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Old Sep 09, 2014, 07:01 PM
They Call him Dead!
United States, SC, Pawleys Island
Joined Jul 2003
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I remember asking my Grand Dad "when are we going to go do so and so?" He would always say, "oh we'll go directly."
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Old Sep 13, 2014, 01:08 PM
Yep! I'm addicted.....
mash76's Avatar
United States, AZ, Mesa
Joined Mar 2012
257 Posts
Quote:
Originally Posted by ozyfly View Post
Hi Jay,

I think I am out of luck on the voltage sensor. I had a dig through past posts and it would appear that an earth is required, however the necessary earth will disable the optocoupler protection in the ESC. Seems this has been an issue since 2011 that Hitec have not been able to addressed adequately. I did have plans to fit out my other HV electrics and fit the voice module the the 9X, but will not go there now unless there is a reliable solution that does not compromise the safety features of the ESC I have installed. Somewhat disappointed that the manufacturer appear not to have addressed the issue in 2 1/2 years given the proliferation of larger aircraft flying on HV setups.
I had the issue when trying to use it on a 12s setup all you have to do is ground the neg from the battery to neg on any of the servo leads going to the receiver. Im at work right now but could post a pic of what I did probably tomorrow to show an example.
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Old Sep 13, 2014, 07:16 PM
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acesimmer's Avatar
United States, NV, Fernley
Joined Oct 2011
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You must have a connected ground to make this work.
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Old Sep 13, 2014, 07:44 PM
SAM Elec GrdChmp04,07,10,12,14
Jay Burkart's Avatar
Smithfield, Ky.
Joined Sep 2001
1,073 Posts
Connecting a ground or negative wire to the receiver defeats the purpose of the optically coupled ESC. That assumes that this setup really needs the opto feature.
Personally I've never needed an optically coupled system since we now have brushless motors.
The old brushed motors would make a lot of electrical noise from the sparking and that would couple back into the old radio system and cause problems way back in the old days but todays motors and systems are very much more immune to these issues.
Jay
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Old Sep 13, 2014, 09:53 PM
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acesimmer's Avatar
United States, NV, Fernley
Joined Oct 2011
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The receiver is ground connected when you connect the SPC port to the bats or add a BEC. The ESC is still optically decoupled.
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Old Sep 13, 2014, 10:13 PM
SAM Elec GrdChmp04,07,10,12,14
Jay Burkart's Avatar
Smithfield, Ky.
Joined Sep 2001
1,073 Posts
Quote:
Originally Posted by acesimmer View Post
The receiver is ground connected when you connect the SPC port to the bats or add a BEC. The ESC is still optically decoupled.
I am sorry but I respectfully disagree.
When you use a Opto ESC you are trying to isolate the motor system away from the Receiver/servo system. The opto portion of the ESC keeps ground from the ESC and Motor battery from being carried to the receiver. As soon as you tie the motor battery by grounding it to the receiver you defeat the opto isolation.
You put the receiver directly tied to the ground same as the motor battery and ESC ground. What the Opto system does is isolate the plus and minus section of the ESC away from the receiver by isolating the servo connection from the ESC.
A separate BEC will also defeat the opto feature since it relies on battery minus and then carries that ground on to the receiver.
The only way to keep the opto is a separate receiver/servo battery pack that is isolated from the motor battery.
I'm not clear if the SPC will cause the same issue but since it's feature is to run the receiver directly from the motor battery then it would seem to have the same issue with a ground in common with the motor battery and then the ESC carried right over to the receiver.

I'll be gone for a week or so, on my way to the SAM Championship tomorrow for competition.
Regards,
Jay
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Last edited by Jay Burkart; Sep 13, 2014 at 10:20 PM.
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Old Sep 13, 2014, 10:31 PM
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acesimmer's Avatar
United States, NV, Fernley
Joined Oct 2011
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You may be correct in one way. I understood that the opto was to isolate the throttle optically? not the power bus. So if you purchase an Opto ESC with no BEC then it defeats the purpose in the first place unless like you said a separate battery. But then some telemetry features would not work? The idea is that there is no direct electrical connection between the receiver and the noisy/power end of the ESC, therefore stopping electrical inteference from travelling down the wiring into the receiver. The receiver powers the Opto side of the ESC anyway.
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Last edited by acesimmer; Sep 13, 2014 at 10:38 PM.
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Old Sep 14, 2014, 09:36 AM
SAM Elec GrdChmp04,07,10,12,14
Jay Burkart's Avatar
Smithfield, Ky.
Joined Sep 2001
1,073 Posts
Quote:
Originally Posted by acesimmer View Post
You may be correct in one way. I understood that the opto was to isolate the throttle optically? not the power bus. So if you purchase an Opto ESC with no BEC then it defeats the purpose in the first place unless like you said a separate battery. But then some telemetry features would not work? The idea is that there is no direct electrical connection between the receiver and the noisy/power end of the ESC, therefore stopping electrical inteference from travelling down the wiring into the receiver. The receiver powers the Opto side of the ESC anyway.
Ace simmer,

That is right, you are isolating the motor, battery and ESC away from the receivers electronics entirely, at least the direct connection which typically is the worst interference source. There are NO opto ESC made with a BEC since a BEC needs to be connected to the receiver and servos to do it's job. Actually opto isolated ESC's came out a long time ago when we were flying 72mhz and 35 MHz radios which had less noise rejection and not as sophisticated encoding like todays Spread Specktrum type radios on significantly higher frequencies.
Also the opto portion of the ESC gets all of it's power from inside of the ESC on power supply running it's circuitry and the only opto part is the optical isolation of the throttle signal into the ESC, so that is optically coupled into the throttle control function.
Regards and thanks,
Jay

Right now waiting on my flying buddy to get here to load up and go up to the Championships in Muncie.
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Old Sep 14, 2014, 06:39 PM
Yep! I'm addicted.....
mash76's Avatar
United States, AZ, Mesa
Joined Mar 2012
257 Posts
I'm not a electrical engineer but if you have no BEC In your ESC this is how you get the telemetry to work. Whether or not it's the best was to do it it's what works.
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Old Sep 17, 2014, 06:10 PM
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Va.Beach Va.
Joined Feb 2007
253 Posts
Why do you need to isolate the motor from the receiver. I have never had any problems with glitching since the days of fm and a whole Lotta FM guys standing real close bumping antennas.
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Old Sep 17, 2014, 10:44 PM
SAM Elec GrdChmp04,07,10,12,14
Jay Burkart's Avatar
Smithfield, Ky.
Joined Sep 2001
1,073 Posts
Quote:
Originally Posted by Little ROG View Post
Why do you need to isolate the motor from the receiver. I have never had any problems with glitching since the days of fm and a whole Lotta FM guys standing real close bumping antennas.
There were occasions where the motor sparking from the brushes on brushed motors would cause glitching on the radio setups because of the induced noise into the receiver. It didn't always happen but it did cause problems and the use of the Opto coupled ESC would reduce or eliminate this issue.
This was especially a problem on some of the very large motors. Like I mentioned with the advent of the brushless motors and Spread Spectrum radios we now use this problem where a Opto ESC is needed have greatly diminished.
Jay

Back from the SAM Champs this evening..................Had great time and scored well....
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Old Sep 18, 2014, 04:48 PM
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Va.Beach Va.
Joined Feb 2007
253 Posts
Got it. That was kind of where I was going with that one. I thought no bec in the speed control ment cheap but you still need some kind of bec. I really don't think anyone is gunna get much feedback if they use optic receivers they probably have more built in filters than they can explains to us. I used an old 8 channel FM receiver pulled the case off and stuck it in my glider with a brushed 600 motor zero gliching not even a tick. The receiver is probably at least 15 years old
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Old Sep 18, 2014, 06:38 PM
Yep! I'm addicted.....
mash76's Avatar
United States, AZ, Mesa
Joined Mar 2012
257 Posts
High Voltage ESC's typically have no BEC built in, since most planes that are running a HV setup typically are also running HV servos and can be operated directly on a 2s lipo without a BEC. This is the only time you have to worry about running a ground to make the telemetry work properly.
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