Originally Posted by Daddy.

Thanks BF. And WOW! that seems odd. I can see where someone would have a 250 tail and analog cyclic, then upgrade to digital cyclic and potentially burn up the tail servo. All the time wondering what happened.

Has this been explored with John? Or is it firmware bound?

Ken

I'm sorry, but this is documented in the manual, so I do not really see the problem. If fact, it does warn you to not connect any servos before choosing the correct servos type combo. Sigh..

Originally Posted by PHMX

I'm sorry, but this is documented in the manual, so I do not really see the problem. If fact, it does warn you to not connect any servos before choosing the correct servos type combo. Sigh..

Sorry, I wasn't very clear.

Assume you set up a ZYX with 3 analog servos on the cyclic and a digital on the tail. Lets say you have a clone 9257 on the tail that works fine at 250 hz frame rate but would overheat and burn up at 333hz frame rate (not uncommon). You fly for a couple months and everything is fine.

Now let's say you upgrade to digital on the cyclic and change the software to all digital. This, from my understanding of BF's reply, would now set the tail servo at 333 hz frame rate. A couple flights and you loose the tail due to burned up servo.

I don't see any mention or warning for this in the manual, did I miss it? Or did I misunderstand BF?

If not, I think this is an issue. Documentation stating "minimum 250 hz frame rate digital tail servos are ok only with analog cyclic servos. If digital cyclic servos are used a digital tail servo must work with 333hz frame rate".

Better still would be disclosed and selectable frame rates i the firmware/software.

Sorry if I confused anyone or if I am the one confused,
Ken

Originally Posted by Daddy.

Sorry, I wasn't very clear.

Assume you set up a ZYX with 3 analog servos on the cyclic and a digital on the tail. Lets say you have a clone 9257 on the tail that works fine at 250 hz frame rate but would overheat and burn up at 333hz frame rate (not uncommon). You fly for a couple months and everything is fine.

Now let's say you upgrade to digital on the cyclic and change the software to all digital. This, from my understanding of BF's reply, would now set the tail servo at 333 hz frame rate. A couple flights and you loose the tail due to burned up servo.

I don't see any mention or warning for this in the manual, did I miss it? Or did I misunderstand BF?

If not, I think this is an issue. Documentation stating "minimum 250 hz frame rate digital tail servos are ok only with analog cyclic servos. If digital cyclic servos are used a digital tail servo must work with 333hz frame rate".

Better still would be disclosed and selectable frame rates i the firmware/software.

Well, I was referring to what is actually compatible with the ZYX when it comes to servo pulse width types.

It's not uncommon for flybarless units to not support just all known types of servos. (For example 3GX won't work with any analog servos regardless of pulse width and frequency, nor do many other flybarless units work very well with analog servos either (read: slower response, if good performance at all).).

Also, the ZYX doesn't change the actual frequency itself, the thing you get to choose is the pulse frequency width (being 1520us, 960us or 760us).

I do think the higher-end servos with less exotic frequencies do match much better with flybarless units like the ZYX, but I don't think anything gets changed unless the user changes it.

The point I was trying to make is to a.) make sure the servos you intend to use are compatible in the first place and b.) to make sure the settings are adjusted correctly depending on the servo types. Get both right and you won't burn any servos.

Tinkering here or taking a gamble might in fact mean you'll end up burning servos.

I am aware the Hz values aren't mentioned in the PC software version I've got nor the manual, but the servo pulse width in most cases does in fact define most of what a servo needs to be to be really compatible. The warning does clearly state to not connect any servos before selecting the correct servo type.

If a servo is not compatible, you can not select the correct servo type and can't connect the servo. Simple as that, right?

Anyhow, not trying to be tough on you, take a look at this:

Originally Posted by Daddy.

Sorry, I wasn't very clear.

Assume you set up a ZYX with 3 analog servos on the cyclic and a digital on the tail. Lets say you have a clone 9257 on the tail that works fine at 250 hz frame rate but would overheat and burn up at 333hz frame rate (not uncommon). You fly for a couple months and everything is fine.

Now let's say you upgrade to digital on the cyclic and change the software to all digital. This, from my understanding of BF's reply, would now set the tail servo at 333 hz frame rate. A couple flights and you loose the tail due to burned up servo.

I don't see any mention or warning for this in the manual, did I miss it? Or did I misunderstand BF?

If not, I think this is an issue. Documentation stating "minimum 250 hz frame rate digital tail servos are ok only with analog cyclic servos. If digital cyclic servos are used a digital tail servo must work with 333hz frame rate".

Better still would be disclosed and selectable frame rates i the firmware/software.

Sorry if I confused anyone or if I am the one confused,
Ken

Yes, you understand it correctly, and what you are saying can certainly happen. It is a negative with the ZYX. The rule I use now with the ZYX, is spend a little extra on the tail servo and get one that does work at 333Hz. It's a good policy for any gyro really.

The Fitec FS9357D is a good example of a reasonably priced mini tail servo, that does work at 6V and 333Hz.

BF, thanks. FYI (you probally already know) some Goteks 9257's work at 333 and some don't (doing some testing atm). I'm ordering one of the 9357's you recommended to give it a whirl! Thanks, Ken

Originally Posted by Daddy.

BF, thanks. FYI (you probally already know) some Goteks 9257's work at 333 and some don't (doing some testing atm). I'm ordering one of the 9357's you recommended to give it a whirl! Thanks, Ken

I actually found a spec sheet on them looking for a friend and the one I found in China said 80Hz So you may watch them.

First let me apologize to all for this post, ok that's done.

PHMX, don't you think I've seen that screen you posted? Do you realize we're talking about something outside what is listed in the software and manual (digital servos specifications)? Your generalizations that are not on topic do not add to the discussion. Quite frankly they probably confuse people.

May I quote, " learn before you teach" and then learn how to teach with respect and compassion.

Please stop trying to start flames.

Ken

Don't know about flames, but I've certainly burned out a few tail servos with my CX 3x1000. I wholeheartedly agree that it would be much better if we could select the frame rate for the tail servo independently of the cyclic setting - and in fact it would be good to know what frame rate the cyclic servos were driven at, when set to digital.

I've gone thru two HK15158A's - 9257 clones, and I suspect the cause was running them at 6v. Both failures were caused by a burned out motor rather than an amp.

Sadly, I killed my Fitec - but that was probably because I had neglected to do maintenance on my tail, and flying off grass had resulted in severe binding.

Next up was a hitherto trusty Hitec 5084MG. Until it failed, it was working great at 6v, 1520/333 - even better than the Fitec, I'd say. don't know why it failed, there was no binding.

When it died, it gave me a little warning - the tail went really vague for a few seconds, but then the heli started to spin up. I've practised tail failures on the sim, and this was quite like that, with the heli spinning like crazy. I managed to auto down into longish grass with almost no damage - just a cracked canopy. By contrast, both 15158A failures were benign, with the servo dying in the tail neutral position. Maybe I just got lucky and should have bought lottery tickets on those days!

Now I'm slumming it again with another HK15158A. Although the gears are quite sloppy, you can at least buy 15158A's by the half dozen, so you can always keep flying.

I can understand why there would be a limited choice of servo type selections if using TX programming, but surely it should be feasible to have a full range of selections with either the program box or the software.

Shame on you, Tarot and CX, for making a unit that costs so much but offers so little!

I agree the refresh rate could use a little more transparency from both the gyro and servo manufacturers. For example, I doubt the ZYX drives the swash servos at 333Hz. That would probably kill them pretty fast as well as be completely unnecessary. Check out the BX specs for reference: http://www.beastx.com/service_servoliste.html. It drives digital swash servos at a max of 200Hz.

On the other hand, some tail servos are designed to work at 333Hz or even 560Hz and that kind of refresh rate does actually make a difference. On top of that, the tail servo is under a HUGE amount of stress. Much more so than the swash servos, the tail servo is always under load, always moving, making correction against this constantly changing load, and getting position changes from the gyro at a faster rate.

If you keep burning tail servos, it can be one of 2 things: either the servos you're using can't handle the abuse (voltage, load, refresh rate) or you're putting too much load on a servo that should be adequate for the job (i.e. you've got binding).

BTW, for those who may be confused about servo operating characteristics. they are specified by two parameters:
1) center pulse width measured in microseconds: e.g. 1520µs
2) refresh rate (aka frame rate or drive frequency) measured in Hertz: e.g. 333Hz

Originally Posted by beenflying

I'd say it was firmware bound. In the program box you set the frame rate (Hz) and it changes the cyclic to analog or digital based on the table in my last post (works backwards to the PC program). John would have to confirm, but I'm picking they just pass a number from 0 to 5, that equates to the 6 options in the Servo Type tab.

Those settings are firmware bound. As you surmise, its just a single number from 0 to 5, which selects the corresponding combination that they have listed. There is no individual setting of the servo type/frequency.
Maybe someone would like to suggest this to the manufacturer as a desired change to the firmware.

Originally Posted by Daddy.

First let me apologize to all for this post, ok that's done.

PHMX, don't you think I've seen that screen you posted? Do you realize we're talking about something outside what is listed in the software and manual (digital servos specifications)? Your generalizations that are not on topic do not add to the discussion. Quite frankly they probably confuse people.

May I quote, " learn before you teach" and then learn how to teach with respect and compassion.

Please stop trying to start flames.

Ken

You might have seen it, but apparently you failed to comprehend the image, because it clearly demands for compatible servos or you might burn servos. Regardless of whatever else you can do wrong to burn servos.

A handful of people here apparently claim the servo frequency changes upon switching to all digital servos, but that is not the case at all. I'd know, because the servos I am using with the ZYX should not work at 333Hz for very long and I'm using all digital servos from day one.

What's the proof they have for this claim anyway???

I'm not generalizing or flaming, I'm just stating the obvious. And you my friend should really stop making stupid and unfounded accusations.

With any type of flybarless system, you will want to make very sure your servos are compatible with the unit and not 'just hope they will last' and take a gamble. It just doesn't work like that and frankly, the same is true for regular HH tail gyros.

It is my hope that discussion on this topic will influence future firmware from the manufacturer. I will contact them.

With that said, is there a firmware update "wish list" somewhere? And has/is anyone working on a public firmware version (hacked)?

Cheers gentlemen and thanks for all the info,
Ken

I don't get it....
I just received ZYX gyros for my trex 500 and 250.
Which application should I use for initial settings like servo type, reverse, etc... ?
I don't know where to start. The manual just tells about programing via transmiter.
Thanks

Originally Posted by DerClown

I don't get it....
I just received ZYX gyros for my trex 500 and 250.
Which application should I use for initial settings like servo type, reverse, etc... ?
I don't know where to start. The manual just tells about programing via transmiter.
Thanks

You download John's PC software to setup ZYX. You should be able to find the link in the first page of this thread. The version that I am using is 1.21. Once you use the PC software, you won't go back to use the transmitter

Ching-Ho Cheng

Thanks, I'll give it a go