LED Bulbs interfering with Garage Door Opener
Addition of LED bulbs to Chamberlain Garage Door Opener
causes remotes to intermittently fail / stop working
We have a Chamberlain garage door opener of unknown age that was installed before we bought our house in 2011, five years ago. It had two 60 watt incandescent bulbs that came on when the door opened or closed, or when someone walked by one of the proximity sensors in the house near the hardwired control button, or the proximity sensor out in the garage. The door is opened and closed by the hardwired button inside the house, an RF (radio frequency) remote control in each of our two cars, an RF remote control on the workbench in the garage (for when you want to operate the door while in the garage), and a keypad PIN-operated RF remote on the outside of the house. Of course, people are in and out all the time and these bulbs are on and off all the time, and they burn out frequently. Being incandescent, they also waste a lot of electricity.
So I tried compact fluorescent lights (CFL). They use less energy and are supposed to be far "greener" than incandescent lights, despite the mercury they contain. I'm dubious. They are also supposed to last a lot longer. I'm really dubious there, as inside the house they seem to last about the same amount of time as the incandescent bulbs do (very unscientific guesswork), and outside, in the garage door opener, they have a really short life span. I suspect the electronics, I've taken a few apart, and the transistors used in the DC to DC converters that power them look very under-specified. The CFLs also take forever to light up in winter, if they light up at all, and they are dim when they do. All in all, they are useless in this application.
Last week I bought two LED 8.5 watt 60 watt replacement bulbs. They are marked with a manufacturer's name, "OSRAM" I was immediately pleased, they are actually brighter than the real 60 watt bulbs, and all seemed well at first.
The next day people started noticing that the remotes didn't work reliably. the further away from the garage, the less reliable, out in the street, it was very unlikely that the door would operate, even the remote in the garage, and the touch pad remote mounted on the wall near the garage door were not very reliable. It really puzzled me at first, but then I realized that the problem first occurred when the LED bulbs were installed. But how could LED bulbs affect the reliability of a garage door opener? But they didn't affect the reliability of the hardwired button, just the RF buttons. It must be RF interference. From an LED bulb? Of course it was, they almost surely used switching supplies, and they can be very noisy electrically. In fact, I just wrote an article about using a switching supply to run an LED, and my circuit was very noisy, as I mentioned in the article. As nasty ringing at about 8MHz, and a lot of other noise. I didn't mention it in the article, but I hooked a spectrum analyzer up to the circuit, and saw harmonics all the way up to the modest upper frequency I could measure. I took the LED bulbs out of the opener and the problem went away. I put them back in, and the problem came back.
Possible long term solutions
Right now, I have some ordinary 60 watt incandescent bulbs in the opener, but that's not a good solution, in fact, it's the original problem. I could try some 43 watt halogen incandescent replacement bulbs (really, they're still incandescent bulbs, just a more efficient version), but I'm not sure if I'll gain any bulb life that way. I could try other brands of LED bulbs. That very well may work, but trying multiple brands could get expensive on my meager budget. I could use the "problem bulbs", but place them about 5 feet or more from the antenna of the opener, and use ferrite beads on the wires leading to the bulbs. We'll see what I try in the future...