AUDIO ALERT WIRING

ZK-LCM

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Folks,

My installation consists of a D-100 EFIS, D-120 EMS, & Autopilot which includes an AP-74. One ICOM Comms VHF radio. Day VFR Operations.
The wiring instructions for Audio alerts, (To an intercom), require the audio signal to connect to the Intercom via a 10kohm potentiometer.

My question is. Do I need to connect the audio output from each of these 3 devices through their own potentiometer, or may I put them all through one pot?

Thanks in advance.
Graham
 

Rhino

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It normally only goes on the audio output of the AP74. But if you have an HS34, it goes only on that audio output. Typically this is something you only adjust once, which is why Dynon says it does not need to be pilot-accessible. However, although Dynon does not recommend it, you can also connect the alert audio output from the EFIS and EMS in parallel as a failover capability in the event the AP74 or HS34 fails. If you do that, it's entirely up to you if you use one pot to control all alert audio outputs, or individual pots to control them separately.. If you decide to add in the failover audio, you could start out with just a single pot. If you notice an unacceptable difference in the audio alert volume from the EFIS or EMS when the AP74 or HS34 are turned off, you can add pots to those audio outputs too. Since such a failure is unlikely, and since a difference in volume would likely be the least of your worries in that case, I'd just opt for one pot. If you use individual pots, those too would only need to be adjusted once, and would not need to be pilot-accessible
 

jakej

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Sounds like a job for the FDS AP-60 ? I've always used a 'pot' on a single audio output, remote mounted & cable tied to the loom, works well, YMMV.
 

Rhino

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You could use a mixer I suppose, but there's probably not much point since there shouldn't be any other audio present unless the AP74 or HS34 fails. In the event that happens, the audio alerts coming from the EFIS and EMS are not identical like alerts coming from the AP74 or HS34 are, so the distortion shouldn't be that much of a problem. I'd do what you've always done, just use one pot. But the world is full of builders who don't want to do what others have done.
 

ZK-LCM

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Thanks everybody.
Interestingly Dynon advise me that I must use only one pot and put only one audio alert input into it.
So tomorrow I shall try just my EFIS audio output into the pot.
Of course, the components all talk to each other thru the DSAB.
 

ZK-LCM

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Ahh well, progress at last today, after frustratingly trying every combo of outputs & wiring.

It transpires that I had to delve into my ICOM IC-A210 Comms menus to setup the auxiliary inputs. You can turn them off (why would you?), ON, & adjust input volume.
So now I get audio alerts.

There are still a couple of funnyocities that I haven't figured out yet, but 90% there.

So plse Dyson put a sentence in your Manual warning that when using aux inputs to a Comms unit the installer might need to go thru the comms radio setup menu for their aux inputs.

Oh, and the other question is. Seeing as I can adjust the aux input vol within the ICOM do I still need the 10kohm potentiometer as specified by Dynon?
 

Rhino

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Be aware that the aux input on the A210 is muted whenever squelch is broken, so you may not hear alert audio when you need to. Other people using that input have reported background noise and low volume levels. But if you do use the A210 aux input instead of connection to an intercom, no, you shouldn't need the pot.
 

ZK-LCM

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Well, most of the audio alerts work OK & the Test functions all work.

BUT

My AOA voice and tone warnings all come on, even when I set a Min speed, and my AOA symbol shows a solid Red alert.

That in itself is strange, but what follows is even stranger.

When I turn on Pitot Heat my warnings and red symbology all go away?????

Better do some more troubleshooting.............
 

GKC Aviation

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This is a pretty fascinating defect!
I will be following to see what you find here.

AoA is serial data from the ADAHRS unit. Maybe try a Zero pressure IAS/AoA calibration as a start.
This won't affect your AoA calibration data and is very easy.

Pitot heats only connection to the SkyView is a contact from the controller to the EMS for indication, should not affect anything to do with your serial data.
I would lean towards a voltage problem, as the pitot heat draws a bit of power, probably more than anything else in the SkyView system.

Keep us updated.
 

ZK-LCM

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I do NOT have a Skyview.
My installation consists of a D100, D120, AP74 and a Dynon Heated Pitot/AOA system.
So the AOA data comes from the Dynon Pitot/AOA.
 

Rhino

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There is no data from the AOA to the D100. It's just tubing to provide air pressure to the D100, and the D100 does all the data computations internally. But no matter what system you have, pitot heat is a separate connection, so GKC's point that it shouldn't directly affect AOA data calculation is correct. This just makes the problem even more fascinating.
 

ZK-LCM

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I suspect my problem is due to my Pitot Heat warning light being wired into my D120 EMS, which is permitted by the instn Manual.

And of course, all of the Dynon items talk to each other via the ADSB.

I shall ask Dynon directly.
 

christoffer

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Nov 27, 2020
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Hi,

I have a D180 that is already connected to intercom and now adding a H34 and AP74. Will I get the audio through the D180 (from DSAB) and I dont have to connect the HS34 audio output?
 

Rhino

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You can still get EFIS and EMS alerts from the EFIS alone if you want. Just be aware that you may not get other audio, such as marker tones, that the HS34 receives from other sources.
 

christoffer

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So the best idea might be to move the audio out cable from D180 to HS34 or have cables coming from both to the audio panel?
 

Rhino

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Just the HS34. If you have both the EFIS and HS34 connected together, there would likely be audio distortion. Be aware there are two audio outputs from the D180. One is EFIS alerts on pin 18 of the D25 connector, and the other is EMS alerts on pin 31 of the D37 connector. They would both be replaced by the single output from the HS34.
 
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ZK-LCM

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Hopefully the installation is now completed. Though we haven't flown yet.

Here is what I ended up doing.

1. I did not put my aural warnings, (from the EFIS only), thru a potentiometer, instead I adjusted the ICOM aux input volume internally.

2. On Dynon's recommendation I disconnected my Pitot Heat wiring from the EMS and wired it direct to a warning light per the manual.
I suspect an EMS software "bug" caused my aural warning issues.

3. I took my 12 V for the warning light from the "downstream" terminal of the Pitot Heat switch.
By doing this the warning light is only ever on if there is a fault, and the Pitot Heat is selected.

Regards & thanks.
Graham
 

Rhino

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Sounds good, Graham. Let us know how the flight test goes.
 
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