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Old Mar 04, 2011, 03:30 PM
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Question
AR6400T ESC amps total?

having just ordered a PZ Um Mosquito, i am wondering about the AR6400T rx, it says it has 'twin ESC' and that it can handle 'up to 2 amps continous', but is that EACH, or TOTAL? any body have any info on this?
or let me put ut this way, any body have the stock amp draw figures on stock PZ motor and props?

thanks, just wondering if i made a mistake, 'cuz i know i will crash and harvest.
nemo
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Old Mar 04, 2011, 06:37 PM
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its each. it has 2- 2 amp brushed ESCs
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Old Mar 05, 2011, 01:26 AM
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whew......good to know. i fly mostly brushed DC cuz at the scale i fly, BL is too much and too much weight. when it crashes, (and it eventually will) i might do that 72 scale c130.......
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Old Mar 05, 2011, 03:44 PM
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OK, the ESC's can handle 2 amps each. So the question is could the leads from the ESC be "ganged" together into one lead that would support a single 4 amp motor?
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Old Mar 05, 2011, 03:59 PM
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i don't think so.
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Old Mar 05, 2011, 04:59 PM
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Hmm....well...so much for that ...maybe.

Second question I forgot first time:

Could you run the AR6400T off just one ESC to just one 2 amp motor? That way you would only buy the AR6400T and not the regular AR6400 (they are the same price) . Because then if you wanted to use it in a twin you could, but if you didn't you could use it in your single motor job.
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Old Mar 05, 2011, 05:25 PM
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Originally Posted by alset View Post
Hmm....well...so much for that ...maybe.

Second question I forgot first time:

Could you run the AR6400T off just one ESC to just one 2 amp motor? That way you would only buy the AR6400T and not the regular AR6400 (they are the same price) . Because then if you wanted to use it in a twin you could, but if you didn't you could use it in your single motor job.
That would be interesting and quite possible, but it will have to be tested for sure. Somebody from HH said something about if one motor quit, the other stop automatically. So if it does monitor the load, and there's no load, it's quite possible that the ESC will not work with only one motor. I'm sure somebody will test that soon enough.
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Old Mar 05, 2011, 05:40 PM
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I bet you could run both ESC'c parallel to one motor.
TODD
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Old Mar 05, 2011, 05:50 PM
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akward flyer: why cant you gang the ESC? its brushed DC, so its just a pulsed 4.2V power to the motors, and unless there is a thrust vectoring mode on the thing, the pulses should be the same, or at least the same enough.
if the ESC is programmed for it, it may sence the crossover, but i can see why.

just wondering if you know something i (we?) don't, no disrespect intended.
nemo
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Old Mar 05, 2011, 05:58 PM
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oh not at all. jsut seems like it would be a pain in the butt when its easier to just use an external esc with a standard ar6400.
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Old Mar 05, 2011, 06:26 PM
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oh not at all. jsut seems like it would be a pain in the butt when its easier to just use an external esc with a standard ar6400.
Would be easier to connect the wires plus save $20 or so plus weight and real estate of an external ESC. And, you have the option of a twin.

P.S. Provo? Sorry about Davies. Didn't need him vs. the Pokes.
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Old Mar 05, 2011, 08:15 PM
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Originally Posted by nemoskull View Post
akward flyer: why cant you gang the ESC? its brushed DC, so its just a pulsed 4.2V power to the motors, and unless there is a thrust vectoring mode on the thing, the pulses should be the same, or at least the same enough.
Yikes, in my book, if I would design a dual brushed ESC, I would make it as efficient as possible. For that, I would avoid drawing too much current at any cost. So, both motors would not be driven at the same time until I exceed 50-50 pulses. Basically if we say the motors are taking 1amp each, let say both motors are running at half speed, instead of drawing 2amps, 50% of the time, I would have one on, while the other is off, so I would draw 1amp continuously. End result, if you use a cheap battery, there's less chance to hit the maximum C rating until you really go WOT... But that's just me! Since they use FET for outputs, they could likely be ganged together still, but sure enough, pulses would not be synchonized...
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Old Mar 06, 2011, 02:20 AM
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i wonder if it matters, most ESCs run at a few KHZ, that is pretty fast. as for designing one, if it were me, just add another mosfet and output and call it a dual. Brushed DC ESC is about as basic as you can get. any simpler and its called a light switch.

oh i see what you are saying about amp draw. the thing is mosfets are voltage controlled, not amp like the one BJT. in a BJT you put in 1ma, and get a factor of say 100 out. so 10mah in, 1000mah out. its pretty linear for most uses.
mosfets are controlled by voltage and don't have the problems of BJT. there is so little amps running thru them they can handle greater loads. AFAIK, the reason transistors burn up is not cuz the load, but the heat from switching the load on and off, the inefficiency of the thing creates heat.

but i may be wrong, so if i am, correct me.
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Old Mar 06, 2011, 06:09 AM
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Originally Posted by nemoskull View Post
i wonder if it matters, most ESCs run at a few KHZ, that is pretty fast. as for designing one, if it were me, just add another mosfet and output and call it a dual. Brushed DC ESC is about as basic as you can get. any simpler and its called a light switch.

oh i see what you are saying about amp draw. the thing is mosfets are voltage controlled, not amp like the one BJT. in a BJT you put in 1ma, and get a factor of say 100 out. so 10mah in, 1000mah out. its pretty linear for most uses.
mosfets are controlled by voltage and don't have the problems of BJT. there is so little amps running thru them they can handle greater loads. AFAIK, the reason transistors burn up is not cuz the load, but the heat from switching the load on and off, the inefficiency of the thing creates heat.

but i may be wrong, so if i am, correct me.
I could not correct you, heck, I never even looked at the output of a brushed ESC with a scope. I'm basically trusting what I heard here and there about how ESC works (particularly brushless!).

But just to make sure, my main concern in designing a dual brushed ESC would be to go easy on the battery most of the time. That's why I would avoid driving both motors at the same time until I hit 50% duty cycle. (It shoud allow us to use a lower C battery when we don't fly agressively) I do agree that design wise, the best is simply to run both FET from the same signal, but then, why not using simply one FET with way more current handling capacity instead of two. I know they wanted to be able to monitor each motor individually (so if one quit, they shut the other one), so there's more electronic involved here. Programming the MCU to drive both FETs individually is relatively easy. But who knows what they truly did. I guess I'll eventually have to dust off one of my scopes and find out by myself!

Can you believe that some lucky guys have jobs designing that stuff (or even flying them for that matter). I have the wrong job!
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Old Mar 06, 2011, 04:57 PM
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Hum be fun to use the AR6400T to power a v twin gearbox with twin motors using 8.5mm Solo Pro or Bravo SX motors with Didel spur gears with a (4:1 ratio) giving 90g of static thrust cnc milled out of Delrin. How cool would that be. Be cool if a gearbox like that existed
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