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2nd ESC with DMD07 (leo 2 content), now with video desc... - 12/29/2012 4:10 AM   
gyrate


 

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Status: offline 		It's been ages since ive been around here. And it's time to try to once more, to resurrect this tank and turn it into something i like. I have never been happy with it for a variety of reasons but after several rebuilds and insane $ spent over the years on add on metal parts from all over the world, i have one last task to tackle, asides from turret/barrel stabalization that actually works. So really 2 tasks but i can ignore the turret and barrel for a few more decades......

Alright if that confused you, let me clear it up.

The problem

- DMD 07 is a piece of crap that suffers from pretty much 1980s throttle curve. ancient technology designed for AM receivers and nicad packs....
- the gearbox has a lot of neutral slop so changing from front to back or even after idle will result in it spinning up before any power is given to the wheels. that will result in a CRUNCH once the slop is wound up and power delivered. Result: jerky changes in speed or movement. You can only do so much with stick control to prevent those but it just never comes out right.

Both are inherent design flaws and cannot be corrected with the stock parts.

- removing the dmd altogether would create a lot more hassle but assume that right now, we want to keep it.

The proposition

Channel 1 is the throttle, channel 2 is the steering. Both channels are essentially an ESC for each of the motors (3rd one for the turret). Now, the issue is mainly with the throttle esc.

What if, we bypass that. Say unplug channel 1 from the dmd and use another ESC that you can program as you see fit. You can have exp curves within the esc itself, soft starts (cannot really be achieved with TX programming) and your model will no longer try to do a wheelie even with gear reduction installed. I haven't noticed much issues with the steering but the same principle could apply.

* generic rules apply; you would parallel power both escs and trim the power wire off the external esc since the dmd has a BEC built in.

The downside

You will likely lose the pivot turn ability by doing this one either 1 or 2 channels since the dmd overrides stick input and decides you want to do a pivot. so instead all you will have is a point turn.

Comments, thoughts?

I will try it as soon as i put the leo back together. Waiting some parts to come in

< Message edited by gyrate -- 1/1/2013 10:26 AM >

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 4:58 AM   
heavyaslead



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Status: offline 		Hello Gyrate

Comming down a bit hard on the 07 aren't you?

In a word, yes, what you propose will work.

The spin will still work as well as the spin can be independant of the drive or in tandem with the drive (true differential transmission).

If you are just looking for inertia and momentum control, a Turnigy chip in line with the motor drive may be all you need which can set the acceleration and deceleration curve rate.

As for technology, it works with the best 2.4GHz radios and Li-po batteries.

The tank is designed for scale 45mph, so controling that speed range from 0-45 is a bit difficult on a standard radio and does require some finess. Perhaps an RC car type radio would better suit your needs.


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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 5:44 AM   
gyrate


 

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Status: offline 		Well it deserves all im lashing out at it. Scary that i've had this thing for almost 10 years.

Im looking for more, including hill hold and hill descent control. You can say i have been spoiled by my recent builds and firing this fella up again made me cringe. I'll order some parts and get to it.

Do you still meet up? Site hasn't been updated since 2007 from what i see. I used to live around there

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 6:19 AM   
no12skyline


 

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Status: offline 		Would simply wiring one of Turnigy's servo speed regulators to the throttle channel achieve what you're looking for?

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 7:12 AM   
gyrate


 

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quote:

ORIGINAL: no12skyline

Would simply wiring one of Turnigy's servo speed regulators to the throttle channel achieve what you're looking for?

No. I can already do that with the transmitter.





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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 9:56 AM   
tomhugill


 

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Status: offline 		 I suppose it's all down to personal preference but I think the Leo 2 suffers least of all the tamiyas of the issues you describe. I hope I don't insult you here but have you switched it into low power mode on the dmd? When I first got mine I thought it was very hard to control until I found the power mode switch on the Dmd. With this turned to lower power the Leo became very manageable and one of my smoothest driving tanks.

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 12:48 PM   
YHR



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Status: offline 		With the separate ESC you will also lose the IR battle damage speed reduction.

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 6:33 PM   
heavyaslead



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quote:

ORIGINAL: gyrate

Well it deserves all im lashing out at it. Scary that i've had this thing for almost 10 years.

Im looking for more, including hill hold and hill descent control. You can say i have been spoiled by my recent builds and firing this fella up again made me cringe. I'll order some parts and get to it.

Do you still meet up? Site hasn't been updated since 2007 from what i see. I used to live around there


I would be interested to see how you will accomplish this task. If you don't like how the transmiter regulates acceleration then mechanical is the only way which will be quite difficult and probably require a shifting type transmission. I believe Jerry (who does 1/10 scale) has experience in shifting transmissions for tanks.

As fot the SEAD site, well the site's last major update was March 2012, probably should do more regular updates though.

Let me know if you are in the area and we could run some tanks!


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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 7:01 PM   
Panther G


 

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Status: offline 		Yeah I have never seen a Tamiya LEO act the way that is explained here so something more must not be being said.
The Leo board is the best that Tamiya makes. wish i could get one to work in every tank i own.


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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 8:10 PM   
tomhugill


 

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Status: offline 		sounds like its in hi power mode

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/29/2012 9:00 PM   
Lincs Winks Wayne



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Status: offline 		Hi:
I also hTve a Leo I just finished and it runs great. it is in the slow mode I have not tried the alternative.
I use a tactic TX and RX but had to reverse two of the plugs.
The self demonstration mode works well and tests the circuits and shows everyrhing except running the tracks.
I have one glitch which is, I have not been able to fire the machine gun but it is in the demonstration mode.

Good luck

Wayne


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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/30/2012 7:51 AM   
gyrate


 

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quote:

ORIGINAL: tomhugill

sounds like its in hi power mode



Of course it is. That's why im running gear reduction



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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/30/2012 7:53 AM   
gyrate


 

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quote:

ORIGINAL: Lincs Winks Wayne

Hi:
I also hTve a Leo I just finished and it runs great. it is in the slow mode I have not tried the alternative.
I use a tactic TX and RX but had to reverse two of the plugs.
The self demonstration mode works well and tests the circuits and shows everyrhing except running the tracks.
I have one glitch which is, I have not been able to fire the machine gun but it is in the demonstration mode.

Good luck

Wayne



After i went to the aurora 9 i never bothered even configuring that... with the vanilla 4wd fitaba it was no problem tho.

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/30/2012 7:59 AM   
gyrate


 

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quote:

ORIGINAL: Panther G

Yeah I have never seen a Tamiya LEO act the way that is explained here so something more must not be being said.
The Leo board is the best that Tamiya makes. wish i could get one to work in every tank i own.



Most people are blind and don't notice the fine little details; others have never ran a good ESC/radio and don't know any better. You are talking to somebody who removed the speaker 3 hours after the build was complete as i found it obnoxious and ill modulated (and needed the space for batteries). My stuff runs well, im no modeller so i invest in other areas.

Well i saved some money elsewhere so i bought a pretty decent g y r o (so i am told). Will try to get the turret to heading hold when it gets in. If the concept works i might move that one to the barrel and get a fancy g y r o for the turret. So it seems i am tackling both projects at the same time.



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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/30/2012 9:02 AM   
tomhugill


 

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Status: offline 		The high power mode isn't really suitable for anything other than high resistance surfaces like long grass and other off road areas. If your expecting fine control in hi power mode when running on hard surfaces or indoors then your being unrealistic. 

However I would love to see how you make a decent gyro work.



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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/30/2012 12:59 PM   
no12skyline


 

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Status: offline 		It sounds like you're doing a lot of stuff to that Leopard - how do you achieve gear reduction - by changing to smaller pinions? And are your twin battery packs wired in parallel, or can the T-07 cope with 14.4 volts in a series configuration? And given that you have removed the speaker, does that mean you don't have sound on the tank?

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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/31/2012 1:46 AM   
heavyaslead



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quote:

ORIGINAL: gyrate


quote:

ORIGINAL: tomhugill

sounds like its in hi power mode



Of course it is. That's why im running gear reduction



Let me clear a common misconception, the hi power mode ONLY affects the steering motor not the drive motor, switching this is irrelevant to what is desired for the drive motor.

Also adding a gear reduction does not clear acceleration and inertia issues, a simulation at best really, with the compromise of lossing top end speed which would be bad for a leo rated for 45mph scale. Unless, of course, a shifting transmission is added with the reduction.

A motor change-out would make more sense than a gear reduction - like a crawler motor, low T and you would have to watch the current draw.


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RE: 2nd ESC with DMD07 (leo 2 content), now with video... - 12/31/2012 10:14 AM   
tomhugill


 

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Status: offline 		 I'm not sure I agree with you there heavy, in high power mode the forward speed control becomes far more sensitive and difficult to control. It might not increase the top speed but changes the acceleration profile.

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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 10:26 AM   
gyrate


 

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quote:

ORIGINAL: tomhugill

 I'm not sure I agree with you there heavy, in high power mode the forward speed control becomes far more sensitive and difficult to control. It might not increase the top speed but changes the acceleration profile.


you know i think i am going insane here over this thing so i made a video. yes barrel is installed that way for a reason, pay no mind.

judge for yourselves folks. this cannot be normal! granted i haven't run the thing in like 2 years but......... its been stored in my office and everything from there works fine after even longer hibernation

http://www.youtube.com/watch?v=40fyhrgxnso

make sure to read the entire video description!

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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 10:31 AM   
gyrate


 

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quote:

ORIGINAL: heavyaslead


quote:

ORIGINAL: gyrate


quote:

ORIGINAL: tomhugill

sounds like its in hi power mode



Of course it is. That's why im running gear reduction



Let me clear a common misconception, the hi power mode ONLY affects the steering motor not the drive motor, switching this is irrelevant to what is desired for the drive motor.

Also adding a gear reduction does not clear acceleration and inertia issues, a simulation at best really, with the compromise of lossing top end speed which would be bad for a leo rated for 45mph scale. Unless, of course, a shifting transmission is added with the reduction.

A motor change-out would make more sense than a gear reduction - like a crawler motor, low T and you would have to watch the current draw.


dmd7 can only handle 20amps per motor (or was it 40? either way weak). a good 55t can suck down 50 continious with over 80 peak. granted the gearbox in this model will not allow for that much draw but just saying.

anyway, watch video. might clear some things up.



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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 11:12 AM   
tomhugill


 

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Status: offline 		Ill be honest from that video all I see is you mashing the sticks making no attempt to drive it smoothly. The leo dmd has a slight delay going from forward to backward, I assume to protect the TUs. With the turret Ive had issues where if a smash it upto full throttle then nothing happens, but thats the way ive setup the limits on my radio so I can get the mg and main gun to fire without messing with the trims. Ill put a video of my leo going for comparison.  

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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 11:37 AM   
tomhugill


 

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Status: offline 		Rewatched the vid and noticed that you seem to be hitting the deadzone, now I'm not sure if this is controller based or in built to the Dmd. It does give a tiny area where your controller doesn't do anything which helps stop jack rabbit starts. Just charging my tx now vid to follow.



There you go!


< Message edited by tomhugill -- 1/1/2013 12:06 PM >

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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 4:37 PM   
CCC2012


 

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Status: offline 		damn.....so its normal for that slight jerk movement?>i am in process of building my leo and this has caught my attention....does the DMD 7 go bad?>

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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 4:54 PM   
tomhugill


 

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Status: offline 		 Which vid are you referring to? The high power modes harder to get a completely smooth acceleration from standing, but in situations where you'll be using hi power mode then it's probably not and issue.

What the op is referring to is not normal for the Dmd 07.

@OP you could have a faulty Dmd, well they have a lifetime warranty so they'll sort it for you for free.

As regards being jerky and ripping up tus, you say you've added 2:1 fear reduction here, well that's double the torque going through transmission and given your very very jerky stick movement no surprise your having issues. If your tried to drive your car like this it wouldn't last long........


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RE: 2nd ESC with DMD07 (leo 2 content), now with video ... - 1/1/2013 5:53 PM   
gorehound


 

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Status: offline 		Hi

I stuck a 55 turn puller motor designed for the Tamiya Trucks in place of the stock drive motor in my one. Left the pivot motor stock. Also added a Turnigy Servo regulator in with just a hint of delay in it and found the improvements great. No jerky movement and smooth acceleration and deceleration.

I also added the turnigy receiver controlled on/off switch to the motor power to a spare channel on the transmitter so I could disable drive and give it some revs - just for effect.

cheers
Gorehound

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