Levers: Analogue Vs Digital

[tomcat78]

Hi everyone,

Ive been gathering interface ideas from http://www.737ngproject.be . Particularly the throttle unit. Wondering why micro-switches where used for the flaps and trim, instead of analogue axis?
From what i can gather, a clothes peg has been utilized in such a way that it only activates a switch when the lever is traveling one direction, giving the other switch (which activates in both directions), a different output. Thus, flight sim knows what direction the lever is traveling in.
Very clever, but seems unnecessary, when you can do the same with a potentiometer.
I see that potentiometers have been used for the spoiler, and throttle.

Am i correct in my understanding of the switch system, at the before-mentioned web site?

Do micro switches offer some advantage over a simple axis?

Regards

Tomcat

[tomcat78]

Well i will be lame and answer my own question.
Trim cant be a pot because you need "infinate spin" on the wheel.
So digital input for the trim(incremental trim up/down). Either in the form of a micro-switch system, or rotary pulse switch (mouse scroll wheel)
The flap lever can be either be a multi switch (a micro-switch at every increment), or potentiometer. I guess the decision there would lie in what interface you have.
goodnight

[AK Mongo]

Well i will be lame and answer my own question.
Trim cant be a pot because you need "infinate spin" on the wheel.
So digital input for the trim(incremental trim up/down). Either in the form of a micro-switch system, or rotary pulse switch (mouse scroll wheel)
The flap lever can be either be a multi switch (a micro-switch at every increment), or potentiometer. I guess the decision there would lie in what interface you have.
goodnight

Sorry I could not help with you original question. Is it the 737 that needs infinite spin? Most aircraft trim have physical limits that stop them, and as such are perfectly suited for pots. Many people use either multi-turn pots or gearing to mechanically reduce the arc.

It looked like the clothes pin was to create a mechanical encoder, but my Belgian or French is bad, and I could not figure out what the true intent of that was, or why they did not just use a rotary encoder.

Everything else was awe inspiring though!

Reid

[tomcat78]

Sorry I could not help with you original question. Is it the 737 that needs infinite spin? Most aircraft trim have physical limits that stop them, and as such are perfectly suited for pots.

I was under the impression they did, but im new to this, and probably wrong
"google translate" helped me out a bit. I think his trim works using 2 micro switches.
One of them is pushed when the wheel is turned (both directions),
and the other is pushed (by the clothes peg) only when the wheel is spun in one direction, giving the first switch a different output.
If i am right, i would love to know the wiring diagram, i mean both switches must be connected to each other some how.
So maybe there are "stops" to his trim wheel. That would explain the use of the bike chain.

Regards

Tomcat

[MrProach]

i would love to know the wiring diagram

That would explain the use of the bike chain.

Bike chain links wheels on both sides via off-centre rotating shaft.