B737 Yaw damper/Anti-ice switches

[sagrada737]

Hello Anders,

VEry cool design.  Your innovation on these sort of details is remarkable.  Again...  I sure enjoy my Start Switches.

Regarding your video on the Yaw Damper Switch...   You indicated that the solenoid get "very hot to the touch".  I'm a bit nervous about that, as once the Overhead is closed up, that solenoid might become even hotter.  Any solution to this heat issue - other than an added fan?

Mike

[archen]

Hello Mike,
Thanks for your comment.

The heat side of things is what I'm testing and have been testing the last week. A solenoid gets quite hot during operation and that is normal.

The solenoid I'm using have a insulation class A which is specified to have a working temperature up to 105 C°. The temperature rise is approx 55 C° during continues use which gives as an ambient temperature of 50 C° before the solenoid exceeds it's specifications. I doubt anyone will have those temperatures in the overhead compartment.

The solution if overheat conditions occur would indeed be a heatsink or fan.

To make sure the solenoid will not get overheated, which can generate smoke and destroy the solenoid, I've added a  thermal resetable fuse which will cut the circuit if the solenoids core exceeds 100 C°. That will save the solenoid and protect it from melting.

Once the solenoid gets colder again the fuse automatically resets.

Still doing tests with this and with different ambient temperatures. That's what takes time but I don't wanna rush into things.


Anders

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[andthiel]

Hej Anders,

Great job again! Tack ska du har!

Please put a pair on the order list for me, too.

Många hälsningar från Tyskland,

Andreas


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[archen]

Regarding the yaw damper I have bad news. I don't feel comfortable with the heat the solenoid is generating so I'm looking at another solution. When I decided not to manufacture the version I showed you guys I was well into these switches so when IRS switches is official I'm going to redesign yaw damper. Sorry, but risking anyone's cockpit due to the overheat problem does not feel good and I would never risk that so this was the only option.

I do have an idea how to achieve the same result (solenoid not kicking the toggle back) without having to power the solenoid at all time.

Anders


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