AVSIG: Strobing Runway Lights wwswsigarch.jpg (7236 bytes)

✈ . . . . . . ✈ . . . . . ✈ . . . . ✈ . . . ✈ . . ✈ . ✈ . . ✈ . . . ✈ . . . . ✈ . . . . . ✈ . . . . . . Touch-and-Go to our Live Forum (This is a Read-only Archive of the 2004-2017 AVSIG Forum)


AVSIG Discussion Sections >> Training & Proficiency

Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Strobing Runway Lights
      12/15/17 06:20 PM

Quote:

I would speculate that the Pulse Width Modulation (PWM) dimming system of the LED runway lights was phasing with my propeller, causing the observed effect.




Maybe. Doing the math, 3 blades x 2400 Rev/min x 1/60 min/sec = 120 cycles/sec. Exactly what you'd expect for a light powered by the 60Hz mains.

Yes, standard dimmers use a type of PWM for dimming, but I don't think that's the real issue. The problem is the LEDs "flicker" in time to the AC mains that the old incandescent (being a heat-based device) couldn't.

The problem here might be retrofitting dimable LED bulbs on a conventional circuit. I haven't looked to see how dimable 120V LED bulbs work, but I'd imagine they have to be responsive to the "PWM"/dimming of the conventional system to function properly. Simply rectifying and smoothing the incoming voltage is going to result in a bulb with really strange dimming characteristics. (Normal brightness until below 50% and then rapid dimming as the cycle drops.) As a result, a strong 120Hz strobe is quite likely.

An LED system designed from the ground up to be LED may run at a higher PWM speed and not cause that problem.

Post Extras Print Post   Remind Me!     Notify Moderator


Entire topic
Subject Posted by Posted on
* Strobing Runway Lights Scott Dyer [HPN/NY] 12/15/17 04:25 PM
. * * Re: Strobing Runway Lights Terry Carraway   12/18/17 09:27 AM
. * * Re: Strobing Runway Lights Russell Holton   12/18/17 12:54 PM
. * * Re: Strobing Runway Lights Ralph Jones   12/15/17 06:25 PM
. * * Re: Strobing Runway Lights Jeff Hartmann CIC   12/15/17 06:23 PM
. * * Re: Strobing Runway Lights Scott Dunham (RDU)   12/15/17 08:27 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/15/17 10:15 PM
. * * Re: Strobing Runway Lights Russell Holton   12/15/17 11:12 PM
. * * Strobing Runway Lights Bob Dubner   12/16/17 12:16 PM
. * * Re: Strobing Runway Lights Russell Holton   12/18/17 06:08 PM
. * * Re: Strobing Runway Lights Gil Buettner [KAUW]   12/18/17 05:39 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/19/17 01:54 PM
. * * Re: Strobing Runway Lights Russell Holton   12/19/17 02:31 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/19/17 08:04 PM
. * * Re: Strobing Runway Lights Russell Holton   12/19/17 08:34 PM
. * * Strobing Runway Lights Bob Dubner   12/21/17 01:36 AM
. * * Re: Strobing Runway Lights Terry Carraway   12/23/17 10:27 PM
. * * Re: Strobing Runway Lights Russell Holton   12/24/17 06:54 PM
. * * Re: Strobing Runway Lights John O'Shaughnessy [FCM]   12/25/17 10:02 AM
. * * Re: Strobing Runway Lights Russell Holton   12/25/17 02:06 PM
. * * Re: Strobing Runway Lights Tom Charlton   12/25/17 12:35 PM
. * * Re: Strobing Runway Lights Terry Carraway   12/25/17 07:20 AM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/19/17 09:48 PM
. * * Re: Strobing Runway Lights Russell Holton   12/20/17 04:28 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/20/17 05:29 PM
. * * Re: Strobing Runway Lights Nancy Zeitlin [HPN]   12/20/17 11:47 AM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/20/17 04:07 PM
. * * Strobing Runway Lights Ward Miller POU-NY   12/20/17 05:40 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/20/17 09:17 PM
. * * Re: Strobing Runway Lights John O'Shaughnessy [FCM]   12/20/17 04:24 PM
. * * Re: Strobing Runway Lights Russell Holton   12/20/17 04:37 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/20/17 05:33 PM
. * * Re: Strobing Runway Lights Russell Holton   12/20/17 06:28 PM
. * * Re: Strobing Runway Lights Randy Sohn   12/15/17 08:57 PM
. * * Re: Strobing Runway Lights Russell Holton   12/15/17 06:20 PM
. * * Strobing Runway Lights Ray Tackett   12/15/17 05:19 PM
. * * Re: Strobing Runway Lights Scott Dyer [HPN/NY]   12/15/17 06:32 PM
. * * Strobing Runway Lights Ray Tackett   12/15/17 08:13 PM

Extra information
0 registered and 61 anonymous users are browsing this forum.

Moderator:  Mike Overly 



Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled

Rating:
Thread views: 6493

Rate this thread

Jump to

Contact Us AVSIG

Powered by UBB.threads™ 6.5.5

Logout   Main Index    AVSIG Aviation Forum