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Beacon Light Synchronization  
User currently offlinecotparampguy From United States of America, joined Jul 2008, 228 posts, RR: 0
Posted (3 years 8 months 1 week 1 day ago) and read 4321 times:

From what i've seen, usually the beacon lights on A320 series and the 737NG series usually blink at the same time with each other. On some aircraft however, they blink seperately. What causes this difference between the same aircaft? Is this a computer operated function or just a worn type of relay?

10 replies: All unread, jump to last
 
User currently offlinefr8mech From United States of America, joined Sep 2005, 5658 posts, RR: 15
Reply 1, posted (3 years 8 months 1 week 13 hours ago) and read 4176 times:

Power up time. Age of the tube or power supply. Whether the strobes share a power supply or timer. Any number of reasons.


When seconds count...the police are minutes away.
User currently offlinespchamp1 From United States of America, joined Apr 2010, 87 posts, RR: 0
Reply 2, posted (3 years 8 months 6 days 4 hours ago) and read 3959 times:

I have noticed that myself as well on our (B6) A320's. One explanation was that there are actually two bulbs in each housing. A primary and a backup. If the primary goes out then the secondary will kick in and perhaps because of some type of bypass they will blink slightly out of sync.

User currently offlineRJLover From Canada, joined Dec 2006, 578 posts, RR: 1
Reply 3, posted (3 years 8 months 5 days 22 hours ago) and read 3898 times:

I've always like the beacons on the CRJ that blink opposite to eachother (top, bottom, top, bottom, etc).


Last Flight(s): YHZ-YUL-YOW-YWG-YVR // YVR-YYZ // YYZ-YUL-YHZ
User currently offline413X3 From United States of America, joined Jul 2008, 1983 posts, RR: 0
Reply 4, posted (3 years 8 months 5 days 6 hours ago) and read 3778 times:

747 follows a pattern of slowly going in synch then alternating. Pretty neat.

User currently offlineWoof From , joined Dec 1969, posts, RR:
Reply 5, posted (3 years 8 months 3 days 19 hours ago) and read 3573 times:

Quoting 413X3 (Reply 4):
747 follows a pattern of slowly going in synch then alternating. Pretty neat.

I think I have exactly the same system on my Alfa Romeo.

More to the point, I've often wondered the same as the OP.


User currently offlineshamrock137 From United States of America, joined Jul 2005, 168 posts, RR: 0
Reply 6, posted (3 years 8 months 3 days 17 hours ago) and read 3505 times:

Quoting 413X3 (Reply 4):
747 follows a pattern of slowly going in synch then alternating. Pretty neat.

This is not necessarily a design feature, but instead most likely because the top and bottom beacon use two seperate strobe power supplies. Because each power sullpy is designed to flash at say for example a one second interval, the strobes may start off flashing in sync but slowly go out of sync due to tiny differences in each flasher module, but eventually they will sync back up, and again go out of phase. On the other hand aircraft such as the 737 and 757 most likely share a power supply for both lights, this meaning that they flash at the same time. Taking it a further step, Airbus has complete synchronization between all the flashing exterior lights. All the white wingtip and tail lights will flash, then just the wing tip, then the red beacon lights. Im not 100% sure, but I once head that this makes it easier to determine of the plane is coming towards you, or heading in the same direction. If you see the double flash of the wingtip, vs the single flash of the tail, you know which way the aircraft is facing without having to see the position lights. The MD-11 has a similar pattern for its lights as well.



Time to spare? Go by air!
User currently offlineT prop From United States of America, joined Apr 2001, 1029 posts, RR: 1
Reply 7, posted (3 years 8 months 3 days 5 hours ago) and read 3404 times:

On some aircraft when there are separate power supplies, the connecter on each power supply usually will have a pin in the connector terminal for sync. If the strobes are to be synched, these pins will be connected between power supplies.

User currently offlinebond007 From United States of America, joined Mar 2005, 5455 posts, RR: 8
Reply 8, posted (3 years 8 months 2 days 15 hours ago) and read 3307 times:

Quoting shamrock137 (Reply 6):
This is not necessarily a design feature, but instead most likely because the top and bottom beacon use two seperate strobe power supplies.

It's probably less dependent upon power supplies, but purely on whether they are synced electronically or not, because as you say ..

Quoting shamrock137 (Reply 6):
but slowly go out of sync due to tiny differences in each flasher module

Which will happen regardless of shared of separate power supplies.

Quoting T prop (Reply 7):
On some aircraft when there are separate power supplies, the connecter on each power supply usually will have a pin in the connector terminal for sync. If the strobes are to be synched, these pins will be connected between power supplies.

That would be the only way to ensure synching I assume, unless each module had a GPS receiver for timing... which out of interest is done on some sets of high towers where the strobes are synched (GPS modules are less than $50 for this application)!

Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlinerwessel From United States of America, joined Jan 2007, 2416 posts, RR: 2
Reply 9, posted (3 years 8 months 2 days 10 hours ago) and read 3251 times:
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Quoting bond007 (Reply 8):
That would be the only way to ensure synching I assume, unless each module had a GPS receiver for timing... which out of interest is done on some sets of high towers where the strobes are synched (GPS modules are less than $50 for this application)!

Well, it could be anything to keep the timebases synchronized, so long as the relevant items all use the same reference. You could even slave all the clocks to the phases on the AC busses (which is why your clock radio never drifts off the right time).


User currently offlinebond007 From United States of America, joined Mar 2005, 5455 posts, RR: 8
Reply 10, posted (3 years 8 months 1 day 22 hours ago) and read 3173 times:

Quoting rwessel (Reply 9):
Well, it could be anything to keep the timebases synchronized, so long as the relevant items all use the same reference. You could even slave all the clocks to the phases on the AC busses (which is why your clock radio never drifts off the right time).

Yes, very true, but the 'problem' is less with the timing between successive flashes, but more with synchronizing them ... i.e. they can all be flashing at 1 second intervals, but not synchronized. They may start at different times due to delays in the switching of the power supply, the individual module etc. Of course,if your reference interval is the same as the flash interval, this isn't an issue.

Anyway, I feeling somewhat of a geek for even joining this discussion  

Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
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