Glossary

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Welcome to the Glossary section of Novak Electronics' Web Site.
The following is a quick reference to terms related to Novak products.

TABLE OF CONTENTS

A-C

ABEC: Precision ball bearings are manufactured to standards established by the Annular Bearing Engineers Committee (ABEC). All bearing used in Novak Brushless motors conform to ABEC 5 standard.

Adjacent Channel Rejection: The interference caused by a transmitter operating on an adjacent channel. For example if you are on channel 70, then channel 69 and 71 would be the adjacent channels.

Adjacent Channel Selectivity: The ability of a receiver to reject signals on channels adjacent to that of the desired channel.

Anti-Glitch Circuitry: An exclusive feature from Novak that rejects signals read by the speed control from the receiver which are caused by radio interference. (Same as Digital Anti-Glitch Circuitry.)

BEC: The Abbreviation for Battery Elimination Circuitry. The BEC is a built-in voltage regulator that supplies a constant voltage to the receiver and servo. Novak's GTB ESC has a 3 amp very low voltage dropout BEC. There are two type of BECs: Linear and switching type. Most ESC use linear type. These are designed to handle a maximum of 8-9 volts input. The switching type can handle a much higher input voltage, but they do produce electrical noise that sometimes interferes with the radio system.

Brake PWM Frequency:The frequency at which the duty cycle information is being sent from the speed control to the motor for braking. It also controls the deceleration characteristics of your vehicle with respect to trigger movement in the Full Brake direction. Brake PWM Frequency is measured in Hertz (Hz).

Bonded Magnet Rotor: A recent development in magnetic materials is the high-energy polymer bonded magnet. Magnetic powder, namely neodymium-iron-boron (NdFeB), is blended with polymer and injection molded to form complex shapes. A maximum magnetic energy level of 12 MGOe is attainable with bonded magnets. The biggest shortcoming of bonded magnets is the low operating temperatures.

Braking Current: The amount of force or power the brake circuit can deliver; usually the more the better. ESC's with higher braking currents can provide better braking without fading.

Brushless Motor: Novak brushless dc motors have a rotor with permanent magnets, and a stator with windings. It is essentially a dc motor turned inside out. The brushes and commutator have been eliminated and the windings are connected to the control electronics. The control electronics replace the function of the commutator and energize the proper windings or the Phase. Winding are energized in a pattern that rotates around the stator. The energized stator winding leads the rotor magnet, and switches just as the rotor aligns with the stator. There are no sparks and no voltage drops across the brushes and the commutator. Also because the winding is on the outside, heat generated in the winding has path of low resistance out to the case. Novak brushless motors are far more efficient then typical brush motors used in RC. The brushes of a dc motor have several limitations: brush life, brush residue, maximum speed, and electrical noise. BLDC motors are potentially cleaner, faster, more efficient, less noisy and more reliable. However, BLDC motors require a special ESC.

Continuous Current: The MOSFET's ability to handle current over a continuous period.

Current Limiter: This feature, found in Novak's Racer-EX and Tempest ESCs, allows the user the ability to adjust the maximum amount of current to be passed through the ESC upon acceleration. The current limiter functions similarly to an electronic slipper clutch.

Dead Band: The space between Minimum Brake and Minimum Drive, with Neutral located at the center of this space.

Digital Anti-Glitch Circuitry: An exclusive feature from Novak that rejects signals read by the speed control from the receiver that are caused by radio interference.

Digital Peak Detection: Measures the battery voltage and stores that information as a digital binary number. This number does not change due to temperature or drift over time. An analog peak circuit stores that same voltage information in a capacitor, which can lose information as time passes (measured in seconds), and is greatly affected by temperature. Digital Peak Detection is the only way to achieve an accurate peak value.

Diode: A two-terminal semiconductor device, that acts as a one-way valve which allows the electrical current to only flow in one direction. Typically a Silicon diode has a forward voltage drop of approximately 0.7 to 1.0 volt across the two terminals at full load.

Discrete Steps: The smallest motion change that can be distinguished from neutral to full throttle. The more steps a speed control uses to accelerate (or decelerate), the smoother the driving will be. Novak's GTB and GTX speed controls have up 1300 steps to create the smoothest trigger response available.

Drag Brake: Turns the deadband area into brakes -- eliminating the time, or dead space, to travel from brakes to throttle.

Drag Brake Frequency: The frequency at which the duty cycle information is being sent from the GTB or GTX to the motor for Drag Braking during neutral/deadband. 10 different settings are available. Drag Brake Frequency also controls the deceleration characteristics of the vehicle with Drag Brake during neutral/deadband. Drag Brake Frequency is measured in Hertz (Hz).

Drive PWM Frequency: The frequency at which the duty cycle information is being sent from the speed control to the motor during forward drive (How many times-per-second the motor is being cycled on and off to control its speed). It also controls the acceleration characteristics of your vehicle with respect to trigger movement in the Full Throttle direction. Drive PWM Frequency is measured in Hertz (Hz).

DSC: The abbreviation for Direct Servo Control. A DSC harness is connected between the transmitter and receiver and can be used to adjust system components such as servos, linkages and the ESC without transmitting a radio signal.

Dual-Level Thermal Protection (Also referred to as Thermal Overload Protection): A built-in sensor which shuts down the MOSFET(s) when its temperature exceeds a preset level. This circuitry provides protection from overloads. Dual-level protection cuts the throttle in half when the ESC temperature reaches unsafe levels. If the temperature continues to climb, it will shut down.

E-I

Electromagnetic Interference (EMI): The interference, generally at radio frequencies, that is generated within the system (in this case the car), as contrasted to RF interference coming from sources outside the system.

Electronic Speed Control (ESC): A type of speed control which regulates the speed by PWM. This method of control is highly efficient and results in smooth, proportional throttle control, greater speed and longer run times.

High Frequency ESCs: High frequency ESCs normally use 1,000-23,400 Hertz PWM to control the motor.

High-Frequency Operation: All Novak speed controls are true digital high-frequency controllers. A digital PWM frequency provides smooth, linear control of your model. Benefits include longer run times and extended motor life.

Input Voltage: The minimum or maximum voltage in which the ESC is designed to operate. To obtain Input Voltage, multiply the number of cells by 1.2 volts. For example, when we specify that the ESC will work from 4-10 cells, the input voltage is 4.8 to 12.0 volts.

L-N

Linear Charging: In the chargers Linear Mode, constant current is maintained by varying the applied voltage to the battery to maintain the user-set current value.

Low Frequency ESCs: Low frequency ESCs normally use 60 Hertz PWM to control the motor.

Low Voltage Operation: Novak ESC such as GTB is designed for low voltage operation. The brain of the ESC is a high performance micro controller that is supplied constant power even if the supply voltage goes down to 2 volts. This prevents erratic operation of microcontroller due to voltage fluctuations.

Mechanical Speed Control: A type of speed control which regulates the speed by lowering the voltage to the motor through a resistor; an inefficient technique. Mechanical speed controls also require a servo for operation and offers only 2-3 steps of control.

Minimum Brake: The amount of brake applied with the first pulse of transmitter throttle information.

Minimum Brake Adjustment: The ability to adjust the starting amount of the brakes. With the Novak GTB or GTX Programmable speed controls, the minimum brake amount is adjustable from 0-75%. 10 different settings available.

Minimum Drive: The amount of drive applied with the first pulse of transmitter throttle information.

MOSFET: The abbreviation for Metal Oxide Semiconductor Field Effect Transistor. A MOSFET is a voltage controlled power device that is capable of handling large electrical current flow. This type of transistor allows Novak to design small speed controllers capable of handling the demanding requirements of R/C racing.

MOTOR LIMIT: A guideline for the lowest recommended number of turns that can be used with a particular ESC. The turns in a motor are the number of windings on the armature of the motor. The lower the number of turns, the lower the resistance of the motor. This lowered resistance results in a potentially higher current draw, which can cause the ESC to run hotter. Our motor limits are based on using a single motor in 1/10th scale vehicle, with 6-cells, and a gear ratio of 4:1 or higher. Your gearing, driving style, number of cells, tire size, ambient temperature, vehicle weight, and the amount of air flow over the heat sinks will effect the amount of heat build-up in the ESC, motor, and batteries. If you use a motor with fewer than the recommended minimum number of turns, you will need to monitor the ESC for excessive heat. If you use more than 6-cells you will need to increase the number of turns on the motor to prevent damage to your ESC. For dual motor recommendations, see the "Wire Dual Motors" page in our "How To..." section.

MOTOR SENSORS: Novak brushless motor use three Hall Effect sensors that provide the exact position of the rotor to the ESC. These sensors are located in the rear end bell and positioned 120 degrees apart. Novak uses a specially designed test setup to calibrate the location of the sensor with respect to the winding. Motor timing is measured on a digital oscilloscope to guarantee high accuracy. All motors' timing are spec'd to +/- 2 degree of the required timing.

Narrow Band: If a receiver is operating on channel 68 (75.550 MHz), information sent to this receiver by the transmitter takes up 3 KHz (0.003 MHz) on either side of the frequency. This means all information required to control the R/C model is between 75.547 and 75.553 MHz. A narrow band receiver would only allow the selected channel plus 3 KHz on either side of the center frequency to pass, which means that other out-of-band information is not allowed to pass. A non-narrow band receiver would allow many out-of-band signals to pass through, causing interference.

Novak Ni-MH2: A charging mode used exclusively by Novak for charging Ni-MH battery packs. It utilizes an advanced charging algorithm which was developed by Novak Engineers for highly accurate charging of Ni-MH cells. The high accuracy of the Ni-MH2 mode prevents false-peaking as well as overcharging (which can overheat the cells) ensuring a fully charged battery pack each and every time.

O-P

On-Resistance: The restriction an ESC offers to the flow of the current to the motor at full speed. The lower the on-resistance, the higher the efficiency (performance) of the ESC. We measure the ESC's on-resistance based on the transistor's rating at 25 degrees Celsius junction temperature. For example, Novak's GTB speed control uses 18 very RDS on Mosfet (6 per phase) that are rated by the manufacturer at 0.0012 ohms each.

One-Touch Set-Up: A Novak first! Our One-Touch system allows the user to automatically adjust the speed control to the transmitter with the touch of a button. This system eliminates the need for manual transmitter adjustments using the neutral and high speed pots. In our GTB Brushless ESC’s, the One-Touch button is also used to select a driving profile and change individual function setting.

Peak Detection: When batteries reach a fully charged condition, the pack's voltage begins to drop. A charger that uses peak-detection senses this drop in voltage and changes from a high rate of charge to a trickle charge (or off in the pulse mode). Digital peak detection is more accurate than analog peak detection.

Polar Drive Circuitry: A Novak exclusive feature which allows the circuitry to stay cool while enabling the speed control to handle higher powered motors. The results include a smoother performance, increased acceleration, longer run time and increased radio system range. More Info

Profile: A set of design parameters that determine the functionality of the speed control. These parameters address functions such as how wide the deadband is, what percentage of full throttle is applied with the first pulse of transmitter information, and what the drive and brake frequencies are. Most ESCs have one profile. Novak's GTB speed control include 6 profiles, all of which are user-customizable profile. Profiles are selected using the One-Touch button.

Proportional Control: This means that the speed of the car responds identically to throttle movement on the transmitter.

Pulse Charging: In the charger's Pulse Mode, voltage applied to the battery is 100% of the source voltage. The user-set current value is obtained by the on/off time of the voltage applied (PWM). For example, if 100% voltage causes 10 amps to flow into the battery, to obtain a 1 amp charge rate, 10% duty cycle is used. This means for any given pulse, the on time is 10% and the off time is 90%.

PWM: The abbreviation for Pulse-Width Modulation. ESCs pulse current to the motor in an ON-OFF manner. Changing the ratio of the ON time to the OFF time changes the speed of the motor. For example, at 80% speed, the current pulse is on 80% of the time and off 20% of the time. This cycle happens 60 times-per-second for low-frequency ESCs, and approximately 2,500 times-per-second in the Novak high-frequency ESCs.

R-S

Radio Frequency Interference (RFI): Interference from outside the system or systems, as contrasted to Electromagnetic Interference (EMI ), which is generated inside the system.

Radio Priority Circuitry: When battery power is running low, this circuitry makes sure that power keeps being sent to the receiver. This maintains control of the model, even after the batteries have discharged.

Rated Current: Rated current, or peak current, is the MOSFET's ability to handle high current surges for a very short duration (1-2 microseconds).

Regenerative Power: While braking, energy generated by the motor is fed back through the ESC into the battery pack – this can only be accomplished when the power MOSFETs are turned ON and OFF at a very fast rate, such as in our high frequency ESCs. This regenerative power provides increased battery life.

Reverse Disable: A feature in all currently manufactured Novak Reversible Electronic Speed Controls which enables a driver to turn off or "lock out" reverse for racing situations. When reverse is disabled, the ESC operates as a forward-only speed control with brakes. Reverse Disabling is turned on and off using the One-Touch Set-Up button.

Reverse Pulse Charging: A charging mode used in the Millennium Pro Battery Management System, which testing has shown helps improve the performance of older NiCd battery packs. When cells are charged in Reverse Pulse Mode, the charging process is interrupted once every second and a 6 amp discharge (Reverse Pulse) is applied to the cells. The length of time in which the discharge is applied is user selectable from 5 to 20 msec. After the pulse is applied, normal charging resumes for one second, at which time the cycle repeats. Currently, Reverse Pulse Charging is intended for use with NiCd cells and is not recommended for use with NiMH Cells.

Reverse Time Delay: A feature which allows a reversible speed control to go into a fully proportional brake mode before going into reverse. For the Rooster, the preset time is 3 seconds. The 610-HRV features an adjustable time delay from 0-3 seconds.

Reverse Voltage: When the power source (battery pack) is connected backwards to the ESC's red and black wires.

RF: The abbreviation for Radio Frequency.

Schottky Diode: (pronounced Shot-Key) A special type of high-speed diode that has a very low forward-voltage drop. This means it offers very little resistance to the flow of current in one direction. The average Schottky diode forward-voltage drop is typically 0.30 to 0.45 volts under full load. MORE INFO

Sintered Rotors: Sintered magnets are a type of ceramic composed of compressed Neodymium-Iron-Boron powder. Sintering involves the compaction of fine alloy powder in a die, and then fusing the powder into a solid material with heat. While the sintered magnets are solid, their physical properties are more similar to a ceramic, and are easily broken and chipped. Sintered NdFeB magnets are generally plated or coated with Nickel-Copper-Nickel plating to prevent corrosion. Nickel-Copper-Nickel plating has excellent corrosion resistance and durability as well as providing a clean and shiny appearance. Magnets used in Novak motors are high-energy 30 MGOe, and high temperature materials.

Smart Arming: A safety feature exclusively from Novak that prohibits the propeller from spinning until a valid "no throttle" signal is present for at least two seconds. This feature is unique to the Arrow Airplane ESC.

Smart Braking: A feature that allows a reversible speed control to go into a fully proportional brake mode before going into reverse. The user simply brings the throttle back to Neutral and then the Brake portion of the trigger becomes reverse. The feature is in all currently manufactured Novak Reversible Electronic Speed Controls, and is designed to help reduce wear and tear on the model's drive train, and also reduce the amount of heat build up in the ESC.

\Solid State Reverse Voltage Protection (RVP): Our proprietary reverse voltage protection circuit uses a MOSFET to control the flow of current to the brake and the ESC's control circuitry. This circuit shuts off the flow of current in case reverse voltage is applied, thus preventing any damage to the ESC. Absence of any mechanical fuse means no fuses to change or repair.

Solder Posts: Allows the user to replace the power wires on the speed control for custom installations. Our solder posts are made from a high-conductive copper metal allowing for a low resistance connection. The wires can be soldered to the solder posts in any direction for ease of installation.

T-Z

Thermal Overload Protection (Also referred to as Thermal Protection): Thermal Overload Protection is a built-in sensor which shuts down the MOSFET(s) when its temperature exceeds a preset level. This circuitry provides protection from overloads. Dual-level protection cuts the throttle in half when the ESC temperature reaches unsafe levels. If the temperature continues to climb, it will shut down.

Throttle Priority Circuit: All Novak speed controllers come equipped with this circuitry. The circuit monitors the battery voltage and prevents it from going below 3.3 volts by controlling the power to the motor. This function allows the receiver and servo to operate properly during heavy load condition or at the end of battery charge.

Third-Order Intermodulation Point (3IM): Describes the non-linearities of the receiver's mixer stage. This means that if a transmitter is operating on a given channel, transmitters that are 20 KHz and 40 KHz (0.020 and 0.040 MHz) away will cause 3IM-related interference. For example, if you are using channel 70 (75.590 MHz) and two other drivers are on channel 69 (75.570 MHz) and channel 68 (75.550 MHz), the output of channel's 69 and 68 will mix inside the receiver's mixer and generate interference on channel 70. Receivers that have a high 3IM (such as Novak receivers) can withstand a high level of 3IM-related interference.

Trickle Charging: A reduced rate of charge usually described as the battery capacity divided by 10. This small amount of trickle current allows cells to equalize after their fast charge cycle has been completed. Trickle charging tends to slightly suppress the voltage of the battery pack, and is generally not used for racing.

Voltage Threshold: A user selectable feature used in the Millennium Pro Battery Management System whereby the user can set the amount of voltage change that is necessary in order for the charger to detect a "Peak" in a battery pack. As cells charge, the pack voltage will increase until fully charged. At this time, the voltage on the pack will start to drop. When the voltage drops by the amount set in the Voltage Threshold setting, the charger detects this as a "Peak" and charging is terminated. This is an especially useful feature to prevent overcharging cells. The higher the Voltage Threshold setting is, the hotter the cells get. High cell temperature is detrimental to the overall longevity of the battery pack. In general, NiCd packs can charge and peak normally using a 12mV/cell setting, while NiMH packs (3000mAh sub C's) require a much lower setting of 4mV/cell. The NiMH2 mode does not use Voltage Threshold.

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