The motor generates more noise under heavy current than any other possible source. The receiver picks up that noise and can not decode it, so the decoder false triggers and the ESC shuts down the power to the motor. As the motor shuts down, it gets quiet and the process iterates. Thus it sounds as if the motor is cycling because it is. This can be checked on the ground. Do a range check with and without the motor running. If you lose more than 20% ground range when you turn on the motor, the system is being degraded by motor noise. The job is to squelch that noise. Interference to the receiver comes from the motor and motor leads. The motor generates the noise every time a brush crosses a commutator joint. The higher the current flow, the more intense the spark. If you peek through the cooling holes in the motor bell housing, you can see the sparks. Every spark projects a powerful burst of “white noise”, i.e., it covers all frequencies. It is about as bad as an arc welder. The power leads from a motor to the ESC act as an antenna. The longer they are, the more radiation they transmit. Steps to correct noise problem are listed below.

1. Be sure the motor is run in well to cut the amount of sparking that comes off the commutator. Poor quality motors may never become quiet enough to use in R/C, so avoid the temptation to use motors out of toys. If practical, run the motor in for 1/2 to one hour using no load and a 1.5 V D-size alkaline cell. Some folks even run the motor under water for around 1 to 3 minutes to wash away the dust from the brushes and help seat them. It is suggested that one rinse the motor in alcohol when through running to remove any residue that settles from the water inside the motor. It is bad practice to run a motor in the reverse direction once broken in. If you need to reverse a motor for some other application, repeat the run – in with the motor reversed.

2. Put a Shottky barrier diode across the terminals of the motor. It doesn’t hurt to have a diode at both the motor and the ESC. Be certain the banded end of the diode points to the plus wire from the speed control or you will wipe out the ESC. Solder two 0.01 to 0.05 uF, 50V ceramic, monolithic or polyester capacitor to the motor terminals; in parallel with the diode, one end of each cap to the motor terminals and the other end of each cap to the motor case (ground).

3. Keep the leads from the ESC to the motor as short as possible and twist the leads of all wires together to form as much self shielding as possible.

4. Arrange the receiver and antenna lead to be as far away as possible from a) the motor and power leads to the ESC and b) from battery to ESC.

5. Your receiver may not have enough tolerance to noise to be used in this application. If it is an FMA receiver, that is as good as it gets. If it is one of the inexpensive two channel AMs sold by some manufacturers, you may never get it to work in an electric application.

Will your car ESC handle my 13-turn “Belchfire Streak”, etc., etc. car/boat motor?

The answer is maybe! The biggest headache for every ESC manufacturer is that the number of turns on a motor used as a spec by motor manufacturers doesn’t mean much. The term refers to the number of turns of enameled wire around each segment of the motor armature. The wire size is not standardized and could be 12 gauge to 40 gauge. Resistance for 40 gauge is many multiples that for 12 gauge. You do have to remember that the load varies greatly during racing conditions. There are instances when the car sails over a hump and lights with the wheels spinning at a great rate. You can avoid this by throttling back while the car is airborne. A more accurate indicator of motor vs. ESC capacity is current. Can you safely determine the average or peak current of your system under load using an amp meter?

Do your ESC’s have reverse?

The MSC75FR M-SONIK SPORT RV 75; MSC130FR M-SONIK SPORT MAX 130; and MSC80FR car ESCs and the MSCM30FR M-SONIK MARINE PLUS 30 ESCs have reverse. Be aware that reverse is not allowed in racing. The first time a race steward sees you backing up your car, he will disqualify you.

Can your airplane ESC’s be restarted after cut-off?

Yes, on all except the SC5. When you hear the motor cut off, you may retard the throttle, then advance it again. The motor will restart and run until the battery voltage drops to cut-off again. Don’t do this too many times or you will eventually starve the radio and crash.

What is soft start?

If you use a geared motor, it is best to give the motor a very brief time to come up to speed when it is started; otherwise, the teeth on the gear drive may be stripped. Our first run of airplane ESC’s was optimized for gear drive. However, when we issued the first units for people to use for direct drive of props, we found that many liked to launch the airplane with the motor off and then turn it on in the air. The soft start was long enough that some had trouble getting the motor turned on before the ground jumped up to hit the model! Therefore, we decreased the “soft time” so that it is just enough to avoid stripping gears. End of problem.

Where should a fuse be installed?

In the power line from the ESC to the motor. Do not put a fuse in the battery lead as all power to the servos and receiver will be lost if the fuse burns out. NOTE: It is wise to put a fuse in-line between any motor and any ESC that equals the current rating of the ESC. Remember, an ESC makes a very expensive fuse and, if for any reason the motor shorts out or the rotor gets locked, your ESC is going to be toast!

Does the cathode (the banded end) of the Shottky rectifier go to the positive or negative output of the speed controller?

The cathode (the banded end) of the Shottky rectifier always goes toward the positive output of the speed controller. If the motor is running forward, the positive wire from the speed controller is then connected to the positive terminal of the motor and the negative wire to the negative terminal of the motor. To reverse direction of the motor, simply reverse the positive and negative wires coming from the speed controller but make certain the cathode of the rectifier stays with the positive output of the ESC, otherwise you will definitely burn the speed controller to a crisp!

Which FMA airplane ESC do I need to handle my motor?

It is important to know how much current the motor you use will demand. That is best determined using an amp meter in series with the motor or using the Whattmeter from Astroflight. Actual current consumption, in turn, depends on the size and type prop you use, how many cells are in the pack, and the throttle setting at which you run. The information that follows is oriented to the amount of current a motor can stand before it burns out; so these are maximum figures. Micro electric motors can handle up to about 500ma. Speed 280/300 motors can handle about 5 to 10 amps. Speed 400 motors handle up to 16 amps. 500/550/600& 680 motors can handle from 15 to 40 amps. Geared versions are at lower current levels unless the prop is large and high pitch. Rare earth magnet motors and motors larger than the Speed 600 may draw well over 50 amps. In very general terms, our mini5 is geared towards small indoor models. Our mini20 works well in most Speed 400 applications. Our mini30 is best with Speed 500 – 600 models. Anything larger than Speed 600 requires at least our mini50, but be careful here as 50 amps can get used up fast when the motors get exotic!

What is armature-locked current?

When the car hits the ground, the wheels come to a stop or spin as the car accelerates and/or the airplane prop hits the ground and stops, current can peak at over 100 amps. The resistance of an armature may be as low as 0.01 ohms. READ CAREFULLY: If you lock the armature in the motor with 7.2 V on it, the resulting current will be 7.2 / 0.01= 720amps! That will fry about any ESC. The next best thing is to put a fuse in line with the motor that protects the motor and the ESC until you know all is well, then you can take it out if you want. Next best is to start the car or airplane motor running slowly under simulated light load conditions and gradually increase the speed. Stop periodically and check the motor, the ESC, and the batteries to see that neither is overheating. Most of the ESC’s that come in for service were placed in an unknown car or airplane unit, and run full bore until the motor, the batteries, or the ESC expired!

Do your airplane ESC’s have low voltage cut-off?

All but the SC5. The larger ESCs have a voltage cut-off set for the value specified in the product spec for that ESC. The SC5 is a special case for use in small models where users want to operate below 5.2 volts for motor power. Since use of the SC5 is generally in very small models that have to be flown near the pilot so he can see the model, one can hear the motor start to slow and make a timely landing.

Do your ESC’s have a brake?

Yes, both the airplane and car ESC’s. The Marine ESCs do not. When the SC20/30/50 reach cut-off or you retard the throttle fully, the prop brake is applied. It is sufficient to stop folding props and to slow larger fixed props. The primary purpose is to stop folding props so they don’t bang up the model. Our car ESC’s may be programmed for ABS or standard braking. See the specs for the specific ESC.

Do I need a switch in the battery lead?

No. The tiny switch on the speed controls is leveraged many thousand times by the FET drive transistors. The switch controls the bias on the FET’s to turn them off completely and current flow to the motor is zero. As indicated in the manual, you may wish to install a switch in the battery line on the SC5 which does not ship with a switch for weight conscious applications. The M-SONIK SPORT ESC does not have a switch and you may choose to put a switch in line for it.

I was wondering if you could tell me the motor limit of this speed control. Thank you very much.

Current draw for a motor with the prop, battery, and/or gear drive chosen must not exceed the current limit of the particular ESC. It is impossible to know what the current draw for a motor is unless you measure it under the conditions under which it will operate. As an example, increasing the pitch and/or diameter of the propeller can double the current drain. A motor can be run with a wide range of voltage by increasing the number of cells. Motor manufacturers specify current draw as a function of voltage and torque. However, one generally has no way of measuring torque at the motor shaft. If you use a gear drive, not as much torque is demanded of the motor for the same voltage. However, prop RPM will be less and you can use a larger prop. There are two solutions to this issue: 1) Put a fuse in line with the motor (In the motor wire, not the battery wire. If you put it in the battery wire and it blows, you lose BEC power.) Please take note that an ESC is an awfully expensive fuse; yet, I see a lot of ESCs that have been used as fuses! An ESC (Or fuse) can be blown if your airplane lands in such a way that the prop is forcibly stopped and is not instantly at low throttle. 2) If you seriously need to know the current draw, use a Whatmeter from Astroflight or a decent ammeter to measure current draw for the combination of prop, gear drive, battery, and motor you wish to check. A variant of this question is received almost daily: What turns motor will your ESC handle? It is almost useless for motor sales companies (Particularly the car motors) to specify motors in terms of "Turns". A 12 turn motor can be of a wide range of wire size. Current drain goes up geometrically with wire size. It would be much better if those motors were specified in terms of current draw at a specific voltage and max permissible motor torque. Do remember that a motor with the rotor locked (Stopped) can draw several hundred amps and that will take out about any speed control as well as the motor very quickly.

Is there a way to by-pass the brake on the airborne ESCs?

No. The brake is a detriment to using the SC5 through SC50 with electric helicopters because the brake severely inhibits auto-rotation. It would be best to source an ESC that is designed specifically for electric helicopters.

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