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Programming end points

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Old 08-02-2003, 03:59 AM
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Crash90
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Default Programming end points

When centering 2 Hitech 5925 servos and programming end points is there a certain degree of deflection I should try to achieve? They will be going into a 1/3 scale 3D plane.
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Old 08-02-2003, 05:29 AM
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Default Programming end points

Are you using the Hitec programmer?

You can program the servos for the maximum travel available (up to 90 degrees per side, all other servos max out at 60 degrees) to the surface, dependent upon the servo arm and control link setup you have.

I program mine in a setup fixture or jig for center and end point. The fixture has mounts for the servo and then I have a control arm with a six inch pointer which indicates where the servo is at. An eight inch degree wheel is mounted to the fixture.
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Old 08-02-2003, 10:43 AM
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Default Programming end points

Yes I am using the hitech programmer. Is there any disadvantage to programming the hitech servos endpoints beyond the 60 degree point? That seems to be the standard.
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Old 08-02-2003, 11:48 AM
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Default Programming end points

Hi Mike. Maybe I should ask this in the HiTech forum, but I know you have a slew of 5945's in your bigger planes and can answer some questions myself and others may have about programmable servos in general. I just picked up a couple of 5945's to play around on the bench a little. Also have the programmer which I consider a must have, even without programmable servos. My questions are these:
1. I noticed that the servos come through with a 4us deadband.
Why is that? I'm not an electronic whiz, but generally don't we want a tighter deadband, or why wouldn't we?
2. Do you keep your travel limits within the 900~2100us range?
3. What are some of the "do's" and "don'ts" of programming servos?
Thanks and take care_bob
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Old 08-03-2003, 12:49 PM
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Default Programming end points

Originally posted by Crash90
Yes I am using the hitech programmer. Is there any disadvantage to programming the hitech servos endpoints beyond the 60 degree point? That seems to be the standard.
Unless you intend to use maximum travel volume I'd say there was no advantage. If you need the throw there is no reason that I am aware that makes the 90 travel arc detrimental.
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Old 08-03-2003, 01:12 PM
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Default Programming end points

My questions are these:
1. I noticed that the servos come through with a 4us deadband.
Why is that? I'm not an electronic whiz, but generally don't we want a tighter deadband, or why wouldn't we?


Are you suggesting the db is 4us as received form Hitec? I never checked what the factory supplied setting was or is. I always reset them and set everything myself. Less is better.

2. Do you keep your travel limits within the 900~2100us range?

I adjust my ATV or End points to maximum available travel within the TX and then program the servos for maximum travel arc of 90 degrees per direction, initially. If I find I use much less than 90 degrees I reprogram the servos reactive range to accommodate the need. The servos range is not directly correlated to 900-2100us. If I recall the range of the servo is 225-0-225.

You can observe the actual transmitted "usec" control signal with your programmer and RX. I find that at maximum ATV at the tX these numbers generally are not seen. In some cases specific mixes, trim adjustments and conditions may allow the TX to transmit outside these parameters. This was the crux or original problem realized by Hitec when modelers were using TX's other than Hitecs. It was resolved by broadening the servo acceptable usec range, if I recall 750-2250usec was settled on as maximum allowable control signal input parameters for the servos.

3. What are some of the "do's" and "don'ts" of programming servos?

I can't offer any thing along these lines. I have yet to find any problems that would cause me to believe there were any concerns. I think you'll find the primary "duh" is that when you have matched all your servos center and end-points and hook it all up you realize hey whats up with the center not being centered or the end-point travels not equal. The problem lies within the TX and it's actual transmitted control signal. Seems the Tx's may not be tuned to transmit exactly 1500us for center or 900/2100 for end points. There is some percentage of acceptable + and - tolerances that are allowed by the factory, this together with the potentiometers, gimbals and and such allow for the less than exact allowable transmitted control signals. What many do is match the servos to the actual TX and control surface in use, I ususally don't go this route.
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Old 08-04-2003, 08:48 AM
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Default Programming end points

Thanks Mike! I quickly put one of the new servos on the tester and yes, the deadband was 4. Thanks for the info_bob
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