Why a cellphone should not be kept near a TV?

[purifier]

Cellphone near a TV

Do you have any idea of high frequency rectifying diodes available in India?

 

[trigger74]

Cellphone near a TV

check this translated page:

**broken link removed**

 

[puviarasu]

Cellphone near a TV

that was a good link trigger

 

[dkace]

Re: Cellphone near a TV

Well I hope someone is watching the original topic...

I don't think that cellphones or TV sets can be damaged. What can happen is the following:

- Cellphones: If you put a cellphone near a magnet, a magnetic head or any other megnetic or electromagnetic field you may literaly reset your phone ! The memory, the program etc. This only applies if you have a strong magnetic field. Because you don't know the variations of this field in the space near your TV that is why you are advised to keep it away form this device. If you check, instractions may say that you have to keep it away from your hard disk , etc. You may also have noticed the following : If you move near a speacker when cellphone tries to connect to the local antenna then an audio pulsewave is heard from the speacker. This bring me to the second topic:
- TVSets: If you move a magnetic, or electromagnetic field near a TV Set then you will distort the electron beam ( always talking for CRT not for LCD or TFT) and the image will be distorted. Many of you may have this "Degauss" button on there TV monitor. It does this : It changes the direction of the magnetic field in the tube in order to change polarity in static electric field on the screen and finally get rid of this field.
Because of the EM field the cellphone creates when in operations monitors are being distorted by this. But you can't harm them at all!

D.

 

[purifier]

Cellphone near a TV

Ofcourse, i'm still watching this topic... That info was very useful... And coming to the site... That one is really outstanding... Now, suppose i want to simulate the circuit in multisim before actually building it up, is there any way i could do all this RF wave hitting the antenna and producing the current and stuff like that in Multisim??

 

[dkace]

Re: Cellphone near a TV

I don't know about Multisim, but the physical property is a variable electromagnetic field. So any alternating voltage sourse can simulate the RF wave as long as the frequency is same as the waves' frequency ( say 1.9GHZ or otherwise check your cellphone) and a coil to simulate the antenna.
D.

 

[paulsimon]

Cellphone near a TV

I do have an interesting experience about Cellar phone & TV. Somewhere in analog cellar phone era. A old color TV is moved to new location and somehow being rotated 90 degree refer to the old place. The color had been mixed up due to earth magnet, believe degauss circuit are gone. By luck, a friend do have a Motoxxx, so try, dial few time to an un-answer no. (cause it ringing), slowly move the color back to normal.
** note, nowadays the digital are less less Tx power. There is a tool for degauss the TV, or simply reconstruct the EI transformer to E coil.

 

[purifier]

Re: Cellphone near a TV

Wow...You have a very interesting tool there... Nice to see that even a cell phone can be used to degauss....

 

[seinfield]

Re: Cellphone near a TV

I tested that if put my cell phone near to a mouse when i am receiveing a call, the mouse pointer moves alone. I tried this again with my wireless mouse and there is no effect.


Regards

 

[purifier]

Cellphone near a TV

Its not working for me... Maybe your monitor flickered not the mouse pointer... Can someone please confirm this? I have a weird feeling... Why should a mouse pointer move? May be the flickering is making us think that the mouse pointer is moving...

 

[dkace]

Re: Cellphone near a TV

Is it an optical mouse or a wireless one?
My guess is that you are using a wireless mouse. These have an rf communication with the PC so it is very possible that some frequncies ( sidebands or main) interfear to the mouse communication.
On the other hand it may be just your screen...moving!

D.

 

[seinfield]

Re: Cellphone near a TV

With the wireless mouse there is no effect, but with a ps2 mouse , the pointer really moves alone when my cell phone is ringing. I saw some flickering on the monitor sometime ago, but it happened with a different cell phone.

 

[glenjoy]

Cellphone near a TV

Of course when somebody is calling you, even SMS, the phone receives and sends RF signal that can induce currents into you cables, that is the reason why your mouse pointer moves.

 

[purifier]

Cellphone near a TV

I'm sorry for reviving this topic. But I'm still not sure about the monitor flickering. Why does it flicker in the first place?

 

[dkace]

Re: Cellphone near a TV

It is basic electromagnetic theory!

ransmitter of cell phone generates ECM pulses that are inducted to cables or can interfere with the frequencies that the monitor is working ( voltage or current)
Simple as that
get it now?
D.

 

[sinip]

Re: Cellphone near a TV

I'm sorry for reviving this topic. But I'm still not sure about the monitor flickering. Why does it flicker in the first place?

Because of bad manufacture process. The thing is, computer monitor should be properly shielded with metal sheets around electronic parts (you should see it through plastic enclosure) and filters on power line and RGB/VGA connecting cable so that no outside EM field can interfere with the electronic circuits and cause picture distortion. But if shilding is not done properly (or not at all) there will be an interference. In extreme cases you could even damage your monitor with GSM phone, or 144MHz two-way radio taken too close while transmitting.

 

[purifier]

Re: Cellphone near a TV

It is basic electromagnetic theory!

ransmitter of cell phone generates ECM pulses that are inducted to cables or can interfere with the frequencies that the monitor is working ( voltage or current)
Simple as that
get it now?
D.

But then, why doesn't the same occur with a Television?

 

[dkace]

Re: Cellphone near a TV

also simple
TV with cathodic tube works on a high voltage electromagnet which directs the electron beam that is produced on the other end of the tube ( on the back of the TV).

The only thing that can disturb the TV and disorient the beam is a magnet in any place around the TV ( try it with the speaker of a stereo in any corrner. You will see that after removing the speaker - which has a big magnet- then colors are fading in that corner).
Cellular is producing an Electromagnetic pulse but is not that strong to disorient the beam- although in some models that produce high power signal this can also occure.

In TFT screens is not only that the electronics controling the screen are influenced b the field, but the screen itself is also subject to that influence. If I am not mistaken, TFT=Thin Film Tansistor sceen is consists of thousends of CMOS FET that are bicolor or tricolor FETS (these are new technology).
If an ECM field is applied in the sourrounding enviroment, and their connections ( Drain pin, Source pin, Gate pin, Substrate pin) then according to Amperes' law a current will be developed in a conuctor. Due to this, the screen is flickering in a certain way, since electronic control is lost for the time that the field is alternating.
If the back of the screen and the sides are well shielded - as mentioned before - then this phenomenon is mostly fading.
I hope I helped. If I made any mistake, please correct it.
D.

 

[purifier]

Cellphone near a TV

WoW! Thanks a lot for that... that explains a lot to me...+1 to you...

 

[sinip]

Re: Cellphone near a TV

It is basic electromagnetic theory!

ransmitter of cell phone generates ECM pulses that are inducted to cables or can interfere with the frequencies that the monitor is working ( voltage or current)
Simple as that
get it now?
D.

But then, why doesn't the same occur with a Television?

Who told you that it doesn't? Just take GSM phone close enough and you fill get nice horisontal bars running across the screen and accompanying audio effects as well.