Cockpit

* User Profile

Welcome, Guest. Please login or register.

Login with username, password and session length

Who's Online

  • *Users: 0
  • *Guests: 25
  • *Total: 25

Author Topic: Interfacing real b737 Yaw demper switch.  (Read 595 times)

Offline Ethanoost

  • Forum GURU
  • *
  • Posts: 26
  • Karma: +0/-0
  • Aviation Enthusiast
  • First Name: Ethan
  • Home Location: Perth, Australia
Interfacing real b737 Yaw demper switch.
« on: May 08, 2017, 05:00:41 AM »
Any advice please. I'm interfacing a real Boeing yaw demper switch in the overhead. It's an on (hold) off type of toggle switch held in place by some kind of mechanism. When a small current is supplied, the switch hold mechanism release and the switch flick back to off. Interfacing it with prosim via a relay is easy.
Here is the issue... there are only two terminals on the switch. The switch uses the same two terminals for the switch and release.. so when the switch is on, the terminals are connected (like any switch). Power should now be supplied through the same terminals for the release to off to occur. See pictures.

How do I interface both a power through a relay and an input signal through the same wires without frying my input card?

Any ideas would be appreciated.

Ethan

Sent from my SM-G930F using Tapatalk


Offline mickc

  • Forum GURU
  • *
  • Posts: 415
  • Karma: +0/-0
  • Aviation Enthusiast
  • First Name: Mick
  • Home Location: VIC, AU
Re: Interfacing real b737 Yaw demper switch.
« Reply #1 on: May 08, 2017, 05:20:01 AM »
Short answer, you can't.  That switch is a switch / circuit breaker combo.  the only way to trip it off is to exceed the current rating of 750mA.

The proper YD switches use a magnetic solenoid, which energized to hold the switch in the on position, otherwise it springs back to off.
« Last Edit: May 08, 2017, 05:33:52 AM by mickc »

Offline mickc

  • Forum GURU
  • *
  • Posts: 415
  • Karma: +0/-0
  • Aviation Enthusiast
  • First Name: Mick
  • Home Location: VIC, AU
Re: Interfacing real b737 Yaw demper switch.
« Reply #2 on: May 08, 2017, 05:45:27 AM »
Well actually you could do it by using 2 relays, one to switch on when the Y/D switch is on, which you connect to your I/O card, and one to apply a fake load to the load side of the breaker, triggered by the Prosim function.

This will isolate your IO card from any spikes from overloading the breaker, and you should be able to get say a 1.5A load by using some resisitors.

Its a dirty way to do it, and there will be a delay in the switch tripping as those breakers have built-in trip delays. These were custom built and the part numbers dont match up with the standard ratings in the datasheet (attached)
« Last Edit: May 08, 2017, 05:46:13 AM by mickc »

Offline Ethanoost

  • Forum GURU
  • *
  • Posts: 26
  • Karma: +0/-0
  • Aviation Enthusiast
  • First Name: Ethan
  • Home Location: Perth, Australia
Interfacing real b737 Yaw demper switch.
« Reply #3 on: May 08, 2017, 07:30:07 AM »
Thanks for the quick reply. Two relays will work. I just need to figure out how to get a small enough load so the switch can trigger the relay without tripping the switch. And then a high load to trip the switch.

Sent from my SM-G930F using Tapatalk


Offline mickc

  • Forum GURU
  • *
  • Posts: 415
  • Karma: +0/-0
  • Aviation Enthusiast
  • First Name: Mick
  • Home Location: VIC, AU
Re: Interfacing real b737 Yaw demper switch.
« Reply #4 on: May 08, 2017, 07:49:31 AM »
Most small 12v relays have a coil current under 100mA so the relay should not cause the switch to trip.

For the "tripping" load, an ideal load would be one of those resistors they use for when you change to LED indicator bulbs on a car.  They provide a 21W load so the flasher operates at the correct speed.  That would work out to a 1.75A load at 12v.

like this one http://www.supercheapauto.com.au/Product/NARVA-LED-Load-Resistor-12-Volt-21-Watt/287170
« Last Edit: May 08, 2017, 08:01:54 AM by mickc »

Offline Ethanoost

  • Forum GURU
  • *
  • Posts: 26
  • Karma: +0/-0
  • Aviation Enthusiast
  • First Name: Ethan
  • Home Location: Perth, Australia
Interfacing real b737 Yaw demper switch.
« Reply #5 on: May 08, 2017, 07:58:56 AM »
Gee thanks. I'll let you know how it goes..

Sent from my SM-G930F using Tapatalk


 

COUNTDOWN TO WF2018


WORLDFLIGHT TEAM USA

Will Depart in...

Recent Posts

Flyengravity order process
by Skysurfer170
[Today at 09:06:28 AM]
FDS-O2 Panels For Sale!!! Realiable Realistic Panels!!!
by KyleH
[Today at 07:01:13 AM]
Opencockpit Indicator Boxes (in US?)
by Nolatron
[November 21, 2017, 05:14:26 PM]
A320 of Fcoq
by Fcoq
[November 21, 2017, 03:00:10 PM]
Simkit flaps
by jackpilot
[November 21, 2017, 02:19:35 PM]
Ok to use only 2 of 4 fastners on crosstube bearing.
by kurt-olsson
[November 21, 2017, 07:57:19 AM]
Worldflight 2017 Conclusion
by Trevor Hale
[November 21, 2017, 07:16:44 AM]
Wooden overhead frame
by Jimmerrelie
[November 20, 2017, 08:49:22 PM]
737-800 Arduino X-Plane Build
by kurt-olsson
[November 20, 2017, 04:07:23 PM]
Another 737 builder :)
by kurt-olsson
[November 19, 2017, 09:08:20 AM]
Home Built Full B737-200 Sim for Sale - Richmond, BC Canada
by Bob Reed
[November 17, 2017, 10:03:12 PM]
Down memory lane - What was the first home cockpit SIM you saw?
by RayS
[November 17, 2017, 02:59:17 PM]
New supplier for your sim
by Fcoq
[November 17, 2017, 02:44:35 PM]
Oh Boy!!
by Bob Reed
[November 17, 2017, 01:37:54 PM]
FDS Shell Black or Raw Aluminum
by bernard S
[November 16, 2017, 06:15:12 PM]
B737 Startswitches
by archen
[November 16, 2017, 12:17:22 PM]
Worldflight Perth Crew news
by Trevor Hale
[November 16, 2017, 07:21:04 AM]
Jorge from NAVCOM
by Caflyt
[November 15, 2017, 04:50:25 PM]
Wanted 5inch screen
by fsaviator
[November 14, 2017, 08:41:16 PM]
737 FWD Overhead Switch Diagram
by MistyBlue
[November 13, 2017, 10:16:15 AM]
Sim out of the hangar
by Fcoq
[November 13, 2017, 10:05:13 AM]
Question for those that have converted real TQs
by mickc
[November 12, 2017, 02:47:54 PM]
Hey - PFD/ECAMS TFT
by BGStudios
[November 12, 2017, 01:22:55 PM]
Camera setup?
by Trevor Hale
[November 12, 2017, 07:48:26 AM]
Sim Progress (BAe146)
by Erj145sim
[November 11, 2017, 08:28:20 PM]
Where to order custom metal rod with predrilled holes.
by bernard S
[November 11, 2017, 11:48:38 AM]
737NG Single Seat Trainer "Starter Kit" :-)
by Captbrian
[November 10, 2017, 08:30:12 PM]
B737 DIY Gauges servo gears ??
by mickc
[November 10, 2017, 07:52:07 PM]
Delta 209
by blueskydriver
[November 10, 2017, 07:06:30 PM]
WorldFlightUSA - UAL 1120 Schedule
by Trevor Hale
[November 10, 2017, 03:53:00 PM]