Servo Power for throttles

[imported_redman]

Hi there,
just a question on powering my servos.
I am hooking up three 815BB servors to power my throttle and speedbrake handles.
I will be wiring the red wires from the servo directly to a power supply, with the black wires going to both power supply and the phidget card (which also gets the white control wire)
I am trying to find a variable power supply as mentioned in the auto-throttle tutorial.
Can anyone confirm that it is a 8 Amp 4.8-6VDC source?
I am having trouble finding something with that many Amps. Will something outputting only 1000mAmps burn out?

thanks
Chris

[mauriceb]

I am trying to find a variable power supply as mentioned in the auto-throttle tutorial.
Can anyone confirm that it is a 8 Amp 4.8-6VDC source?
I am having trouble finding something with that many Amps. Will something outputting only 1000mAmps burn out?

thanks
Chris

8 AMP is way too much for this, but 1000mA (1 A) is likely not enough. I had trouble finding a 6V power supply, so I used 2 X 6V-1.5A power supplies that Phidgets sell for their interface cards and I connected the output wires in parallel together (watch the polarity) so that the output amps add up to 3 Amps. This is more than enough for my 3 servos especially since the speed brake only comes on after landing.

A 5V- 2 to 3A power supply would also work depending on how much friction you have in your throttles. If they are fairly loose, it will work fine (that's what I used during the construction & testing phase of my throttle).

Hope this helps,
Maurice
ps. It does not have to be a variable power supply

[imported_redman]

Thanks Maurice,
Now comes the fun part.
I have a question regarding the implementation of the speed brake lever with a servo.
From your web site you describe having additional circuits to only use the servo when on the ground, and armed.
I am tryng to get my head around what i need to do for this.
Does this mean you do not use FS2phidgets to control this function? How did you program/setup this logic? What additional hardware/wiring was needed? (i am still learning about wiring and components, so a bit of a newbie in this area)

I looked at FS2 and saw there was a speedbrake hanldle variable, but this tracked movement all the time.

Has anyone else implemented a servo on the speedbralke handle?

Thanks
Chris

[mauriceb]

I looked at FS2 and saw there was a speedbrake hanldle variable, but this tracked movement all the time.
Thanks
Chris

Exactly. If you have a potentiometer controlling the speedbrake, that potentiometer is always 'active' in FS? as opposed to the way the throttle behaves in FS?. When the autothrottle is on, FS9 ignores any inputs from the potentiometers that are attached to the throttle handles.

That's why I found you have to disable the spoiler servo when in flight. Otherwise you get conflicting inputs to the servo & I had found that at times, my spoiler handle was going nuts & swinging all over the place. Besides, you cannot move the spoiler handle if the servo is active anyway.

So you have to disable the servo one way or another when in flight, either via software commands (which I don't know how to do with the Phidgets software), or by removing the power to the servo which is fairly easy to do.

The circuit you saw simply disconnects the power to the servo unless the spoilers are armed and the plane touches down. At that point, you are not moving the handle. FS9 is & does that by changing the variable and that same variable makes the servo move the handle to the fully extended position.

After you re-apply the power, FS9 again is in control and retracts the spoilers automatically like in the case of an aborted landing for instance (you don't have time to think about retracting the spoilers manually). Once the spoiler handle is back in the home position, I simply used a switch the disable the power to the servo again.

I'm sure there are probably better & more 'elegant' ways of doing this, but this works for me.

Hope this helps,
Maurice

[imported_redman]

...by removing the power to the servo which is fairly easy to do.
I simply used a switch the disable the power to the servo again.

Hi Maurice,
If I read this correctly, are you using a hard wired switch that you turn on after arming the spoilers, which then will send power to the servo ?

Are you using ps2phidgets to control your servos? With your logic for auto throttles (i.e autothrottle on plus other state) is this done through fs2phidgets or something else?

Like the speedbrke, I can't seem to see anywhere to add logic to the phidget control (i.e. an if/then type of logic).

Thanks again.
Chris

[alandyer]

Gentlemen,

How about I add a software setting to inhibit servo when spoiler is armed ?

i.e. user can choose an fs variable ( or variables ) to use as the inhibiter.
In case of the spoiler,
would the inhibit variable be Spolier Armed ( offset BCC ) ?

Shoot me a PM and we can work a solution.

Regards,
Alan

[mauriceb]

Gentlemen,

How about I add a software setting to inhibit servo when spoiler is armed ?
Regards,
Alan

Hi Alan,

Actually, the reverse should be true. You don't want to inhibit the servo when the spoiler is armed, otherwise it would never deploy after landing. But even if you used the reverse logic and enabled the servo when the spoiler is armed, that would not help either.

From what I have seen, the spoiler armed indicator does not just stay on only when the spoiler handle is in the ARM position, but also after it has deployed after landing and also at other times. It shouldn't but it does at times and I don't understand why.

My experience with the 'arm' offset has been that you can't rely on it except when you arm it before landing. After landing, it behaves erratically (in my experience anyway). That's why I had to find an alternate way to handle the spoilers.

So, thanks a lot for offering a possible solution, but at least in my case, that would not resolve the issues I had with the spoilers. I did manage to design a roundabout way to handle it with some additional logic as you can see in my schematic in the link below if you are interested.

Best regards,
Maurice

[mauriceb]

Chris,
See my comments in red below:

If I read this correctly, are you using a hard wired switch that you turn on after arming the spoilers, which then will send power to the servo ?

No, not at all. The hard wired switch is just to remove power to the spoiler servo; you do not physically actuate the switch...it is actuated by the spoiler handle when the spoiler retracts (see schematic & explanation below)

Are you using ps2phidgets to control your servos? Yes With your logic for auto throttles (i.e autothrottle on plus other state) is this done through fs2phidgets or something else? Combination of Phidgets + my own logic circuits

Like the speedbrke, I can't seem to see anywhere to add logic to the phidget control (i.e. an if/then type of logic). That's why I had to design my own circuits

Regards,
Maurice

[imported_redman]

Maurice / Alan,
I think i am getting there (both mentally and physically!)
I will use fs2phidgets to control movement of throttles, and speedbrake lever.
The ground of the power for these servos will be sent through a 0/16/16 board.
the LevelD 767 has autothrottle status (i.e. 0=OFF, 1=ARMED,3=SPD, 4=N1, 5= FLCH, 9=FAIL, etc), so through FSCONV and SIOC i can write a logical if statement that will write an offset ($8BFF) bit to 1 if the autothrottle status is >1 and <9.
I can set fs2Phidgets to open the 0/16/16 digital output when this is true, thus powering the servos.

Same for the speed brake (i will write a offset to 1, when on the ground, >60kts and level is armed, and will have is reset back to 0 when spoiler is DOWN)

Just have to make sure that the 0/16/16 card can handle the power of the two wired power supplies.

Hope this makes sense / will work. Any comments?

Thanks again

Chris

[mauriceb]

Sorry but I don't really understand what you are doing, so the only thing I can add is that the autothrottle switch is not the only thing that determines whether the servos should be activated. You also need another input to be active such as TOGA or Speed switches. The A/T switch is really an A/T ARM switch & not A/T activate.

Maurice