I'm sure there's a scientific explaination.

**osci** · 26-05-10, 08:06 PM

I was talking to a mate at work yeserday about satellite dishes, he knows I'm into electronics ect.

He told me that he's been having trouble with one of the two air conditioners he had installed in the upstairs rooms in his house.

He said exactly the same brand air cons, installed in two different rooms, one has been working perfectly, while the other has had regular problems with the remote control....

He said at times, he cannot turn it on/off with the R/C, at other times he can turn it on but cannot turn it off and vice versa.

He said each time service technicians were called out to investigate they could not find any fault with the air con unit itself or the remote control., so basically they were resigned to switching on/off manually

He said on a Sunday night back in summer, there was a blown globe or more accurately a blown energy saver globe, this was changed, and for some reason they decided to switched air con on with the remote and low and behold from that sunday night, they have not had anymore issues with that air con units remote control.

any explainations anyone?

**Fernbay** · 26-05-10, 08:21 PM

The inverters inside the CF globes can go faulty and corrupt the IR remote signal. The problem is not uncommon

Ive pulled them apart before & found the electrolytic cap swolen with it's top splitting. Replace the dodgy cap & off they go again

**Learjet** · 26-05-10, 08:54 PM

Yep, what Fernbay said. Was reading of a similar problem just the other day myself.

**fandtm666** · 26-05-10, 08:59 PM

thats interesting , something to remember

**osci** · 26-05-10, 09:21 PM

I said to him that it could be some kind of interference from the globe itself but I said to my knowledge of such as is very limited, but it did make sense when he stated the when the technicians attended to check the equipment out this was generally during the day and hence no lights were needed. but thanks dudes!!

**Fernbay** · 26-05-10, 09:31 PM

**trash** · 26-05-10, 09:43 PM

This one is not so complex when you know how IR remotes work.

The first thing to do is look at what the CFL and the AirCon RC have in common.
It may seem like nothing at all. The RC uses Infra Red and CFL mostly a blueish white light.
BUT, when we look at the IR optical components we discover that the opto-transistor is also sensitive to white light as well as IR. It's the weak link.

So how to IR RC's work in daylight if the bright light of day floods the IR transistor ?
How does a candle, which puts out lots of IR also not jam an RC ?

The remote control uses a subcarrier on Infra Red to filter out all other signals.
Only signals with a 38KHz carrier will be detected, all other frequencies will be rejected.
Then it's only a matter of OOF (On-Off-Keying) the codes on the 38KHz carrier to get the signal on and off.

So how does the CFL's signal get past this 38KHz carrier ?
Well inside the CFL is a tiny little switchmode power supply. They don't operate at 50Hz.
Instead they convert the 240VAC into DC and then convert this DC to a high frequency AC so that tiny transformers can be used in place of big heavy 50Hz transformers.

Care to guess what frequency the CFL's PSU works at ? It's not precisely controlled and can be vary greatly, which is why some CFL's and not others may cause the problem.
So that CFL's PSU was running about 38KHz, it was switching the tube on and off at 38KHz flooding the room with the signal and jamming the remote control.

**iwacelect** · 27-05-10, 10:10 AM

see this ssooooo often in the trade it's not funny,

when ever we get a call "my remote just stopped working" our first question

"is there any cfl's in the room....
there is, go switch it off and try again....
there you go....
what...
how does it happen?.....
do you have an engineering degree...
well i'm not going to waste my time teaching you electronics, as without a good knowledge of electronics and light your not going to understand anyway....
how do you fix the problem....
CHANGE THE CFL...
no, theres nothing wrong with the unit so we dont have to come out...
no, it doesn't need to be exchanged...
CHANGE THE CFL..."

click

**osci** · 27-05-10, 12:29 PM

Originally Posted by trash

This one is not so complex when you know how IR remotes work.

The first thing to do is look at what the CFL and the AirCon RC have in common.
It may seem like nothing at all. The RC uses Infra Red and CFL mostly a blueish white light.
BUT, when we look at the IR optical components we discover that the opto-transistor is also sensitive to white light as well as IR. It's the weak link.

So how to IR RC's work in daylight if the bright light of day floods the IR transistor ?
How does a candle, which puts out lots of IR also not jam an RC ?

The remote control uses a subcarrier on Infra Red to filter out all other signals.
Only signals with a 38KHz carrier will be detected, all other frequencies will be rejected.
Then it's only a matter of OOF (On-Off-Keying) the codes on the 38KHz carrier to get the signal on and off.

So how does the CFL's signal get past this 38KHz carrier ?
Well inside the CFL is a tiny little switchmode power supply. They don't operate at 50Hz.
Instead they convert the 240VAC into DC and then convert this DC to a high frequency AC so that tiny transformers can be used in place of big heavy 50Hz transformers.

Care to guess what frequency the CFL's PSU works at ? It's not precisely controlled and can be vary greatly, which is why some CFL's and not others may cause the problem.
So that CFL's PSU was running about 38KHz, it was switching the tube on and off at 38KHz flooding the room with the signal and jamming the remote control.

thanks Trash!!!!! ...... thats makes it very clear

**osci** · 27-05-10, 12:30 PM

Originally Posted by Fernbay

I wouldn't have been any the wiser had you not posted the graphic...much appreciated!!!!

**Skepticist** · 28-05-10, 12:04 AM

Had this very same problem years ago when a new TV was placed in the lounge (just happened to have one of the early CFLs in there also) and the remote control was initially suspected. I just happened to have a simple little IR detector I'd made years before when experimenting with the idea of making my own universal remote and when I pointed it at the CFL it went crazy on the amount of IR hash coming from there. The detector didn't isolate the 38kHz carrier, it simply responded to any IR radiation of sufficient amplitude and was based on an IR receiver salvaged from a defunct PC mouse. Changing that lamp to an incandescent was what completely fixed the problem and in later years changed it back to a CFL but the problem is gone these days. They still seem to produce excessive IR hash but perhaps they're generally designed to run at a frequency clear of the remote range these days and many seem to be in the audio range now as I can hear most of them when the house is quiet.

Re the mains cap failing mentioned by Fernbay, I've had more than a reasonable number of those fail dramatically here (KABOOM) in a batch of lamps I got cheaply (you get what you pay for as always). A couple exploded with enough force to shatter the base, break the wiring to the tube and launch the tube assembly a nice distance before it smashed on the floor. Heard a tale suggesting CFLs were originally designed to run oriented in any direction other than pointing down as most incandescent lampholders are mounted. In the downward mounting that cap (electrolytic) overheats and dries out quite quickly leading to disaster or at least a much shorter than rated life expectancy.

**RHCP** · 28-05-10, 01:33 AM

Years ago (before CFLs) i had a set of IR wireless headphones. You could hear the interference from most light bulbs.....if you got too close to the window you could no longer make out the music (IR from the sun). It was somewhat interesting, as you could stand in one place which was well lit and it would be fine, take a step to the right and it would go bonkers for no apparent reason lol

Cheers.