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Old May 05, 2001, 10:23 AM
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Attack in my Garage - Futaba Rx/ESC Question

I recently discovered my "Attack 4 AM" (FP-T4NBL) in storage after it had been missing for eight years.

It originally came as a set with two micro servos and an integrated Rx/ESC with BEC (# MCR-4A). I've lost the manual. I'm most interested in the specifications of the speed controller and its BEC unit. Anybody know...
1) What is the max continuous amperage rating? Peak?
2) How many battery cells can I use? 6 to 7? 6 to 8?
3) Does it have auto motor cut-off at low battery voltage?
4) How do I set the throttle end-point? Is it the screw that's visible from the top? If so, technique?

Thanks in advance for any help you can give.
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Old May 05, 2001, 10:47 AM
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Hi Dave

I seem to remember that it was a low frequencey (Frame rate) speed control that did have BEC and was rated for 05 ferrite can motors of the time. as far as auto cutoff...?
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Old May 05, 2001, 03:17 PM
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Santa Rosa, Northern CA, USA
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It has been a long time since I had one, but I think 7 cells was the max suggested. The Esc part will not handle to many amps, maybe 20?, it is a "frame rate" so use it a at full throttle, not partial for best results, does have a cutoff(I think), but no brake.

The screw at the top is the throttle adjust.

Should be fine for Speed 400 use, but the new stuff is much better.

Dave
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Old May 05, 2001, 03:32 PM
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I still have an operational MCR-4A in a Teddy.

It is definitely frame rate (fairly soft though) and stops completely (won't restart) when the voltage from the motor pack voltage gets low. It has an arming switch and the adjustment screw sets the idle point.

Not a sophisticated unit by today's standards, but fine for lower current direct drive applications like a Teddy.

Here are the specs exactly as written in the Instruction Manual for the FP-4NBL TX:

AMP
Operating System:Idle to maximum speed, no brake, idle point trimmer
Voltage: 6.0 to 8.4V
Continuous Maximum Current: 100A (!)
Momentary Maximum Current: 450A (!!)
Resistance Loss: 0.01 Ohm

How did they arrive at those current ratings??? 8) I would divide them by 4 or so...

Rob
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Old May 05, 2001, 08:17 PM
Older but not wiser
Richland, MI, USA
Joined Jan 2001
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I use mine with a geared 600 size motor, it needs some air cooling so it won't cut out. 7 cells is max for it.
I also use the TX on a bigger plane with a geared Astro 25G and 16 cells. A new am RX costs about $70.

HRH
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Old May 06, 2001, 12:02 AM
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Thanks to all for the info...

I know it isn't Hi-Tech, doesn't do anything but reverse the servos, but I sure was happy to find it the other day. Paid $220+ for it 10 years ago and I think I had about 20 flights on it - flew in my first EP, the PT-Electric, which still hangs pristine in the rafters back in the States.

Now! What am I gonna build for it?? Heee.
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Old May 06, 2001, 12:50 AM
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Rhode Island
Joined Oct 2000
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Quote:
Originally posted by rscamp:

Here are the specs exactly as written in the Instruction Manual for the FP-4NBL TX:

AMP
Operating System:Idle to maximum speed, no brake, idle point trimmer
Voltage: 6.0 to 8.4V
Continuous Maximum Current: 100A (!)
Momentary Maximum Current: 450A (!!)
Resistance Loss: 0.01 Ohm

How did they arrive at those current ratings??? 8) I would divide them by 4 or so...

Rob
Hmm, 100A and 0.01 ohm internal resistance? That works out to 100 watts! Sure sounds funny to me.
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Old May 06, 2001, 11:24 AM
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Those are metric watts. Divide by 25.4..
At 100 amps, the wiring needed for the load would weigh more than a Buick!
The MCR-4A is a handy receiver.. I have two, and use them occassionally.. one has a slightly melted case from abuse..
A bit larger and heavier than is fashionable now.. after a mere 10 years.!
.
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Old May 06, 2001, 11:39 AM
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Quote:
Originally posted by BobK:
Hmm, 100A and 0.01 ohm internal resistance? That works out to 100 watts! Sure sounds funny to me.
Sure does. The controller has some sort of automatic shutoff if the current is too high. Maybe they were sneaky and took this into account. I have some tiny little speakers like this. Rated at 100W continuous (and they mean it), but they have a built in protection circuit...

Rob

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Old May 06, 2001, 11:52 AM
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Dundas, ON Canada
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Quote:
Originally posted by Sparky Paul:
Those are metric watts. Divide by 25.4..
Hey Sparky.

You can't fool me. We buy gas in litres and post speed limits in KPH up here.

I'm pretty sure metric watts are only used by clever scientists in long white lab coats and thick glasses doing research on perpetual motion...

Rob
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