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Old Oct 05, 2011, 05:09 AM
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vineet_p's Avatar
India, Andhra Pradesh, Hyderabad
Joined Aug 2011
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Help!
Is throttle signal same as servo signal????????

I plan to buy this 2.4GHz 6Ch Tx+Rx combo pack: http://thehobbyshop.in/index.php?mai...products_id=48 . Out of the 6 channels available, how many are throttle channels and how many are servo channels? I see that it is computer-programmable. How can i convert a servo channel into a throttle channel and use it to drive an ESC?

Vineet
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Old Oct 05, 2011, 06:13 AM
Kamikaze Ace
Glacier Girl's Avatar
USA, FL, Lakeland
Joined Jan 2010
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Gotta ask first, why 4 throttles?

And it depends on the software capabilities. Not to mention having to take a part the tx and remove the springs so you don't have auto centering on three of the stick positions.

Would be much simpler to assign mixes to one stick for 4 motors, then to try and operate 4 motors off of say two sticks, if the tx is capable.


And if you wold be able to assign motors to the sticks, all you would have left is switch controls for your control surface operation.

Are we trying to build a quad copter?
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Old Oct 05, 2011, 06:36 AM
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vineet_p's Avatar
India, Andhra Pradesh, Hyderabad
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Quote:
Originally Posted by Glacier Girl View Post
Gotta ask first, why 4 throttles?

And it depends on the software capabilities. Not to mention having to take a part the tx and remove the springs so you don't have auto centering on three of the stick positions.

Would be much simpler to assign mixes to one stick for 4 motors, then to try and operate 4 motors off of say two sticks, if the tx is capable.


And if you wold be able to assign motors to the sticks, all you would have left is switch controls for your control surface operation.

Are we trying to build a quad copter?
Because I am complete beginner, I could get only a gist of your reply. What are 'MIXES'?

Vineet
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Old Oct 05, 2011, 10:18 AM
Jack
USA, ME, Ellsworth
Joined May 2008
16,857 Posts
The originally posted info was wrong and is deleted for that reason, my apologies if I created any confusion...

Jack
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Old Oct 05, 2011, 12:14 PM
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Lnagel's Avatar
Moab, Utah, USA
Joined Apr 2003
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Jack, that is a completely incorrect description of the throttle channel and you are leading the poor OP astray. If you don't think so then just hook a servo up to the throttle channel and you will see that it works just like any other channel.

vinnet, the outputs of all channels on both the transmitter and receiver work exactly the same. Even though one channel may be designated as the throttle channel, you can actually use any channel that you want as the throttle channel. Just be aware that even though the outputs are the same electrically, the transmitter control stick that is normally used for the throttle is usually ratchetted so it will hold any position within its travel range instead of being spring loaded to the center position. So if you do use other than the designated channel for the throttle, you may want to make some physical changes to the sticks.

Larry
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Old Oct 05, 2011, 03:17 PM
Jack
USA, ME, Ellsworth
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Quote:
Originally Posted by Lnagel View Post
Jack, that is a completely incorrect description of the throttle channel and you are leading the poor OP astray. If you don't think so then just hook a servo up to the throttle channel and you will see that it works just like any other channel. <snip> .

Larry
Then correct the description or post the correct description instead of just badmouthing my attempt to help him. It was my understanding that it worked that way.

Jack
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Old Oct 05, 2011, 04:48 PM
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Moab, Utah, USA
Joined Apr 2003
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I already posted the correct description. All of the channels, including whichever channel is used for the throttle, work exactly the same. If the throttle channel worked as you described it, when a servo is plugged into that channel the servo would be centered with the throttle stick in the closed position and would drive to one end or the other with the throttle stick at full. It just doesn't happen that way. If it did then servos could not be used to control the throttle on IC engines.

If you call attempting to correct the erroneous information you posted badmouthing, then so be it.

Larry
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Old Oct 05, 2011, 10:01 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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The originally posted info was wrong and is deleted for that reason, my apologies if I created any confusion...

Jack
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Old Oct 05, 2011, 10:21 PM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
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Jack, many ESCs will just take whatever the signal (stick position) is on startup and call it zero throttle, and anything below that is also considered zero. If the knob on the servo tester is centered when you apply power, it's quite possible that the ESC just sets its throttle endpoint so that the signal it's getting is the 'zero throttle' command, and then it just goes from there.

Try plugging a servo into the throttle channel on a receiver and cycle the throttle stick. It'll move just like it would on any other channel, indicating that the signal it's getting is exactly the same. As long as you're at it, plug an ESC with an unpropped motor into your elevator channel and see if it arms with center stick being zero throttle.

Also try turning the knob on your servo tester all the way down before you power up the ESC.
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Old Oct 06, 2011, 02:46 AM
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India, Andhra Pradesh, Hyderabad
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Thanks!

Thanks for the replies guys!

Vineet
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Old Oct 06, 2011, 10:49 AM
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Moab, Utah, USA
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Jack, that is definitely not normal ESC behavior. As a safety feature most ESCs these days will not arm unless the control signal is 1 msec or less, which represents the throttle stick being closed all of the way. My guess is that you have either an old or a very cheap ESC that does not incorporate that feature. Another possibility is that your servo tester is not putting out the correct length of control pulses. In any case the way it should work is that the ESC will not arm and the motor will not turn until you turn the servo tester all of the way CCW. Once the ESC arms then full CCW on the tester would turn the motor off, mid position on the tester would be half throttle and full CW on the tester would be full throttle.

Although I've never seen an ESC that takes any power up position of the control as zero throttle, TP16 may be right in that the ESC is seeing the initial mid position of the tester as zero throttle position. To verify that just do as he reccomended and power up the ESC with the servo tester turned all the way CCW. The ESC should work normally with the motor shutting down only when the tester is fully CCW.

Quote:
The situation I described is to "drive an ESC" as that is what the question was. If it is different for a servo controlling the throttle on a I.C. motor, I know nothing about that.
ESCs and IC engine throttle servos are driven exactly the same way. If that were not the case then the transmitter would have to be modified everytime one switched from an electric powered airplane to an IC powered airplane. Either that or the IC plane would have to use a special servo for the throttle, which they do not. They use standard servos to control the engine throttle position.

Larry
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Old Oct 06, 2011, 12:45 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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I just finished playing with a motor, ESC (CC Phoenix 80), TX (JR XP6102), and servo tester again and have, as a result, amended my erroneous posts above.

And my apologies for any confusion I may have caused.

I realize now that I misunderstood, how a throttle works, how my servo tester works in one of the three modes it can be used in, and I also did not understand what the actual values were that were involved in the throttle signals.

In hindsight, I realize I knew nothing and shouldn't have gotten involved. So now I'm older and smarter in more way than one.

Jack
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Old Oct 06, 2011, 01:08 PM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
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Jack, some guys would sit there and defend their point endlessly, even once they realized they were wrong. Obviously you're smarter than them No harm done here...
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Old Oct 06, 2011, 02:57 PM
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Moab, Utah, USA
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Hey Jack, we all make mistakes. I even thought I did once, but I was mistaken. Learning from our mistakes is the important thing.

Cheers,
Larry
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Old Oct 07, 2011, 05:36 AM
Bitten by the RC Bug....
vineet_p's Avatar
India, Andhra Pradesh, Hyderabad
Joined Aug 2011
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:-)

Quote:
Originally Posted by Lnagel View Post
Hey Jack, we all make mistakes. I even thought I did once, but I was mistaken. Learning from our mistakes is the important thing.

Cheers,
Larry
That's a good ending

Vineet
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