VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   Glass Cockpit (https://vansairforce.net/community/forumdisplay.php?f=35)
-   -   Gad27 Voltage Stabilizer (https://vansairforce.net/community/showthread.php?t=149646)

g3xpert 06-29-2018 08:40 AM

Quote:

Originally Posted by tgmillso (Post 1270157)
Hi All,

I just spoke with the Garmin tech support line, and they said to check the resistance between the two ground pins on the GDU460 (also the GEA24 as this as two ground pins also). If I have continuity, or near zero ohms resistance, which they suspect will be the case, then the two pins are joined internally and subsequently I would not need the second ground wire. If this is not the case, then there is some type of switching that goes on when the voltage drops, and thus I will need to connect the second ground wire for the keep alive function to work. Fingers crossed it's option one.
Tom.

Hello Tom,

Ground pins 15,16 on the GDU 460 (and pins 6,9 on the GEA 24) are connected together to the same ground inside the unit.

When you have dual power source inputs to the display, it is ideal to have dual ground wires so in the unlikely loss of one of the ground wires you don't lose both power sources, but the display will work just fine with a single ground wire as long as the power ground is common to both power sources.

Thanks,
Steve

tgmillso 06-29-2018 04:29 PM

Thanks Steve. Excellent news.

Tom.

BoilermakerRV 08-24-2018 08:56 AM

Keep Alive Setup
 
Does the GAD 27 keep alive need to be powered from a separate battery? I'm struggling to understand how it can maintain voltage if the entire battery system is being pulled down by the starter. Big capacitors?

g3xpert 08-24-2018 03:41 PM

Quote:

Originally Posted by BoilermakerRV (Post 1283186)
Does the GAD 27 keep alive need to be powered from a separate battery? I'm struggling to understand how it can maintain voltage if the entire battery system is being pulled down by the starter. Big capacitors?

Hello Michael,

No, the GAD 27 does not need to be powered from a separate battery.

The GAD 27 is designed to be connected to the same primary battery bus that is being used to start the engine. Even though the act of starting the engine may temporarily draw the bus voltage down below where some devices can continue to operate, the GAD 27 will condition that power and provide 12Vdc at up to 3.5A to several devices which you want to keep in operation through engine start.

For example, a common installation would be to wire primary power to power input 1 on PFD1, GSU 25, GEA 24, and the GAD 27. Next, the keep alive power output from the GAD 27 may be wired to the power 2 inputs on the PFD1 primary display, GSU 25 ADAHRS, and GEA 24 engine monitor.

When you turn on your primary bus, the PFD, ADAHRS, and engine monitor can come up running, and then when you start your engine, these devices will continue to run (automatically switch to using power input 2) when the voltage dips on power input 1.

This allows your PFD to stay running with engine information, your ADAHRS to either continue aligning or stay aligned, and allows your engine gauges to all operate before, during, and after engine start.

Best of all, it does all of this without a battery, so you don't have the long term maintenance requirements associated with a battery.

Let us know if you have additional questions.

Thanks,
Steve

BoilermakerRV 08-30-2018 12:25 PM

Endurance Bus
 
I'm organizing my endurance and main busses, and a thought occurred to me. Given the following setup...
PFD1, GEA and GSU A/C Power 1 <--> Main Bus
GAD 27 A/C Power 1 <--> Endurance Bus
PFD1, GEA and GSU A/C Power 2 <--> GAD 27 Keep Alive
If I kill power to the Main and run only on the Endurance, will the GAD 27 continue powering the devices connected to the Keep Alive. If it works this way, it would basically be an extension of the endurance bus.

Quote:

Originally Posted by g3xpert (Post 1283320)
Let us know if you have additional questions

I really appreciate the continuing support of the g3xpert team!

g3xpert 08-30-2018 01:41 PM

Quote:

Originally Posted by BoilermakerRV (Post 1284709)
I'm organizing my endurance and main busses, and a thought occurred to me. Given the following setup...
PFD1, GEA and GSU A/C Power 1 <--> Main Bus
GAD 27 A/C Power 1 <--> Endurance Bus
PFD1, GEA and GSU A/C Power 2 <--> GAD 27 Keep Alive
If I kill power to the Main and run only on the Endurance, will the GAD 27 continue powering the devices connected to the Keep Alive. If it works this way, it would basically be an extension of the endurance bus.

I really appreciate the continuing support of the g3xpert team!

Hello Michael,

You are very welcome.

Yes, anytime you apply power to the GAD 27 Keep Alive power input on pin 1 of terminal block TB273, the devices connected to pin 2 on TB273 will receive conditioned power (all the time, not just during engine start).

The computer side of the GAD 27 even receives diode isolated conditioned power internally from the Keep Alive output, so the GAD 27 also protects itself from reset during engine start by using the conditioned power it sources.

Thanks,
Steve


All times are GMT -6. The time now is 03:38 AM.