Hello all,Sorry to bug everyone here again, but I'm a bit of a newb when it comes to the whole home cockpit thing :)I'm looking at building a generic panel (a small box, really) with a couple of throttle levers, and some of the more common switches. (lights, autobrake etc.)I have looked over a few tutorials regarding auto-throttles via servos, and it doesn't sound all that difficult (tedious, getting everything properly aligned but not difficult) But one thing continues to stump me.I would probably end up using a Phidgets 4 servo controller, and 2 Hi-tech HS815BB servos. What I'm concerned about is driving the servos. I could tell the software to just move the servos to match the throttle position, but when the autothrottle is disengaged, I'm afraid I would be constantly fighting the servos (due to the positions not always matching 100%, and any applicable delay (ie: if it takes .1 seconds for the SW to calculate the throt. position and move the servo accordingly, it would always be trying to move the throttle to where it was .1 seconds ago)The HT 815BB servos require a seperate power supply anyway, so the only idea I have been able to come up with is this:Use a Phidgets relay board to switch the power to the servos on/off with the A/T (ie: if the A/T is on, switch the power to the servos on, else switch it off) Diagram:Servo---control wire (white)--------Servo Controller | | |Servo Power wire | | |Power Supply---------Relay Controller----------Power outlet This would work, I think, but I wanted to ask if anyone had a better idea, or have used this solution. I know there are people out there who have constructed auto throttles and wanted to get their input regarding the issue(BTW, The person who's tutorial I read used a manual toggle switch to switch the power on/off when the A/T is engaged, but I would like to find a more elegant (and automated) solution :) )Thanks, -Chris

Well, how about a couple of microswitches either side of the throttle bar, so that when you manually move the throttle against the resistance of the servo, the switch is closed and the A/T is disengaged?That, I believe, is how it functions in the RW - if the pilot manually moves the throttle, the A/T disengages.Richard

I think the best solution is to use a DC motor, not a servo motor or in last case, use a modified servo motor for unlock.In this example, our friend make a motorized auto-throttle with a little IOCard circuit published in opencockpits for control a DC motor.Position is controlled using a potentiometer and a SIOC program for move throttles...http://www.opencockpits.com/modules.php?na...p=getit&lid=188

>I think the best solution is to use a DC motor, not a servo>motor or in last case, use a modified servo motor for unlock.>Position is controlled using a potentiometer and a SIOC>program for move throttles...Isn't this exactly what a servo is ?A motor with positional feedback for control.The pot provides feedback about the real motor position to which a control circuit/algorithm can react in order to move the motor to the intended/target position.Manuel

Thanks for the help everyone!I'm still a bit unsure of why exactly a DC motor and a pot would be better than a servo? (except of course, for being able to produce significantly more torque) I'm thinking I'd rather just use the pre-built servo. I may have been unclear in my original posts, since the replies are more geared towards how to disengage the A/T when I move the throttles. Something I hadn't thought of. (I like the microswitches idea. Will have to see if I can make it work)I was more concerned about keeping the servos from trying to move the throttle when the A/T is disengaged. (ie: if I disengage the A/T, and start hand-flying; wouldn't the servos still be trying to move the levers?)I picked up a couple of $0.50 relays at Radio Shack. I'll play with them and see what I can come up with :)-Chris

A RC Servo motor have a limit movement of aprox. 180 degrees.If you want to control a 737 autoTH for example, you have a clutch and you can choose to control throttle with hands...In this case you cannot have a limit movement...