My wife surprised me with a Futaba 6EX for Christmas. I had mentioned a radio, but I really expected to get gift card for somewhere. But she researched it and decided the Futaba was the best in the field. Good work, I say. But, now I plan to build an electric plane and I need a better understanding of ESC technology. Let's see how much of it I have right. I understand what the esc does and how, it's the details I'm fuzzy on. The best I can gather from the reading I've done, the motor can be a different voltage from the radio because the motor is controlled by a totally seperate system. The esc can have a BEC circuit for radio power. Here's where I get fuzzy. My Futaba receiver is 4.8v. Is this standard? Are there different receiver voltages and do I need to consider this when I buy an esc?? And speaking of radio, the radio I have is pretty sizeable. Are there mini or micro rx's compatible with the 6ex? Any suggestions? Is it better to dance with the one that brung ya, or is mixing and matching the best of each manufacturer a better idea? By the way, I have an extensive technological background, but I am essentially totally new to RC.
I suppose that's enough for a start, I'll get into the plane I'm building and all that probably on another forum. Thanks in advance for your input.

1) The Futaba receiver can be run on 4.8 to 6.0 Volts, so that translates into a 4 or a 5-cell NiCd/NimH battery. Some ESCs can be set to supply 6V to the receiver (and servos) but most of them just supply 4.8V.
2) There are LOTS of mini RX's available. If you buy one, be sure it is a negative shift receiver (which matches Futaba's frequency shifting scheme) or get one of the newer ones that can "autodetect" the shift of your TX. Castle BERG receivers are pretty good. For park flyers a single-conversion RX is adequate, but you'll probably want to get a dual-conversion RX for any gas-powered or sailplane flying - they generally have a longer range.
3) The receiver "doesn't care" what kind of TX is sending a signal, as long as it's on the right frequency and properly shifted. The transmitter "doesn't care" what receiver (if any) is getting the signal, as long as the antenna is on the transmitter.

Think of the ESC as a replacement for the throttle servo.

Now, in the case of a nitro or gas plane, the throttle SERVO is where the electricity is needed, and the engine takes its power from the ignition. So your batteries just drive the servos and receiver, none of which draw massive amounts of current.

In an electric plane, the ESC performs the same function of the throttle servo, which is control, but it also PROVIDES all the current.

The ESC connects to the motor, a battery (which drives the motor and the internal electronics), and the receiver, which controls the ESC.

So the simplest (electrically speaking) setup would be to have the ESC wired to the motor, a big fat battery, and then plugged into the receiver which is being powered (into its "batt" connector) from a completely separate battery.

Now, thats simple but but practical, since you now have 2 batteries in your plane or car.

The receiver cant power the ESC since it cant handle the high currents, so it makes sense to make the ESC power the receiver in addition to taking commands from it. Thats what the BEC does, it allows the receiver to be powered by the ESC.

To add to the above, an important thing to keep in mind when buying a ESC is that it is rated for more than the amp draw of the motor you choose to use, this is determined by and relitive to your choice of prop and battery size
example a 1750 KV motor running on a 3S lipo turning a 7X4 prop will draw about 16 amps at WOT, in this set up a 18 amp ESC will work but it's right at it's limit
now drop to a 6X3 prop and your now down to around 12 amps
same set up on a 2S and now your down to 4 to 6 amps

now the only reason you would use a seperate batt pack for your servo's and RX is if you are running more servo's than the ESC can handle or if you have a large amp ESC that doesn't have a BEC, or if your running multiple motors, more than 2 and a flight pack would be advised

I found that at first it was easier to buy motor ESC combo's that would do what I needed untill I learned enough to just start putting this with that

I hope this helps

Thanks for the input folks. I'm sure I'll be back with more questions.

You may find this discussion helpful.
http://www.wattflyer.com/forums/showthread.php?t=18521

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