[RFI] Garage door openers

[Roger (K8RI)]

On 8/23/2010 12:48 PM, Sam Morgan wrote:
> A little more background
> We have isolated it to a 110 circuit
> but the night the electrician came out to chase it
> it failed to show up.
>
> However before it started, he was a tad impatient (it was 7:15+ at night)
> so he had gone around throwing breakers, of course none mattered, as the noise
> wasn't present so we couldn't find and isolate the problem.
>
> The only things he did that night that were out of the ordinary were:
> He ran and reset the timer on the yard sprinkler system. Although the times were
> in no way related to the noise start/stop times. AND, he rang the door bell
> which hadn't been used in a year as the house had been empty (but with power
> on). I had always been suspicious of the door bell transformer.....
>
> After that night, the noise was back again, but weaker and more intermittent,
> Normally when it comes on in the evenings, it's on 10 sec and off 30 sec.
> increasing to where 2 hrs later it was on 55 sec and off 5 sec. Then there is
> about 10 min where it is on doe 90s of for 3 sec then it stops for the night,
> always around 9:30pm
>
> Then after a couple of days the noise quit completely for about 4-5 days. No one
> had been in the house to do anything different those days.
>
> Then last night after a glorious few days with out the noise it is back.
>
> To also add to the mix, this noise only comes out in summer when the temps get
> over 85 in the day. It's quiet in winter, this has been the case for the last 2
> years. One year with folks living there and one year with no one living there
> but the power on.

What appears to be apparent.

It turns on and off during specific time of the day.
It's on in the morning for about an hour.
It comes on in the evenings for two to three hours.
The on to off cycle times vary.
It comes on in the summer when the days are hot. (over 85)

First, this sounds like a controller, or control system.  Our air 
conditioner system follows a similar cycle, but not with the 
proportional on/off cycles. Typically a microprocessor controlled, or 
simple set back thermostat will follow similar cycles.  The on off times 
could represent sampling times.  Ours, does not come on often during the 
hottest part of the day  for two reasons. One is the thermostat is set 
higher during the central part of the day and does not reduce the 
setting until late in the day.  The other is the thermal inertial of the 
home. It doesn't reach its peak inside temperature until some time in 
the evening as it's very well insulated.

The varying on/off times are unlikely in an airconditioner as you can 
not turn the compressor on and off for short cycles and motor speed 
controls are usually of the Pulse Width Modulation type. Rather than the 
on/off.   Heaters OTOH often do have that type of on/off cycle. I have 
several small but efficient space heaters, one of which can run up to 
1500 watts that I set on the floor in the front of my old airplane to 
keep the instruments warm in the winter.

But it still sounds like a variable time controller for sampling or 
controlling a lawn watering system.  How about condensation inside the 
controller, or over heating inside the controller. What about the ones 
that sense water need for the lawn. They sense moisture both morning and 
evening.  .. A bad sensor?

Another possibility is a home security system that also monitors 
temperature. Some of these systems go through cycles with time devoted 
to each operation, or section of the system.

Automated controller for a lawn watering system.  They often use the 
variable ratio on/off control with the controller running even when the 
water is off.


Just some thoughts.

> On 8/23/2010 11:26 AM, Ken Winterling wrote:
>> Sam,
>>
>> I haven't run across a garage door opener RFI problem.  Typically, they just run
>> the motor to open/close the door then keep the light on for some time (4 minutes
>> or so).  The rest of the time the receiver is just quietly listening for a
>> transmitter signal.  While it is running I could see it generating some noise
>> but that should only be a matter of seconds while the door travel up/down.
>> Verify with the owner that the ONLY thing he did was open/close the garage
>> door.  Did he turn on/off any lights or do anything else while there?
>>
>> Assuming you have narrowed the RFI to this specific house, have any/all of the
>> following been checked?
>> * A/C system - inside and outside components including condensate pump, if equipped
>> * Heating system (not likely at this time of year)
>> * Electric water heater
>> * Refrigerator/freezer
>> * Attic/gable ventilator fan(s)
>> * Sump pump
>> * Water softener/conditioner
>> * Well pump and/or controller
>> * Alarm systems
>> * Security lights (electronic controls including photo-electric)
>> * Devices on a timer
>> * Defective GFCI outlet
>> * Battery chargers/"wall warts" for all sorts of devices.  Switch mode power
>> supplies are the worst offender.
>> * ???
>>
>> I'm sure there are more but these items jump to mind.  Good luck with your
>> hunting and keep the list posted.
>>
>> Ken, WA2LBI
>>
>>
>> On Mon, Aug 23, 2010 at 12:00, Sam Morgan<k5oai.sam at gmail.com
>> <mailto:k5oai.sam at gmail.com>>  wrote:
>>
>>      It's possible an intermittent local noise problem may turn out to be related to
>>      their garage door(s) opener(s). What part of the opener might be the problem?
>>      How/what might could be done to fix it?
>>
>>      The house is currently empty, but renters will be moving in by next week.
>>      The owner is working with me, but we have previously been unable to find the
>>      problem.
>>
>>      The noise had been silent the last week, but started back up last night. I
>>      called him and ask if he had been at the house and if so what had he done
>>      different. He said he had just been there and opened the garage doors to remove
>>      his work trailer and then closed it back up.
>>
>>      To add another weird aspect of the problem. When it's noisy, it's only 2 times a
>>      day. (with no one even at the house) First for about an hour some time between
>>      12 noon and 2pm. Then again for 2-3 hours starting about 7pm lasting til
>>      about 9:30.
>>
>>      Again I think we have isolated it to the garage door openers.
>>
>>      Any help gratefully appreciated.
>>      --
>>      GB&  73
>>      K5OAI
>>      Sam Morgan
>>
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