no mutual effect and some say either of the two will be damaged...

Do you mind if ask you more about the proximity access cards... I searched in google but i'm getting all commercial results related to Motorola and likes... Many days back i was into the analysis part of these blinking stickers but i could not get any info about them... Now that you've given me an area... i wanted to know if it is possible for me to make a similar blinking sticker myself... Please help...

 

[puviarasu]

Re: Cellphone near a TV

Those blinking chips are SOC's its ckt is big if you want to make it by yourself see the pic it the the basic power supply of the blinking sticker and the proximity id card (in proximity card there will be another coil to send data from the MCU to the main unit)

 

[Sputnik]

Cellphone near a TV

Is it just a coil or is there a metal core. And if I put it near my monitor, will I receive a bit of current? I'm quite keen to build it, how many turns of the coil are required?

Sputnik :idea:

 

[puviarasu]

Cellphone near a TV

If you keep it near the monitor you will not get any current as the field(magnetic) is concentrated at the center of the picture tube at the back end . The given ckt works for higher frequency signals emitted by cell phones and it is air cored of insulator cored as at that high frequency you don’t need any core to concentrate the wave and you have to use a high frequency diode in the rectifying ckt. it is like building a diode radio without any power supply or transistor.

 

[purifier]

Cellphone near a TV

Did anyone make a practical circuit of the blinking LEDs?

 

[trigger74]

Cellphone near a TV

puviarasu is correct.

Some cheap cellphone call indicator just use a high frequency diode and a LED plus a few turns of PCB trace.

It is one of the low-end product I make before.... but I forget the diode partnumber........

 

[purifier]

Cellphone near a TV

Can you describe the complete product with a small block diagram please? I've trying to make the blinking LED for a long time now but due to lack of knowledge in the design field i'm unable to carry out the building process... Please help...

 

[trigger74]

Re: Cellphone near a TV

the diode just rectifying the induced (RF signal by the coil trace) signal and give a DC to power up the LED.

It is not actaully blinking the LED, because the "blink" is the variation on the power of the RF signal received.

Some product will add an small cheap IC and a small battery to do the blinking function .... while the front part is the same.... just to give a logic level to trigger the added IC.

 

[puviarasu]

Cellphone near a TV

It contains some logical ckts as you can see it will have more than one led and blinking in counter kind of fashion.
To test the ckt initially take a coil with a series high frequency rectifying diode and in series with a LED (low voltage if possible). Mostly it should glow