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Comment by rbritton | Hacker News Reader

Failing transformers can cause an incredible amount of RF noise. A couple years ago a failing fluorescent light ballast prevented my garage door opener remote from working until it finally gave out (this was when I discovered it as the cause), and it had enough residual power to maintain the interference for a while even after being turned off.

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(On a much smaller scale) - I had a plasma ball toy as a kid, the kind you put your finger on and the electricity arcs to your finger. One day I broke the glass housing. Curious what would happen, I plugged it in - the radio in the kitchen AND the TV in the living room both simultaneously wouldn't run when the broken plasma bulb was plugged in. I did this several times as a prank on unsuspecting family members and then the unit burned out/wouldn't turn on. I still don't know how dangerous this was to do(if at all).

I have always wanted a plasma globe but have never gotten one because I've been worried about how much radio noise they might generate and if it would interfere with WiFi etc.

My scale wouldn't record my body fat for months until i turned off my plasma ball and it started working again. I was livid thinking it broke.

The most dangerous part of that would probably be being caught by the FCC.

I used to enjoy wrapping a metal slinky around the base of mine. Then whenever I touched metal to it I’d get little sparks. Must have been acting as an antenna, but I wonder what exactly was going on.

It's acting like a capacitor.

Yeah, in addition most cheap(< $200) wireless modules are pretty susceptible to front end overload. If strong enough the RF noise doesn't even need to be in the same spectrum.

Even my 2m Kenwood D710 mobile in my car will break squelch on some drive throughs.

Tesla had a similar issue when someone started taking them too close to radio towers up on the hills. Luckily they were able to build a foil shield so they could get the RFID spot to pick them up.

Neon sign transformers are routinely the cause of such interference as well:

https://www.schneier.com/blog/archives/2016/08/unintentional...

A grocery store has a lot of florescent lights. More opportunities for failure.

IS this why cell signal always seem to be horrible in grocery stores (aside from them being large concrete-block buildings?

That, and the automatic door sensors can be quite noisy.

Steel siding and roofing blocks cell signal, too? My home has aluminum siding and steel roof and until my wife and I got S9's we had horrible reception in the house. Had to install a cell booster with the antenna up on the roof.

> Had to install a cell booster with the antenna up on the roof.

Where can I find such a thing?

In Australia the carriers sell them. I'd start there.

I believe all 4 of the major US carriers also sell or even just give them away. It's in their best interest for their customers to have good signal coverage in a place they spend a lot of time in.

Although these days, with Wi-Fi calling for voice and Wi-Fi itself for data, the need for these devices is lower and lower.

Thanks.

Bugger, those prices! https://www.powertec.com.au/mobile-products/signal-repeaters...

I had one of these for a while: https://www.amazon.com/Wilson-Electronics-Signal-Booster-Off... Worked well enough. Looks like 4G models are more expensive. (No longer need it as I'm with Republic Wireless now.)

Thanks

Most cell providers will give you one for a deposit. I know tmobile does for something like $25.

Ironically the booster that T-Mobile provides causes more issues. Unlike the old ones that brought the signal in from an antenna to the base using some coax, the current models link up the receiver to the amp using unlicensed 5GHZ. This killed my 802.11ac speeds when I had one.

T-Mobile will now send a full femtocell that uses your ISP's net and broadcasts both WCDMA and LTE. It's much better.

AC Linear Transformers effectively are antennas, that is how they induce current in the tapped windings as far as i understand things.

We have lights with newer electronic ballasts and some with the old magnetic ballasts. If you take the tracer part of https://www.amazon.com//dp/B0042VII7A/ you have to be within a few inches to pick up the electronic ballasts. You can pickup the magnetic ones from 10-20 feet away.

(We have the LED's to replace them but finding times to do so is a problem.)

It's usually electronic ballasts that cause more interference since they have an oscillator that runs in the high kHz/MHz, while the magnetic ones don't oscillate at more than the 50/60Hz mains frequency.

Same thing happened to me recently! :)

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