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  #1  
Old 01-02-2020, 07:32 PM
N546RV's Avatar
N546RV N546RV is offline
 
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Default Is this a reasonable way to wire up my landing/taxi/wigwag lights?

The struggle to nail down my electrical system continues; let's talk about how I want to do my landing and taxi lights.

The light units will be Flyleds combo units, one in each leading edge. For those unfamiliar, each unit has four projectors, one of which can be separately switched and aimed to act as a taxi light. Since I'm building a TW aircraft, I intend to use that functionality. I also want to have wigwag functionality for these lights, and I intend to use the Flyleds wigwag module to do this. What I want is to have two switches: one three-way switch with OFF/TAXI/BOTH positions, and one two-way switch to enable wig-wag.

The first source of interest here is that the wigwag module only has single power outputs, one for the right wing and one for the left. I want the wig-wag function to power both the landing and taxi units, which means at that point the landing and taxi circuits must be tied together - which means I lose the ability to apply power only to one of those circuits when I want the TAXI/BOTH switch on.

The second is sort of the other side of that coin; if I want to have a single switch for OFF/TAXI/BOTH, then the power outputs there for landing and taxi are electrically tied together, which prevents the wigwag module from being able to only apply power to one wing.

Basically, the issue is that every circuit can backfeed every other one.

Now, I'm a bit naive when it comes to electronics, but offhand this seems like a problem that can be solved with diodes - strategically placed diodes prevent any leg of the circuit from backfeeding any other one. The only practical problem I see is that I'll incur a voltage drop at all times to these circuits. But some annoying part of my brain wants to think that this isn't the way this should be done.

So what I'm asking is: is this a reasonable approach, or not?

Example schematic:
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  #2  
Old 01-02-2020, 07:43 PM
rocketman1988 rocketman1988 is offline
 
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Default flyleds

Have you looked at the wigwag module documentation? They have numerous wiring scenarios...
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  #3  
Old 01-02-2020, 08:03 PM
Canadian_JOY Canadian_JOY is offline
 
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Might I suggest you consider a paradigm shift?

When in wig-wag mode you will most likely be airborne or in the runway environment where wig-wag is needed for anti-collision purposes.

When you are taxiing you will be doing just that, hence the taxi light function will be in play.

I would suggest that you change your switching concept such that S1 controls the landing lights in OFF-Wig-Wag-ON modes, and the second switch, S2 is a simple Taxi Light on-off switch.

In a typical flight scenario, you would start up and taxi out with S2 taxi lights turned ON. When taking the runway environment you would leave S2 ON, turn S1 to the ON position, taxi into takeoff position and blast off.

Once in the air you would turn off the taxi light via S2 and set the landing lights to wig-wag position with S1.

Before landing you would once again move S1 to the ON position to get full landing lights. After landing turn S1 OFF and S2 taxi lights ON to taxi back to the hangar. Since you are transitioning from flying to landing angle of attack you might switch the taxi lights on while on final so you get a nice smooth transition in lighting as the tail comes down on roll out.

Controlling the taxi lights completely independently gives you light on the pavement when you need it while giving you the option to turn off the big lights so as not to fry the retinas of your fellow pilots on the ground.

Wig-wagging that fourth taxi light module doesn't really buy you anything operationally - the three landing light modules on each wing will be plenty visible when wig-wagged. I'm not sure why you would want to add all that wiring complexity to accomplish something that really doesn't buy you an improvement in your ability to see at night or the ability of others to see your aircraft. KISS is good!
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  #4  
Old 01-02-2020, 10:08 PM
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vlittle vlittle is offline
 
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The FlyLeds lamps need 12.75 Volts to reach maximum brightness and output drops noticeably below 12 volts.

A series diode will add a 0.5 To 0.7 Volt drop, depending on type, thus adding to the minimum voltages required.

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  #5  
Old 01-03-2020, 05:45 AM
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Paul from Flyleds Paul from Flyleds is offline
 
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All of what Canadian Joy said. (Thanks Mark!)
Just wigwag the landing lights. You will be seen coming for miles with these alone.

You can use two standard ON-OFF switches if you like, one for taxi and one for landing/wigwag with the Flyleds wigwag module set for "single switch" mode.
Unfortunately you can't use a progressive switch to do off/wigwag/landing without using two external diodes, which is not desirable.
However you could use a DPDT center-off switch as per diagram C instead (wigwag/off/landing)...

[For reference the Flyleds wigwag module effectively has two lossless or ideal diode isolated outputs, which explains how some of the example connection diagrams (eg; diagram D) work without cross-feeding each other.]

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  #6  
Old 01-03-2020, 06:34 AM
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N546RV N546RV is offline
 
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Quote:
Originally Posted by Canadian_JOY View Post
Wig-wagging that fourth taxi light module doesn't really buy you anything operationally - the three landing light modules on each wing will be plenty visible when wig-wagged. I'm not sure why you would want to add all that wiring complexity to accomplish something that really doesn't buy you an improvement in your ability to see at night or the ability of others to see your aircraft. KISS is good!
I think you hit the crux of thing right here. If I may digress a bit: I write software in my day job, and there are times when I look at something I'm working on and it just feels clunky/overcomplicated. Often I can't quite put into words why it is that way, it's just a sort of subconscious feeling.

So I posted this because the more I tried to make that circuit work, the more I was getting that feeling of ambient wrongness. And you've pointed out the one detail I was fixated on that, if discarded, could make it all unnecesary.

I like your suggested shift. The single-switch mode on the module could be another way to solve this problem, but I like the idea of having a physical switch position to indicate what mode I'm in. Granted, if I'm landing at night and in wig wag, it'll be pretty obvious, the inverse case not so much...

It took me a bit of puzzling to figure out how to make the progressive switch work as desired for this case, but I think I have it:



How does that look?

Thank you all for your input!
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  #7  
Old 01-03-2020, 07:30 AM
Northernliving Northernliving is offline
 
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Default Ask Paul

Shoot a note to Paul at FlyLEDs. He was highly responsive to all my wiring questions.
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  #8  
Old 01-03-2020, 07:45 AM
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Paul from Flyleds Paul from Flyleds is offline
 
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Quote:
How does that look?
No good.
The link where you have the words LAND(BOTH) effectively shorts the two outputs of the wigwag module together. Nothing blows up but you don't get the wig or the wag!
This is the point where you would need to insert blocking diodes, but you need to find ones with a low forward voltage drop. I could source something suitable but mounting and wiring them will need work...

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  #9  
Old 01-03-2020, 09:31 AM
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N546RV N546RV is offline
 
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Argh, you're right...that's what I get for drawing schematics on the bus, I guess...
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  #10  
Old 01-04-2020, 06:08 PM
fly3g fly3g is offline
 
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Default Another schematic idea

I am doing a similar FlyLeds Combo installation. The scheme I was looking at to wire was this.

I think it would allow the following lighting states: Off / taxi lights only / landing + taxi / wig wag both landing and taxi / taxi + wig wag landing (not sure why I would use this last state).


Last edited by fly3g : 01-10-2020 at 08:00 AM. Reason: attempt to finagle with image path to make it visible
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