Axial AX-3 Throttle Dual Rate Switch possibility

[DieCastoms]

Hi all. I have an idea for adding a throttle trim to the Axial AX-3 transmitter.

First thing first, lemme get a few things out of the way . . .

Yes, I am a low-post newb.
Yes, I spent about 2 hours searching on this and found nothing, yet.
Yes, I have seen this done before, but not in THIS transmitter.
Yes, I have some experience with electronics, though granted, not enough to be sure my idea will work the way I think it will..
Yes, doing any of this WILL void your warranty.
NO! I will NOT be held accountable if someone should try this and it fries something, through their fault or mine.. this is an IDEA and as such, YOU choose whether to continue or not, not me . . .


Ok, that being said, here is my idea.

The Axial AX-3 transmitter, which comes in the Honcho RTR set, and most likely the others as well, has a dual-rate adjustment for the steering, but it does not have any D/R or limiter for the throttle, other than that offered by changing settings in the receiver.

LosiKid posted this thread with lots of nicely-taken photos of the transmitter, both inside, and out.

The pot for the throttle is connected via 3 wires from the pot to the main board. This can be seen in LosiKid's thread, in the third post, in the third and fourth images.

My idea is to cut the center wire, that's the brown one in LosiKid's images, and add a resistor. Basically what this will do is change the signal sent to the main board from the pot, letting the main board sense that the trigger has not moved as far, mechanically, as it has. This should let you have the full range of the mechanical trigger, but not as much range in the electronic signal... This should give you lower speeds and better control.

When not wanted, a switch could be added to bypass this extra resistor. Going one step further, a key-switch like those found on computer cases could be added to prevent anyone changing the switch unless they have the key.

One step further than that, a variable resistor instead of a fixed resistor should let you adjust how much affect is had on the signal. More resistance should give you less speed.


So that's my idea, adding an amount of resistance to the existing throttle pot to result in lower speeds and higher throttle resolution, for only a few bucks.

I look forward to responses to this, especially from LosiKid who seems to know a great deal about these transmitters and modding.

DieCastoms.

[Draggermirage]

This is easily accomplished using different throttle curves in the stock AE-2 ESC along with just about every other programmable transmitter and ESC.

Simply get a castle Link and reprogram your AE-2.

Marcus

[DieCastoms]

Originally Posted by Draggermirage

This is easily accomplished using different throttle curves in the stock AE-2 ESC along with just about every other programmable transmitter and ESC.

Simply get a castle Link and reprogram your AE-2.

Marcus

I am aware of the settings in the ESC (and actually mentioned them in my original post) but this is not something you can easily change on the fly. Someone who practices could probably re-initialize the ESC and change all the settings, but that's tedious. I am looking for something that could simply be the flip of a switch. My mod SHOULD make that possible.

Once someone tells me, at least, that I am not going to fry something, I will try it myself and post the results. I'm hoping someone who mods will read this and at least let me know I'm not going to cook something . . .

DieCastoms.

[Draggermirage]

Here's my disclaimer. I have never torn down or had to open an AX-3, but do know enough about a Tx's general inner workings to make myself dangerous.

The forseeable issues I see with simply putting a resistor in-line without any other compensation is that it will cause issues with your neutral state and programming with the ESC.

That pot on the trigger has a certain travel (say 0-100%) with a certain ohm load at any given position of the trigger. Keep in mind that the trigger when at neutral (untouched) does not sit at true zero of the pot (at one end of it's travel).

Full reverse might be considered a zero value. Neutral is probably somewhere around 50% with full forward is 100%. Looking like a 0 - 50 - 100 trigger. These triggers do not work on the principal (someone correct me if I am wrong) that neutral is true zero. That would look something like this -50 - 0 - 100. The pot will throw out a specific resistance for the trigger position in it's 0-100 position. If you only put a resistor in-line, you simply electronically offset the position. Neutral and all. What I'm getting at is this:

With the trigger at it's natural position (neutral), say for arguments sake, it's 50 ohms. Full reverse is 100 and full throttle is 0 ohms. If you bind and program the esc to those positions (No resistor), then all will program correctly and function normally. If you bind it normally then flip the switch to use the resistor, then you electronically offset the throttle to reverse partial throttle while the trigger is at neutral. Doesn't make for an easily controlled rig if you need to adjust the neutral point on the Tx.

Personally, I still think it's easier to get a transmitter with adjustable throttle curves and play around with it that way. Tx throttle curves actually CAN be flipped on the fly depending on Radio. Worst case, it would take about 7 seconds to adjust the curve appropriately. To each their own though.

You won't fry anything by simply dropping a resistor in line, but you will create some funky traits. You have the right idea for low speed throttle control, but will need to design it a little more before implementing.

Marcus

[DieCastoms]

Dragger, you bring out a very valid point that I hadn't thought of. Maybe if I crack the Tx open, I will take some measurements off that pot and find out of zero really is zero. Thanks for pointing that out!

DC