Interference

Bigbear · 26-Jul-2018, 10:35 AM

I hope this is the correct forum .
I have a pair of TV Ears that broadcast in infra red @ 2.3MHz. Lately when my wife plugs in her laptop power supply it interferes with my TV ears. I swapped out the battery pack on the ears to no avail.
Anyone have ideas on what is going on, or where I can go for answers?
TV ears page is no help.

Thanks
Bear

rabbit73 · 26-Jul-2018, 2:39 PM

Hello, Bear

The AC adapter for the laptop contains a switchmode power supply (SMPS). That type of power supply is very efficient, but often radiates interference.

It could be causing interference to the TV Ears or to the TV. Does the laptop adapter cause interference to the TV when the TV Ears transmitter is not connected to the TV?

Bigbear · 26-Jul-2018, 5:48 PM

No it has no affect on the tv. The interference is a recent thing that with this power supply.

ADTech · 26-Jul-2018, 10:05 PM

OEM or aftermarket power supply?

Bigbear · 27-Jul-2018, 10:59 AM

For the computer? OEM Lenovo

ADTech · 27-Jul-2018, 1:17 PM

Hmmm.... Did anything in particular change that was coincidental to the beginning of the interference?

Have you gone in and re-seated any audio patch cords between the TV and the transmitter?

Bigbear · 27-Jul-2018, 2:10 PM

Don't know what happened.Everything was fine until a few weeks or so. I installed new batteries of the TV ears, dusted the transmitter, and disconnected and re connected all the connections.
Wifey does not have another power supply to see if it's the cause.

ADTech · 27-Jul-2018, 2:50 PM

The batteries in the earphone set will not cause this. Because your earphones are infrared from the transmitter, I would not expect them to directly receive the interference from the power supply unless there is a very odd internal failure. I'm more suspicious that the issue is that your transmitter is picking up the noise, either from the power line or via direct radiation.

Does the same interference occur if the laptop power supply is plugged into a receptacle on a different branch circuit served by, usually in a different room?

Is it sensitive to changes in distance or orientation between the power supply and the transmitter.

Trying to determine if the issue is due to conducted radiation (via the home's wiring) or is radiated directly from the power supply to your transmitter or its wiring.

Bigbear · 27-Jul-2018, 3:31 PM

Maybe conducted as it occurs to a lesser extent when plugged in another room. Or not as when in another room the interference seems less and directional. That is I get the interference changes with the orientation of the TV ears.
Wonder if I could put a Faraday cage around the power supply!

ADTech · 27-Jul-2018, 5:51 PM

Try wrapping it with aluminum foil.

Tower Guy · 27-Jul-2018, 7:13 PM

Another trick is to place ferrite cores on the AC input and DC output of the power supply. Sometimes you can find these on used equipment such as VGA cables.