Newbie Question on Servos

[Skyfog]

When the 5-in-1 initializes (and assuming trims and sub-trims are all 0) do the servos always return to the exact mid-point of their travel? How do they know?
Thanks,
Skyfog

[Imzzaudae]

Hello. Welcome to Helifreak.

The servo has 3 electrical contacts.
2 are power Plus and ground that power the servo motor.

The other is a variable resister that changes a given voltage as it moves up and down the contact. Say it's 3VDC at one end and 3.5 at the other end. This voltage is fed into a capacitor that charges and discharges at a different rate as the voltage changes. This happens thousands of times a second.

When the capacitor discharges, it creates a pulse that can be counted.
buy a simple computer. So the position of the brush can be determined but the number of capacitor discharges per second.

Think 0 = low end, 50 middle position, 100 = high end
Now apply this.
If A is less than or = to 50 do this
If A is greater than or = to 50 do this

It's a simple timing circuit that allows a computer to determine position
and with some simple programing lets the computer make adjustments via some very cool programing logic.

Look up Timex Sinclare 1000.
This was my first computer. It operated on on a language called Basic.
Back before Dos operating system or Windows where invented. I used to program it to play simple advertising to run on televisions at my dads TV store.

Study Basic a bit, It will open your eyes to many wonderful ways of looking at things. Same as how joysticks work. Very cool stuff.

At that time this is what a video game looked like!

Atari 2600 Breakout gameplay (2 min 50 sec)

Hope this helps.
Ron

[SplashN'Crash]

Originally Posted by Skyfog

When the 5-in-1 initializes (and assuming trims and sub-trims are all 0) do the servos always return to the exact mid-point of their travel? How do they know?
Thanks,
Skyfog

The exact mid point, no. Pretty close though. They travel to where the transmitter was set (mid travel on the cylcics) when bound.

Ron, what were you thinking? Did you paste the wrong reply?

[Imzzaudae]

Hi Garry.
After reading his question again, I would still answer his question how do they know the same. To me the question is how do the servos know where the center point is. This is how they determine position. Then the servo starting point can then be controlled buy the transmitter.

[Skyfog]

Ron and Garry, thanks for your replies.
I figured there must be a potentiometer built into the servo, but I haven't (yet) crashed my heli bad enough to go in that deep to look.
Ron, yes, I'm familiar with BASIC and a number other computer languages, having spent 31 years at Ford in computer systems. Am presently retired and playing around with PIC microcontrollers.
And Garry, do I understand correctly that if I bind with the cyclic held off-center, that will be the new "neutral" for the servos? That will be an interesting experiment to perform.
Thanks again,
Skyfog

[Imzzaudae]

Skyfrog
During the winter when I cannot fly helicopters, I am also into Microsoft Flight Simulator! Building a home cockpit around the FSX 737 gauge pack.

The cockpit measured 10' long 7' wide and 5' high.
The outside image is projected.
Inside. The cockpit is all LCD Monitors behind the instrument panel
via FS Panel Studio.

After a considerable amount of time hacking keyboards and joysticks,
I ended up using a Hagstrom Electronics KE72 for switching and rotary controllers from Digi-key, built the yolks and throttle quadrant myself.

Home made AP and Radio Stack as I was wiring it.


The sim has taken me 10 years to draft and construct.
I'm CVA 300 on Vatsim if your ever flying on Vatsim.

This is not my cockpit but it is very close to what I have built.

Approaching Innsbruck , 737- home made cockpit (11 min 7 sec)

I fly the simulator full IFR, real time weather conditions all over the world usually with a copilot as flying is a handful and a spare set of hands is always nice to handle radios when going into busy airports.

Cost. several k but it's a blast to fly and my other half hates it.
That alone makes it worth all the trouble!

[Skyfog]

Hi Ron,,, That's very impressive! I'm sure it's a blast to fly. Good luck with it.

-Skyfog