What are the Differences of Two-stroke and Four-stroke Engine?

Posted on May 30, 2013 by mbuynow

In this post, we will share two internal combustion engines; they are the most common in the market.

A two stroke engine also called two-cycle engine means one stroke in each direction. It can complete a power cycle in only one crankshaft revolution and with two strokes. On the return stroke new fuel mixture is inserted into the cylinder. Here, “Stroke” refers to the movement of the piston in the engine.

Compared to two-stroke engines, the four-cycle engine has one compression stroke and one exhaust stoke. It uses the piston completes four separate strokes—intake, compression, power, and exhaust. The compression stroke compresses the fuel air mixture prior to the gas explosion. The exhaust stroke simply pushes the burnt gases out the exhaust.

How they work?
Two- stroke engine is simple as it has no valve, fuel and air in the cylinder have been compressed, and when the spark plug fires the mixture ignites. The resulting explosion drives the piston downward.

For four-stroke engines, piston travels down the cylinder while the intake valve is opened to allow a mixture of fuel and air to enter the combustion chamber. This process is called intake. Then the piston travels back up the cylinder thereby compressing the gasses after intake valve closed. After compressing, the spark plug ignites, and forces the piston down. The last cycle is the exhaust valve is opened, and then the piston will clear the chamber to start the process over.

Each time the piston rises and falls it turns the crankshaft that is responsible for turning the wheels. This is how fuel is converted into forward motion.

Main Differences (Are Two-Stroke Engines Better than Four-Stroke Engines?)
1. The two stroke engine only fires 1 time in each revolution whereas four stroke fires 1 time in 2 revolutions.
2. Two stroke comes with a light-weight body and simple design (has no valve, the piston act like a valve to control the flow of fuel), thus, it is less expensive to manufacture. But the four stoke is more versatile.
3. Four-stroke engine has a much higher efficiency than the two-stroke
4. Four-stroke engine is lower fuel consumption
5. Application
Two stroke engines are used for lower-power applications (dirt bikes, mopeds, jet skis, small outboard motors, as well as radio-controlled model planes) while four strokes are using in heavy duty, like automotive industrial, cars, trucks, and generators.
6. Two-stroke engines often provide high power-to-weight ratio and have a greatly reduced number of moving parts.
7. Two-stroke engines can work in any orientation, which can be important in something like a chainsaw.

GF26i V2 Engine 26cc 2 Stroke Gasoline Engine

How to Build a Brushless DC Motor?

Posted on May 28, 2013 by mbuynow

Anyone can build your own brushless DC motors. Brushless DC electric motors are also named BLDC motors that are synchronous motors that are powered by a DC electric source via an integrated inverter/switching power supply. The controller of BLDC motor is easier to build and it has better torque characteristics than some other types.

Today, we will discuss how to build a simple brushless DC motor.

Structure

To build a motor right, you need to understand some basics of brushless DC motors. BLDC motor uses a rotating permanent magnet in the rotor, and stationary electrical current/coil magnets on the motor housing for the rotor, but the symmetrical opposite is also possible. A motor controller converts DC to AC.

How does a BLDC motor works?

Unlike brush DC Motor counterparts, the Brushless DC Motor does not contain any carbon brushes. Instead, the electromagnets within the motor remain stationary along with the armature, while the encased permanent magnets rotate, generating torque. The Brushless DC Motor is synchronous; both the stator and the magnetic field generate the same frequency, therefore avoiding any type of “slip” most induction motors exhibit.

Requirements

Laminations

Eddy current cause heat loose which essential take away from the possible output power of the motor. Typically professionally mode motors have laminations that are no more than half of a millimeter thick.

Magnets

Motors can be made using any type of magnet, either that be the less powerful ferrite magnets or the more powerful neodymium magnets. To meet this demand neodymium arc magnets where used with an N50 rating.

Windings

Get number of windings you want.

Wire

It was preferable to do a thicker gauge wire so more current could flow at the cost of less turns. A wire gauge size 23 with a fussing current rating of 35A, which is more than will ever be put through the motor, was used.

Summary

The motor took a very long time to design, and the biggest factors that limited the motor were cost and how the motor would be machined. Just building a brushless DC motor out of house hold things isn’t very practical. Usually, we would suggest you buying one already assembled.

Differences of AC Motor and DC Motor

Posted on May 26, 2013 by mbuynow

Today, we’d like to share you with the differences of AC motor and DC motor as they are the most common in our life.

The same
Both motors work by basically positive and negative current chasing itself in a circle which never catches up to itself so the motors turn, and then converting electrical energy into mechanical energy.

Differences
If you’re familiar with AC and DC motor, you may find that their power, construct and control are different.

brushed DC electric motor

AC or alternating current motors are powered from alternating current while DC or direct current motors are powered from direct current, such as batteries, D.C. power supplies or an AC-to-DC power converter. The DC motor includes a brushes and a commutator while AC induction motors do not use brushes. For the difference of speed control, DC motor is controlled by varying the armature winding’s current while the speed of an A.C. motor is controlled by varying the frequency.

Advantages and disadvantages
Efficient
AC brushless motor is more efficient than DC motor. In AC, polyphase or three phase motors this becomes more efficient because you need lower current to do the same thing a DC motor does which requires more voltage to push it. Thus, AC motors are better suited for high speed operation (over 2500 rpm) since there are no brushes, and commutation is not a problem.

Speed control
DC motors with a better speed control than AC. Thus, DC motors are often use in rock crushers, car crushers, etc. A lot of your home appliances ironically run on DC motors too. In additional, there are various methods to control the speed of a DC motor, such as field flux control, armature control method, and voltage control method.

Maintenance and life
AC motors require virtually no maintenance and are preferred for applications where the motor is mounted in an area not easily reached for servicing or replacement. So they are very rugged and have long life expectancies. On the contrary, DC motors need more maintenance, limit the speed and usually reduce the life expectancy.

Price
DC motors are easy to build as they are less complex with a single power conversion from AC to DC and very cost effective for most horsepower ratings.

How to Control the Speed of a DC Motor?

Posted on May 24, 2013 by mbuynow

Nowadays, AC motors have a far greater percentage of electric motors in service. However, the DC motor is of considerable industrial importance. The advantage of a DC motor is that its speed can be changed over a wide range by a variety of simple methods. Then, we may have a question: why we need to control the speed of a DC motor?

High power systems for RC model can be very dangerous; sometimes it may become a killer. The motor should only rotate in a rated speed; if the speed is more than rated speed then the motor will be damaged.

How to control the speed of a DC motor?

See more our post How to Choose the Right Speed Controller?

There are several of methods to control the motor speed, such as armature control method, field flux control and voltage control method. To control the speed of motor a rheostat should be connected to the field side of motor, by varying the rheostat we can control the speed of motor.

First, we may learn about how the DC motor works?

The speed of a DC motor is given by:

It is clear that there are three main methods of controlling the speed of a DC motor, namely:
(i) By varying the flux per pole (f). This is known as flux control method.
(ii) By varying the resistance in the armature circuit. This is known as armature control method.
(iii) By varying the applied voltage V. This is known as voltage control method.

Flux control method
In this method, the flux is reduced (and hence speed is increased) by decreasing the number of turns of the series field winding. With full turns of the field winding, the motor runs at normal speed and as the field turns are cut out; speeds higher than normal speed are achieved. This method is usually employed in the case of fan motors.

Armature-resistance control
There is a variable resistance directly connected in series with the supply to the complete motor which reduces the voltage available across the armature and hence the speed falls. By changing the value of variable resistance, any speed below the normal speed can be obtained.

Voltage control method
In this method, the voltage source supplying the field current is different from that which supplies the armature. Thus, this method avoids the disadvantages of poor speed regulation and low efficiency as in armature control method. However, it is quite expensive. Therefore, voltage control method is employed for large size motors where efficiency is of great importance.

How to Choose the Right Speed Controller?

Posted on May 22, 2013 by mbuynow

Electronic speed controller is also called ESC; it is a necessary upgrade part for your RC model. High power systems for RC model can be very dangerous, ECS allows for easy speed control adjustment, essentially providing an electronically-generated three phase electric power low voltage source of energy for the motor.

Nowadays, brushless motors have become very popular with radio controlled hobbyists because of their efficiency, power, longevity and light weight in comparison to traditional brushed motors. In additional, speed controls determine whether your vehicle can go in reverse. If you are not racing on a track, you’ll probably want to get a reverse speed control.

Here is a quick guide on how to choose your motor electronic speed controller for your brushless motor.

Brushless motor types and ESC
There are two types of brushless motor. The sensored motor includes sensors to transfer exact information to the speed control, making the sensor speed control more precise. These motors are highly prized by experienced racers who are always looking for an edge in the competition.

On the contrary, sensorless speed controls and motors can only estimate the position of the rotor. And speed control has to make its best guess to what is the correct pulse to send to make the motor go forward or reverse when the transmitter trigger is pulled or pushed. However, by coming to a complete stop, letting off the trigger, and then applying forward throttle again you will generally then go forward.

Motor ESC

Limits and price
ESCs are available with many different features, limits, and price ranges. An ESC will have a power limit. To handle more power, the ESC needs to be larger, heavier, and is more expensive. It’s important to know the peak current your motor is going to pull at full throttle. An ESC’s limit is the lowest number of turns that it can handle. The lower turn motors it can handle, the more expensive.

This determines the current rating you should look for in an ESC. Always choose an ESC with a current rating that is higher than what you need. If the motor is going to pull 12A, a 25A-rated ESC is a much better choice than a 10A-rated one. The 10A ESC will probably overheat and cook, even if you only fly at half throttle.

All ESCs have voltage limits. Some even have more than one! Choose an ESC that is designed to work with an equal or higher voltage.

The Most Important Factors You Should Consider When Choosing Brushless Motor

Posted on May 20, 2013 by mbuynow

How to choose a proper motor for your RC plane, helicopter or RC car? An instruction can tell you a particular motor to get but what if you had none or were designing a plane how would you choose? There are always a ton of threads about motors and ESCs and they are all usually variants on the same questions. Even though, we still want to share some choosing tips for new beginners.

A brushed system needs a lot of maintenance, but offers more flexibility because you can change motors depending on track conditions (how much torque you need). A brushless system on the other hand, needs almost no maintenance.

Brushless speed ratings
If you want to choose brushless electric motors for your car, the first thing to consider is how fast you realistically want the car to go. But there are two important factors you need to consider are your abilities and budget. For example, you may want your cars going 50mph, but there are only a few of us who have enough driving experience to go that fast without hitting straight into a wall.

This is similar to airplane; too much RPM will require a small prop which may not allow for enough thrust for the boat to get on plane. If a high RPM setup runs too large of a prop, excessive heat will be the result.

There is no standard for measuring the speed of the brushless motor. Some manufacturers measure the speed by turns, others use a KV rating. These terms are important to you because they will help you choose your motor’s speed.

In short, the fewer the turns on a brushless motor, the faster will be the acceleration (or spin of the armature). For a KV measurement, the higher the KV number, the faster it will accelerate.

The basics on turns and winds are as follows:
Lower Turn = Higher Top End/Less Torque
Higher Turn = Lower Top End/More Torque

If you just want to learn and play for fun, then you may choose the lower KV rating motor. On the contrary, you are getting a brushless motor for a racing, and then the fewest turns or the highest KV rating is the best choice.

Sensored or Sensorless
Brushless motors must be run from a speed controller, and there are two types brushless motor: sensored and sensorless system. The first one gives the feeling of the vehicle responding accurately to even the smallest changes of speed. These motors are highly prized by experienced racers who are always looking for an edge in the competition. A sensorless brushless motor doesn’t know how to tell whether it’s at the 12 or 6 o’clock position, so the speed control has to make its best guess to what is the correct pulse to send to make the motor go forward or reverse when the transmitter trigger is pulled or pushed.

Brushless combo Leopard 60A ESC combo

If you want to get an affordable brushless motor, you may consider the LEOPARD 60A ESC combo, it is sale under 58.90 pounds and include a brushless motor, an electronic speed controller and program card. Thus, you don’t need to consider whether the ESC is sensored or sensorless, as well as the budget.

What Factors Need to Consider when Choosing a Green Laser Pointer?

Posted on May 18, 2013 by mbuynow

As we all known, the first lasers ever designed to be used as a suitable hand held laser pointer device were red laser. But nowadays, green laser pointers become the most popular as they are superior to the red ones.

There are so many cheap laser pointers and brand manufactures in the market, choosing the best green laser pointer become a hard task. After all, a laser is never safe if you use it in wrong ways and if you use the ‘wrong’ ones. Thus, you may choose the best one based on what you need, knowing how to test for defects, as well as get a warranty or guarantee on the product.

So what factors you need to consider of green laser pointer? Are style, power, functions, battery, warranty, and price?

Power
First, you need to consider about the laser power. For example: star gazing with a pointer takes a lot more power than pointing at a presentation board in the same room. Thus, if you just need to get them for your presentation, a maximum output less than 5mW is power enough. Also the classified as class 2 or 3R is safe for use according to the label. Do not use Class 3b or 4 products.

Quality and defects
For low power (below 20mw) lasers, if the light turns from dark color to brightened color, then there may be something wrong with the circuit or LD of this laser pointer. The quality for a laser pointer is very important. When testing a laser pointer, keep track of its color and watch for changes, because fluctuations can indicate a problem with the light-emitting diode.

Appearance and material
What appearance the green laser pointer do you want to get? Small and light-weight green laser pointer pens are common on the market, most of them are comes with a clip to secure to a shirt pocket. Other shorter and thicker laser pointers feature a keychain. A green laser pointer that resembles a fancy pen might even come with a case to further fool other people.

Material related to the price of laser pointer. The plastic is the cheapest, metal and aluminum are a little bit expensive. If you want to use for a long time, then keep away the plastic ones.

Warranty
Some low power laser pointers are cheap, others can be expensive. So warranty should be a part of factors for choosing laser pointers. Make sure to get a warranty or at least a money-back guarantee to easily solve this problem.

Most retailers provide warranty guaranteed, such as mBuyNow, they provide six months limited product warranted even for a ten pounds laser pointer.

RC Hobby Mysteries: What is Brushless Motor?

Posted on May 16, 2013 by mbuynow

Have you ever wondered what the mysteries of brushless motors are? How does it work? Why it becomes more and more popular though it was much more expensive than brushed motor? Well come with us on a voyage of discovery.

First, we need to learn about what’s brushed motor and brushless motor.

What’s brushed motor?
Brushed motor is also known as a brushed DC electric motor. It is an internally commutated electric motor designed to be run from a direct current power source. Brushed DC motors have been in commercial use since 1886. So it has a very long history. They can be varied in speed by changing the operating voltage or the strength of the magnetic field.

In a brushed motor, an electromagnet is mounted on a spinning arm, called an armature or rotor. The armature sits between two magnets set in a horseshoe configuration, collectively called the stator. When power is fed to the electromagnet, the arm moves, aligning the north and south poles of the electromagnet with the opposing poles of the stator.

What’s brushless motor?
So you may have a basic knowledge of brushed motor. Then we have a glance of brushless motor. Just as the name implies, there is no brush.

brushless DC motor

Design
The brushless motor turns this design inside out. Magnets are placed on the armature and are surrounded by one or more electromagnets. The current switch is controlled by computer, turning electromagnets off and on by switching the current; the computer can also factor in the motor’s current speed to optimize efficiency, all without the need for brushes.

How it works?
A DC Brushless Motor uses a permanent magnet external rotor, three phases of driving coils, one or more Hall Effect devices to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors, they act as three-phase synchronous motors containing their own variable frequency drive electronics.

Application
Brushless DC motors have been used in many applications, particularly devices such as computer hard drives, CD/DVD players and radio control models. Brushless motors are a popular motor choice for model aircraft including helicopters. Also, the brushless motor is also popular among remote control (RC) racing enthusiasts. As it boasts better performance and suffers less wear than brushed motors of similar size; they can provide a great amount of power to RC racers.

If you have any confuse of brushless motor, feel free to contact us.

mBuyNow Launch 120A ESC Speed Controller with Bluetooth Module

Posted on May 14, 2013 by mbuynow

Toro TS 120A ESC speed controller is designed for 1/10 scale RC cars, It can be programmed by program box, PC or smart phone via Bluetooth module. And firmware can be updated by connecting the ESC with PC or smart phone, says mBuyNow.

mBuyNow has launched the brand new Toro 120A ESC speed controller. Users can set the turbo and boosting timing to improve the motor RPM to get its best performance.

Toro 120A ESC features low voltage protection, motor and ESC overheat protection and signal lost protection. The internal resistance can be reduced by laminated copper stack control technology and cooling fan design (8V 0.2A 20000RPM) so that the dynamic thermal equilibrium can be got. In this case, the aluminum heat sinks can works effectively.

Well-performed throttle and brake control function could control the punch/brake rate by point and the point can be set by user. The precision of the punch/brake rate is 1%. And the user could also custom the throttle/brake curve.

This unit is also capable of programmed by PC or mobile phone via Bluetooth module. Users could modify the setting, monitor the ESC and motor status at any time by smart phone.

There is nothing out there quite like this speed controller. The users could set and store 10 sets of profiles in the ESC. These data could be called out at any time without any special program setting. All the setting can be exported or imported so that the user could compare and analyze.

Technology and RC enthusiast don’t need to spend hundreds of pounds for an ESC or even close to a hundred pounds. The Toro Ts 120A brushless motor speed controller provides them with bleeding edge technology for the fraction of the cost.

mBuyNow Launches New Toys and Games

Posted on May 12, 2013 by mbuynow

mBuyNow has released newest toys and games. Currently, only the kid toys are available. All of them are organic and made of high quality eco-friendly material at affordable price of lowest as 1.95 pounds. Let’s take a look at these fantastic toys.

Wooden toy car is recommended for ages 2 to 6 years old. It comes with 20.5*8.5*7.5cm, very perfect shape for grip. The wheels and body is well built to ensure long time playing.

Rust red metal car and scarlet metal car are designed for ages 3-10 years old children. Features small size, it is easy to hold on. The two car toys are a good education for your kid to learn about vehicle as well as entertainment.


Fashion Metal Car	Body Massager	Sling Shot

Sling shot is intended for using by those 18 years of age or older. It is small, light-weight and can be fold up, so you can fit it in your pocket and take it anytime and anywhere you want. Features a non-slip handle grip which can help your shot more accurate, this cool gadget can shot exceed 100

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Wooden back and body massager is a useful gadget as well as an interesting toy. You can use it to relax your body like other massagers, with 18*8.5cm small size and only weight 245g, this cool gadget also can be used as a kid toy.

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Please visit www.mBuyNow.com to check out our great toys and game and other radio control hobbies.

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Monthly Archives: May 2013