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Thread: adding expo curve makes first half of trigger pull do nothing.

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Old 11-13-2019, 11:01 AM   #1
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Default adding expo curve makes first half of trigger pull do nothing.

Hey, newb here shopping for my first radio (in about 3 decades). I picked up a Flysky GT3C and noticed a problem. Turning down the throttle end point or adding an expo curve makes the first half of the trigger pull do nothing. Doing both made the vast majority of trigger travel do nothing. I returned it an got a Spektrum DX5C but it has the same issues. Is this normal? At what price point or with what model controller would this not be a problem? I don't want to keep buying and returning radios. The issue can be seen here:

https://www.youtube.com/watch?v=3Q7U5U_Dhjw&t=151s

Thanks!
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Old 11-13-2019, 11:27 AM   #2
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Default Re: adding expo curve makes first half of trigger pull do nothing.

This is expected behavior. That dead zone is your neutral range. Also this is part of the reason why expo on the esc is better then in the transmitter.

You can set your neutral range to 0.02, turn the pwm up and turn up your initial start force to make it better.

If you want to reduce the top speed you can also do that in the esc and it will work better.

Changing this stuff on the transmitter is quick and dirty, with emphasis on the dirty.

A castle esc with castle link will give you a much better throttle curve.

Think of it like this. Your motors minimum speed is say 6% on the trigger before it moves (set by the esc, think of it like esc slop maybe? ) . Now you drop your max speed on the transmitter to 1/3rd. That pushes up the minimum start to 18%. Now you add some curve extending the low end resolution on the transmitter further pushing up that minimum start speed.

You don't get slower minimum speeds by adjusting the transmitter. Those just help if you have clumsy fingers.

Any ways play with you esc some, you can gain some of that back.

I would remove the throttle curve entirely from the transmitter, and practice finger control or reduce the start punch for smoother takeoff.



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Last edited by Voodoobrew; 11-13-2019 at 11:37 AM.
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Old 11-13-2019, 11:29 AM   #3
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Default Re: adding expo curve makes first half of trigger pull do nothing.

When the light on the esc changes and the car isn't moving, that's dead one on the esc you need to look at.

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Old 11-13-2019, 11:34 AM   #4
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Leave the trim at 0 ALWAYSE this changes your neutral point, it's just the wrong way entirely to accomplish this goal.

Might cause the car to not turn on.

And if you recalabrate with your Tim set like this, your go a have headaches...

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Old 11-13-2019, 11:43 AM   #5
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Basicaly your blaming the controller for an issue that is in the vehicle.

Hope that helps.

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Old 11-13-2019, 12:04 PM   #6
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Excellent answers Voodoobrew!
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Old 11-13-2019, 12:07 PM   #7
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Yeah I agree with Voodoo this is normal and the worst way to accomplish a throttle curve. When a throttle curve is used on the ESC (where supported) the results are much better and there will be no giant dead zone on the throttle.
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Old 11-13-2019, 12:23 PM   #8
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Picture of what im saying
you want to make the red line lower
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Old 11-13-2019, 12:27 PM   #9
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Holy crap. Lifesaver, Voodoo. I have no idea what pwm is but I made all the adjustments you suggested on the ESC and it makes a huge difference. Thinking of the slop being in the ESC makes everything make more sense too. I'm going to delete that youtube video as I don't want to give flysky a bad name. I tried the expo on the radio, and even though it's still 'dirty', it's much better than it was (yes, just looking for a bandaid for my clumsy fingers). Thanks! If you're ever in L.A. (lower Alabama) I'll buy you a WYNONA'S BIG BROWN ALE.
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Old 11-13-2019, 12:39 PM   #10
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Thanks

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Old 11-13-2019, 02:21 PM   #11
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Default Re: adding expo curve makes first half of trigger pull do nothing.

PWM= Pulse width modulation

https://en.m.wikipedia.org/wiki/Pulse-width_modulation
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Old 11-13-2019, 10:51 PM   #12
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Default Re: adding expo curve makes first half of trigger pull do nothing.

Pwm may add a bit to get you moving sooner and more smoothly. Mostly I just turn it up to quiet things down. I believe it will reduce torque a tiny bit.

My best guess is high pwm enhances 5 slot motor benefits and low pwm enhances 3 slot benefits. Like tuning.

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Old 11-13-2019, 11:22 PM   #13
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Default Re: adding expo curve makes first half of trigger pull do nothing.

While we’re talking about it, I will note that the Exponential capabilities on my GT3C are quite lacking compared to my DX4C and DX5 Rugged.

I use Expo on the steering channel when running Scale Ultra style, as steering while physically running is anything but precise, and a good 30-50% expo helps a lot in keeping the rig from going all over the trail.

While setting up both FlySky and Spektrum radios to do this, the expo all but doesn’t exist on the GT3C. It’s stupid and erratic. While The Spektrum radios display a proper exponential output on the steering ch.
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Old 11-21-2019, 06:16 PM   #14
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Default Re: adding expo curve makes first half of trigger pull do nothing.

I have 3 flysky gt3c's and the expo doesn't work properly on any of them. If I use it to tame the throttle than reverse gets touchy, and if used on the steering than one way gets smoother off center while the other direction gets overactive. It's like the expo reverses once past the centrepoint. Very annoying. Luckily I run castle esc's and program my expo through castlelink.
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Old 11-21-2019, 07:35 PM   #15
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Default Re: adding expo curve makes first half of trigger pull do nothing.

The hacked Flysky gt3c has working expo. It is one of the features of the hack. There is a great thread on how to do the hack and it is quite easy and cheap (less than $8 in electronic bits off ebay). Worth doing just for working expo.
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