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Mar 16, 2012, 10:09 AM
Registered User
Gravman's Avatar
Question

Motor control unit for Dumas 1/20th PT


I know this is a long shot but I thought I would ask the question. Does anyone make a magic box that will allow three motors and three speed controls to be used in such a way as to run just the center motor at low speed. Then as you apply more power the two outboard motors kick in. I know you could do it with multi channel radios but I would like it to work with just a two channel set. Like I said I doubt there is such a thing to just buy and plug in but you never know.

Grav
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Mar 16, 2012, 10:56 AM
Mmm, tugs...
patmat2350's Avatar
That reminds me, I owe you a response Grav!

How are you with wires and soldering irons?
Mar 16, 2012, 11:28 AM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Maybe you could apply the Action-Electronics motor mixer to do that for you.

http://www.action-electronics.co.uk/mixers.php
Mar 16, 2012, 01:10 PM
Mmm, tugs...
patmat2350's Avatar
It does tank steering, but not the third motor ramp up like my PT's controller.
Grav- I can provide same, programmed, but any needed tweaks will be difficult!
Mar 16, 2012, 03:21 PM
Registered User
It just needs programmable ESCs - many need to be set up, the centre one just needs to be set so that it has a narrow dead band, full speed at a low stick setting, and the ability to carry on giving full speed when getting a signal outside its programmed limits. That lets Mtroniks out.
Mar 16, 2012, 04:30 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Here the Action-Electronic's mixer instructions show that it can run three motors, on a two channel receiver.

Bottom of the page at Harbor Models...
http://www.harbormodels.com/site08/m...d_controls.htm

Mar 16, 2012, 04:35 PM
Mmm, tugs...
patmat2350's Avatar
Yes, but it won't ramp up the middle one to 50%, THEN bring in the wing motors. I use this to cruise on one motor... With a 2ch radio. I tried the Action unit, tossed it, strange and uncustomizable transition between straight and turning.
Mar 16, 2012, 05:18 PM
Registered User
The Seer's Avatar
OK with all that has been said about the motor mixer P40c I have one question.
I am interested in your system how much for one already built and ready to install?
the reason for this question is simple there are those of us who are not programmer's and would just like to install your unit, that leads to the next question Do you sell the mixer you designed?

thanks again
Mar 16, 2012, 05:57 PM
Mmm, tugs...
patmat2350's Avatar
Aye, there's the rub... the unit I used for my controller is now obsolete, no longer produced... shame, because it was handy for plugging in to 12v and multiple ESCs.
I could replicate it with newer hardware, but it will require lots of fiddly time consuming assembly of bits and wires, making it unreasonable for me to produce for the 1 or 2 folks who'd like one.
Grav, never mind...
Mar 16, 2012, 06:54 PM
Registered User
GRAVEMAN- If you have a speed control that will handle the current for all three motors, you can make a system to do what you want with a servo Y harness and a servo to trip a micro switch ( 25 amp rating) when the throttles are at half speed forward. The micro switch would have a positive lead tapped from the speed control output to a split Y to both out side motors. The out side motors would start running at half speed when the switch is tripped and then run up with speed with the center motor.

Any thing less than half throttle forward you would be running only on the center motor and you will only have reverse on the center motor.
Mar 16, 2012, 08:32 PM
Registered User
Gravman's Avatar
Thanks guys I will consider options for trying this. I will see what I can figure out.
Mar 17, 2012, 05:59 AM
Ragbagger
Ragbagger's Avatar

Motor Controls ion Dumas 1/20th PT


It would seem soooo easy to just go back 30 years in technology and use one of the many extra channels on the radio and servo hooked to an old manual switch to cut the wing engines in and out.

simple, effective, and cheap
Mar 17, 2012, 12:00 PM
Registered User
The Seer's Avatar
Hi Patmat

Just out of curiosity what was the Max running time on your set up for the PT 41.

Thanks
Mar 17, 2012, 12:40 PM
Mmm, tugs...
patmat2350's Avatar
How long a time can you drive your car? It all depends!


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