Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 2 of 2 FirstFirst 12
Results 11 to 12 of 12

Thread: LED light interference

  1. #11
    Senior Member HighWing's Avatar
    Join Date
    May 2009
    Location
    Goodyear, AZ
    Posts
    1,743

    Default Re: LED light interference

    This is what I have learned about LEDs. They are powered by a power supply that monitors amperage rather than volts. If you have a LED listed at 3 volts and use a resistor to reduce the 12 volts in our system to 3 volts it will light the LED. However during the engine run when the charging system has raised the voltage to close to 14 volts, it will over power the LED. Or conversely if the battery is not producing 12 volts the LED will be under-powered. Both these situations will result in a different light output. The "Powers that Be" have determined that LEDs are more efficient with constant current. The circuitry that monitors and adjusts current appear to be very noisy as it apparently produces frequencies in our RF band that we can hear during radio reception.

    All the LEDs will produce light using a resistor with no noise, but the light output will not be a consistent brightness. I would expect that the light arrays produced specifically for aviation use have filtering systems built into the power supply that eliminates the high frequency noise we hear in our headsets. That is likely why they are priced as they are.
    Lowell Fitt
    Goodyear, AZ


    My You Tube Channel

  2. #12
    Senior Member
    Join Date
    Oct 2016
    Location
    Western Australian
    Posts
    218

    Default Re: LED light interference

    I will be fitting these, eventually, to my aircraft. They are very, very popular on the Eurfox (A220) and I have not heard one mention of interference:

    Whelen Strobes

    Easy install and no boxes to build up enough ummphh for a flash.

    I was originally going to use a 3 core shielded cable (power, ground, synch) but following the advice below (from AeroLED) I'm now going to use 2 core, with the shield being used as a ground return. I wasn't even considering using the shield for this purpose but it seems the LED engineer-types reckon it's a good idea and helps eliminate noise:


    How To Minimize Strobe Noise

    LED strobes operate differently than legacy Xenon strobes.

    Legacy Xenon strobes use a flash capacitor that charges up continuously between flashes, pulling a steady amount of current, then dump the charge to the Xenon tube in a single burst.

    LED strobes pull their current while the strobes are lit, and pull nearly zero current between flashes.

    As a result, the way that the LED strobes are wired will make a huge difference in whether or not audio frequency noise gets into your intercom. Because the current pulses to LED strobes flow in a loop with the outgoing current flowing in the outbound power wire, and the return current flowing in the ground path, there is the potential for the wiring to create time varying magnetic fields that can couple into adjacent wires such as headset jack cables, or even your antenna coax cable.

    To prevent this, it is highly recommended that you follow the following wiring recommendations:

    1. Use shielded wire, AeroLEDs has 3 conductor 20 gauge shielded wire available for this purpose.

    2. Use the shield as the ground return. When the ground current flows immediately adjacent to the power wire, the magnetic field produced by the power wire current is canceled out by the current flowing in the shield. The ground current prefers to stay in the shield rather than flow through structure because generating a magnetic field takes energy, and the current wants to follow the path that takes the least effort because the fields cancel out (called the path of least inductance).

    3. Bring the shielded wire run all the way to the panel, where the power wire can go to the switch, and the shield ground can be run to the behind the panel grounding block. If you need to break the wire run at the wing root with a connector or terminal block, that is OK as long as you resume the shielded wire in the fuselage and connect the shield grounds through the interconnect.

    4. As much as possible, keep some separation between the strobe wires and sensitive cables such as intercom audio cables, headset jack cables, or antenna coax for the radios.


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •