2014-01-04

Interference

Possibly related to my previous post...

In the garage, we have four light bulbs.  Two are on the ceiling, and two are on the garage door opener machine.  Originally all four were incandescent bulbs, and in the previous house they were actually attached to motion sensors so that they only turned themselves on when there was movement in the garage.

Two problems arose: first, the motion detectors got lost and never replaced.  This meant that the lights were burning 24/7/365, the vast majority of the time with nobody in the garage.  So I decided to replace those with compact florescent (CF) bulbs.  This worked fine, sort-of, but you could tell in the winter that they were struggling -- they took forever to get bright, and they were very noticeably dimmer during the coldest parts of the year.

The second problem is that the garage door opener absolutely eats bulbs.  The bulbs need replacing every three to four months.  Along with the damage caused by the vibration every time the opener operates, the sockets seem to attract enough moisture that they rust -- causing connection issues between the sockets and the bulbs.  I couldn't put the original CF bulbs in there because the socket is flush-mounted beside the opener, and there just isn't room for the ballast mostly.  Modern CF bulbs fit, but they still suffer from a high mortality rate (several have physically broken the lighting elements) and from the rust connectivity issue.

So recently I bought some fancy LED lights (at $17 for two 40W equivalents -- that's a huge markup on the cost of CFs, especially now that they've come down in price -- and even that's cheap for LEDs, thank you WalMart).  LEDs work well in both locations, on the ceiling and in the opener.  I would expect that there are fewer fragile parts in the LED light so it would be more vibration resistant.  It starts instantly, even in the cold, and is fully bright no matter what the temperature.

But.

Jenn was complaining that her garage door opener wasn't working correctly.  It would open the door, but not close it.  I figured that the batteries in the openers were done -- they've never been replaced in the 11 years we've had the opener.  So I replaced the batteries in both units.

And the problem persisted.  This caused much head scratching and dis assembly and reassembly of the two remotes.  I could open the garage door from the end of the driveway, but not close it.

So since I was only experimenting with the LED bulb in the opener, I had one old incandescent bulb in one side, and a LED in another.  I pulled the LED to try it somewhere else for some reason, and guess what, the remotes work again.

The only thing I can conclude is that the LED bulb is putting out some kind of radio interference that makes the opener not able to hear the remotes' signal.

So the plan for the garage is now to get a couple of motion detectors, maybe even those big security motion detectors, and fill them with LED bulbs.  That will give us the fast start as well as the low-energy consumption we are looking for in there.  I'll keep an incandescent bulb in the one working socket for now and once they all die just take the bulbs out of the door opener completely and run without them if possible.

But this all got me thinking.

I was explaining to visitors on New Years Eve about my wifi to apple tv problem, and said -- you tell me why it doesn't work, pointing at the separation.  And my guest said, because there are two CF bulbs in the path of the wireless signal?

That stopped me and made me wonder.  There's clearly radio interference from a LED bulb.

Is there any from a CF bulb?

Don't know the answer.  (Neither did my guest, he was just guessing.)

Maybe I'll have to try more experiments with the lights off as well as with the lights on.  I doubt it, since we've had trouble at all times of day with the Apple TV (although admittedly more at night, something we attributed to all the neighbours being home and blasting their WiFi networks).

Not that it really matters now, since we've resorted to the ethernet wire for connectivity.  But it is interesting to think about.