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Old Sep 25, 2011, 08:27 AM
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It's just relabeled plush/hobbywing/etc, or actually based on programming card, mystery blue.
i.e this http://www.hobbyking.com/hobbyking/s...dProduct=13429
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Old Sep 25, 2011, 08:44 AM
Tri-Quad-Hexa-Octo-copters!!
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Milo,
Arducopter, Ardupirate, Astec X-BL/etc, OpenPilot, Mikrokopter, Conrad Copter, DJIWKMQ, KapteinKuk, MultiWiiCopter, Shrediquette, UAVX @ 40hz, XAirCraft 450/650 and most others sold/built recently can do 400Hz updates or better.
The specifications of ESC updates rates have been the most elusive, but the ones that work well are listed in the Mega Index under Tip 7.
Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index
Quote:
Originally Posted by milo12 View Post
To add to Justin's question - What controllers can update at 400hz or greater?
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Old Sep 25, 2011, 08:06 PM
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Our eRC ESC's also update at 400Hz and work very nicely in multi rotor aircraft. I'm working on my second quad right now. I've got the bug, this stuff is all I can think about lately.

Jason Cole
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Old Sep 25, 2011, 08:14 PM
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Yes, yes, they all do. They're also all from the same factory with same firmware.
Every different place just charge $10 more for them.

I won't believe your "400Hz response" claim unless you run the tests listed here : http://www.rcgroups.com/forums/showthread.php?t=1250488 (or send me a unit to run them), and show significant response improvement over say tgy plush or etc.

Just saying "works great for multicopter" doesn't really cut it. Where are test results.
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Old Sep 25, 2011, 08:23 PM
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eRC ESC = ZTW right? And AFAIK Mystery Blue Series is also = ZTW.
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Old Sep 25, 2011, 08:53 PM
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Oh yeah, one look at eRC pic and I know its mystery, exactly same board design and cap placement. Also, motor reverse by card is a dead giveaway. Might as well jsut buy mysteryblue from HK for $10, same thing.
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Old Sep 26, 2011, 09:20 AM
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Nope, not the same thing. Those are A series controllers with less features. The eRC ones are the only B series ESC's from ZTW with more features, not to mention the warranty and support from Hobby Lobby. Ours may cost slightly more, but it's worth it.

Jason Cole
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Old Sep 26, 2011, 09:24 AM
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Yea yea yea. Please grab mystery30 and your esc, and show me some graphs of performance and "more features" then I'll be convinced... And I have yet to come across an ESC that I didn't abuse that needed "warranty". If they don't blow up on first power-up they'll keep ticking until you break them in half.
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Old Sep 26, 2011, 10:04 AM
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http://www.rcgroups.com/forums/showthread.php?t=1250488

It seems based upon this thread that the Turnigy Plush with the reflashed firmware is about as good as it gets, especially considering the price.

How hard is it to reflash an ESC's firmware?
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Old Sep 26, 2011, 10:07 AM
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It's not too hard, there's a whole thread dedicated to this in DIY electronics.
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Old Sep 26, 2011, 12:18 PM
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Quote:
Originally Posted by timecop View Post
Yea yea yea. Please grab mystery30 and your esc, and show me some graphs of performance and "more features" then I'll be convinced... And I have yet to come across an ESC that I didn't abuse that needed "warranty". If they don't blow up on first power-up they'll keep ticking until you break them in half.
Well for starters the eRC has more programming options and above the 35A ESC they all come have switch mode BEC's with adjustable output voltage. Not saying these are way better or the end all be all of ESC's, just that they are proven to work well at 400Hz, have a good price, are available in the US readily, and are backed up with our support.

Jason
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Old Sep 26, 2011, 07:59 PM
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Man if only we had someone on here working on making us some killer ESCs....
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Old Sep 26, 2011, 10:27 PM
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Quote:
Originally Posted by milo12 View Post
I have seen it stated many times that 400 Hz is a desirable update frequency and that 200 Hz is borderline unstable.

Can someone point me to testing that can support this? I am skeptical because of the basic physics of accelerating and decelerating the air mass out of the propeller. I doubt you can influence it that quickly, after all a propeller is not a speaker.

For example a 6000 rpm prop is spinning at 100 Hz. With a 400Hz update you are trying to change the rpm every 1/4 revolution. I find it hard to believe that any significant acceleration or deceleration can happen in 1/4 revolution, 2.5 milliseconds.

A typical prop weighs 20 - 25 grams. It is spinning at 6000 rpm therefore it has a certain angular momentum and it seems hard to believe it can slow down or speed up any significant amount in 1/4 turn. After all the prop has to change it's velocity enough to change the amount of air it is pushing down. This means the thrust needs to change. How much? I don't know.

Here is a plot from my eagle tree logger collected at 50 Hz. That is not fast enough to capture 200+ hz activity but it shows very little prop rpm change over this 1/2 second. An interesting bit is the watts shows a lot of activity over the same period. I don't know if that is noise/ ripples in the power or what.
You are correct. But faster is always better right? No faster is often a waste. You physically cannot affect a change on a spinning propeller faster than about 50 Hz. So this would be a sine wave PWM input of about 100Hz (one pulse high and one pulse low representing a 50Hz wave). The maximum update that you should need is 100Hz. A good control algorithm can provide stable control with no greater than 100Hz PWM output. Depending on the internal filtering and sampling of the ESC you are using, hitting it with greater than 50Hz PWM can cause aliasing. This can cause instability using some multi-rotor controllers utilizing higher than 100Hz PWM. If you like to talk bandwidth then the bandwidth of typical ESC/Motor/Propeller is about 10Hz (3db point). Discussion about super fast pwm is a waste of time IMHO.
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Old Sep 27, 2011, 08:05 AM
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That looks similar to what Castle Creation guys stated from their lab tests and the reasson of their effort to make a firm update to allows their escs go up to 100hz but not beyond. Hope they do it quickly.
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Old Sep 27, 2011, 08:59 AM
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Hi,
I believe the HoverFly Pro is outputting what you call "UltraPWM" at 198Hz? I agree with George in the attached post here that ESCs with 50Hz update rate are marginal performers for multicopters. For most other multicopters the ESC performance is adequate at 200Hz. When the flight controller supports it, the 400Hz rate is the current sweet spot for PWM ESCs. The unmodded Hobby-Wing ESC manufactured varieties like the Turnigy Plush series and the other re-branded ones recommend in the Quadrocopter and Tricopter Mega Link Index
in Tip 7 all work well and in addition can be updated by some to Quax and Simonk fast PWM firmware that makes them respond even better for multicopter use. Most folks have seen poor performance with Castle ESCs due to the low <100Hz update rates, their particular use of throttle smoothing and ramp up speed and some of their ESCs that use the auto-throttle range calibration which is not compatible for good multicopter performance.

Again, I agree the physics of it is like measuring with a micrometer(gyros and accelerometers) and marking with a grease pencil(FCBs) then cutting with an axe(ESCs/motors/props). However it is obvious that the best performing multicopters use the higher ESC update rate capability, such as the top multicopters that others have been chasing for years like the XBL at 1000hz(note the "famous" lab dancing quad videos), the Mikrokopter at 500Hz, and most other BIY project multicopters, such as the Multiwiicopter, now take advantage of 200-400Hz ESC update rates to increase stability.

Cheers,
Jim

http://www.rcgroups.com/forums/showp...6&postcount=17

Quote:
Originally Posted by S11D336B View Post
I'm sorry guys, but I see lots of bad information here. Let me communicate bluntly but clearly.

1. Most ESCs work with the HoverflyPro. There are only a few we have found that won't work. Of those most wouldn't be suitable for ANY quadcopter (Scorpion, Jetti)
2. Our tests indicate that while a quadcopter could fly marginally with standard 50hz PWM, it's simply not possible to achieve a HIGH level of stability with this.3. You ESCs must have a BEC of 5.5v or less (almost all ESCs have a BEC of 5.0v). If your ESCs don't you'll need to plug a 5.5v or less BEC into one of the following places
a. Any ESC port
b. Any Receiver port
c. Any channel on your receiver
d. Either OSD in or OSD out
4. PWM output frequency depends on the ESC and the motor you are using. Most ESCs don't allow you to choose this setting. If they do, follow the manufacturer's recommendation.
5. PWM input frequency is set by the HoverflyPro and can not be changed, nor should you try to change it.



Brands we have tested and recommend:
Turnigy, RCtimer, TowerPro, Castle Creations, Hobby Wing.
http://www.rcgroups.com/forums/showp...4&postcount=23
Quote:
Originally Posted by S11D336B View Post
We've seen several customers flying with the thunderbird series without a problem. I have not personally tried the thunderbirds, but I have tried the ICE 80 HV. I do not think it would work in auto calibrate mode (we never tried it). We only ever flew with fixed end points mode.

-George
We've only ever had one Chinese ESC fail that wasn't due to overloading or some scenario we caused as users. We find them to be highly reliable.
Quote:
Originally Posted by photronix View Post
You are correct. But faster is always better right? No faster is often a waste. You physically cannot affect a change on a spinning propeller faster than about 50 Hz. So this would be a sine wave PWM input of about 100Hz (one pulse high and one pulse low representing a 50Hz wave). The maximum update that you should need is 100Hz. A good control algorithm can provide stable control with no greater than 100Hz PWM output. Depending on the internal filtering and sampling of the ESC you are using, hitting it with greater than 50Hz PWM can cause aliasing. This can cause instability using some multi-rotor controllers utilizing higher than 100Hz PWM. If you like to talk bandwidth then the bandwidth of typical ESC/Motor/Propeller is about 10Hz (3db point). Discussion about super fast pwm is a waste of time IMHO.
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