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Throttle servo with AR7000

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Old 04-05-2010, 09:02 PM
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Pale_aileron
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Default Throttle servo with AR7000

Should I only use a digital servo for the throttle with the AR7000 receiver? When I try to use a standard JR NES 537servo it jumps around upon power-on. Also what is the best throttle servo to use for a 50cc engine?

Thanks,
mlt
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Old 04-05-2010, 10:00 PM
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gmohr
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Default RE: Throttle servo with AR7000

I think its "jumping around" on power up because your power off fail-safe position is not correct. Rebind with the throttle at low power and see if that helps.

-G
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Old 04-05-2010, 11:19 PM
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Default RE: Throttle servo with AR7000


ORIGINAL: gmohr

I think its ''jumping around'' on power up because your power off fail-safe position is not correct. Rebind with the throttle at low power and see if that helps.

-G
The failsafe position seems to be holding. When I shut off the transmitter the throttle powers down to the low throttle position and stays there. The problem occurs on power-up. The throttle servo moves past its low-throttle position, going to the end-of-travel position and putting a bind on the linkage. Then, after a few seconds, it returns to the normal low throttle position. It's during the boot-up process of the receiver that only this analog servo does this. The digital servos I have don't exhibit this behavior.
Still stuck but thanks for responding.

mlt
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Old 04-05-2010, 11:24 PM
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Default RE: Throttle servo with AR7000

Did you try the rebind?

Regards,
G
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Old 04-06-2010, 07:35 AM
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Default RE: Throttle servo with AR7000

It's not all that unusual and seems to only happen (to me in any case) with Hitec analog servos. I have a 2.6m scale sail plane that runs the retract and tow release back and forth at power up.

Yes, I'm well versed in setting up Spektrum radios.
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Old 04-06-2010, 11:04 AM
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Default RE: Throttle servo with AR7000

Hey Andy,

Are you running the 9 channel rx's on that sailplane?

It seems there is an issue with the 9 channel and above setups when running analog servos cycling on powerup of the rx. I've seen it not only with the Hitec analogs but I have a 33% Edge with an analog servo left on the choke and it will cycle on power up, it's a Futaba analog servo....

According to what I've seen posted over on FG, the 9 channel setups send out a pulse in the 700 range on powerup which isn't seen on the 7 channel rx setups. Whether it would do the same thing with the 2048 resolution capable rx's and a 2048 capable tx with analog servos I don't know as I've not tried it but the speculation is that it has something to do with the rx setup trying to figure out if it's going to run in the higher resolution.

Only solution seems to be digital servos and since this quirk has shown up, I've started using strictly digital servos on my 9 & 12 channel rx equipted models including the chokes and throttles.

I've not seen anyone post that this issue is apparent on the AR-7000 rx's so I'd suspect that the OP has some other problem.
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Old 04-06-2010, 11:40 AM
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Default RE: Throttle servo with AR7000

Hmm....I havent followed the threads over there. Yes its a 921 running on an X9303 with 2048 resolution.
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Old 04-06-2010, 11:40 AM
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Default RE: Throttle servo with AR7000


ORIGINAL: gmohr

Did you try the rebind?

Regards,
G
Yes I did... several times through the switch harness and then directly plugging in the battery to the receiver with the bind plug in the battery port. The servo returns to its failsafe position but still pulses to it's extreme travel endpoint on bootup. For any other use it wouldn't matter all that much but a servo for the throttle needs to startup in the closed position and stay there. unless I could get it to pulse on bootup in the other direction so as not to bind the linkage in its fully closed position.

Cheers,
mlt
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Old 04-06-2010, 08:22 PM
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Default RE: Throttle servo with AR7000

Ok fair enough. I had a very similiar problem once that I cured with a rebind.

Good luck!
G
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Old 04-06-2010, 11:59 PM
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Default RE: Throttle servo with AR7000


Contacted Horizon Hobby about digital vs analog servos with a 2.4 Spectrum and they confirmed that you need to use a digital servo for throttle so you don't get that boot-up pulse that analog servos misinterpret as a movement command. I have another JR DS811 on a plane and it doesn't jump around upon boot-up so I think that pretty much settles it. Thanks for all the input.

later,
mlt
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Old 04-07-2010, 07:57 AM
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Default RE: Throttle servo with AR7000

Good to know, but strange. I've never read anything about this requirement, and indeed I've used analog servos on throttle before without noticing behavior like this.

Regards,
George
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Old 04-07-2010, 10:02 AM
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Default RE: Throttle servo with AR7000


ORIGINAL: gmohr

Good to know, but strange. I've never read anything about this requirement, and indeed I've used analog servos on throttle before without noticing behavior like this.

Regards,
George
Well for what it's worth guys; my experience and what I've seen posted from guys over on FG where lots of the giant scale guys hang out so lots of 'em are running 9 channel setups, is that this problem only shows up on the 9 channel and above rx's running with 9 channel and above tx's which run in 2048 resolution vs the 1024 resolution that most of the 7 channel rx's use.

I've seen this on my Edge which has an R-921 rx, using both an X9303 and my 12X tx's. I do keep a couple of glow models around running AR-7000 or AR-6200 rx's and have not seen this issue with those and they all have analog servos installed at all positions. The only time you see servos move on those at rx powerup is if a post setup re-bind has not been done to establish servo position while the rx is waiting to link with the tx. I do not know if this issue would show up with the couple of 2048 resolution capable 7 channel rx's as I don't have any of those.
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Old 04-07-2010, 10:43 AM
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Default RE: Throttle servo with AR7000

Just thinking out loud here...
When the receiver boots, to keep from arming speed controllers by accident there's nothing applied to the signal pin on the throttle channel until it links up.
Wonder if some servos that get power, but no signal, just don't know how to deal with that....
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Old 04-07-2010, 01:47 PM
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Default RE: Throttle servo with AR7000


ORIGINAL: Zeeb
Well for what it's worth guys; my experience and what I've seen posted from guys over on FG where lots of the giant scale guys hang out so lots of 'em are running 9 channel setups, is that this problem only shows up on the 9 channel and above rx's running with 9 channel and above tx's which run in 2048 resolution vs the 1024 resolution that most of the 7 channel rx's use.

I've seen this on my Edge which has an R-921 rx, using both an X9303 and my 12X tx's. I do keep a couple of glow models around running AR-7000 or AR-6200 rx's and have not seen this issue with those and they all have analog servos installed at all positions. The only time you see servos move on those at rx powerup is if a post setup re-bind has not been done to establish servo position while the rx is waiting to link with the tx. I do not know if this issue would show up with the couple of 2048 resolution capable 7 channel rx's as I don't have any of those.
[/quote]


I'm actually using 2 AR-7000's in a split configuration on an 88" EXtreme Flight Extra 300 for redundancy. Is there any way to find out what the resolution of the AR-7000 I'm running has? Are some of them now coming out at 2048? Does the higher resolution mean you have more precision running the servo?

As for others not having the servo pulse... it may just be with the JR 537 servos that can't handle the 2.4 ghz.
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Old 04-07-2010, 02:50 PM
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Default RE: Throttle servo with AR7000

AR7000's run in 1024 resolution.
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