TECHNICAL SUPPORT
Published 2026-03-29
Have you ever had the idea of installing aservoon a robot or creative product so that it can continuously spin in circles like a windmill? Many friends will have this idea when they first come into contact with steering gear. In fact, ordinaryservos cannot rotate all the time, but there are models on the market that can rotate infinitely.
Today we will discuss this interesting topic to help you thoroughly understand the secret of the steering gear's "circle rotation".
There is a potentiometer inside the ordinary steering gear to detect the angular position of the output shaft. When it reaches a preset limit position (such as 180 degrees or 270 degrees), the mechanical structure will be stuck and cannot continue to rotate. It's like our wrist, we can turn it left and right, but we can't turn it all the way in one direction.
So if you have a standard servo on hand, don't force it. Forcing an ordinary servo to "turn" in a circle will damage the internal gear at worst, or burn out the control circuit at worst. To put it simply, the original intention of the ordinary servo design is to stop at a certain angle accurately, rather than rotating all the time.
Strictly speaking, a true 360-degree continuous rotating servo does exist, but its working principle is completely different from that of an ordinary servo. The continuously rotating servo eliminates the angle limiter and uses a potentiometer or Hall sensor internally to detect speed rather than absolute position. You can think of it as a miniaturized reduction motor plus drive board.
So can it turn 360 degrees? Not only can it turn 360 degrees, but it can also turn countless 360 degrees. However, it should be noted that this kind of servo cannot control the specific angle at which it stops. It can only control the direction and speed of rotation. If you need to control a few turns and then stop at a precise location, a continuous servo is not suitable.
The continuous rotating servo is extremely convenient in actual use. Its signal line is the same as that of an ordinary servo. It is also composed of three lines, namely power, ground and signal lines. When you send it a pulse signal of 1.5 milliseconds, it will stop rotating; if the pulse width is less than 1.5 milliseconds, it will rotate counterclockwise, and the narrower the pulse width, the faster the rotation speed; if the pulse width is greater than 1.5 milliseconds, it will rotate clockwise.
The operating principle of the continuous rotation servo is clear. Its signal wires are the same as those of ordinary servos, which are the power supply, ground wire and signal wire. When a pulse signal of 1.5 milliseconds is given to it, it will stop rotating; if the pulse width is less than 1.5 milliseconds, it will start to rotate counterclockwise, and the narrower the speed, the faster it will rotate; and when the pulse width is greater than 1.5 milliseconds, it will rotate clockwise.
For example, if you want the servo to rotate slowly in a circle, you only need to give a fixed pulse signal of 1.3 milliseconds, and it will continue to rotate counterclockwise. Used on robot wheels, conveyor belts or automatic rotating booths, the effect is great. Many makers will give priority to this kind of continuous servo when making smart cars or automatic feeders.
Many friends are worried that the servo will overheat and burn out if it rotates continuously for a long time. This depends on the mass and load of the servo. Good quality continuous servo has overheating protection and current limit inside, so it can work for a long time. But if you put a heavy load on it, or the rotor is blocked, the current will rise sharply and the temperature will soon exceed the standard.
For safety reasons, it is recommended not to exceed the rated load and to give the servo a rest every one or two hours. If you need to run 24 hours a day, it is best to choose an industrial-grade continuous rotating servo, or add a heat sink to the servo. Remember, when selecting a model, look clearly at the "continuous working time" and "maximum current" in the product parameters.
If you have a few ordinary servos that are idle, don’t throw them away in a hurry. In fact, you can transform them into continuous rotating servos by yourself.
The first step is to carefully disassemble the casing of the servo, carefully look for the mechanical limit bump on the output shaft, and then use a small file to gently smooth it. The second step is to accurately adjust the rotating shaft of the internal potentiometer to the middle position, and then secure it firmly with glue so that it no longer rotates with the output shaft.
The most critical step is the processing of the feedback circuit. Since the potentiometer has been fixed, you have two options at this point. One is to add an additional op amp circuit to simulate the angle signal, and the other is to directly purchase a ready-made "continuous servo modification kit". For friends with strong hands-on skills, this modification project is quite interesting and can also help you save a lot of money. However, if you are a novice, it is still recommended to purchase the finished continuous servo directly, so that the stability is more guaranteed.
When you make up your mind to buy a servo that can continuously rotate in a circle, be sure to remember to pay attention to three core parameters: torque (kg·cm), rotational speed (seconds/60 degrees) and operating voltage. The role of torque is to determine how many objects the servo can drive, and the rotational speed will affect the speed of the servo's rotation. The requirement for the working voltage parameter is that it must match your control board. For example, if it is powered by 5V, it must not be directly connected to a 12V servo.
When choosing a servo that can keep turning in circles, these three core parameters cannot be ignored. The torque is related to the weight of the object that the servo can carry, the rotational speed determines the speed of its rotation, and the working voltage needs to be adapted to the control board. In the case of 5V power supply, it cannot be directly connected to the 12V servo, otherwise the device may not work properly or even be damaged.
Also carefully consider the type of steering gear. If you just need the servo to "turn up", then choose the continuous rotation servo; if you need the servo to "turn to a specific angle and then stop", then use the standard servo in a formal manner. Don't have any expectations that a servo can achieve precise parking and infinite rotation. There is currently no product on the market that can take into account the advantages of both. Only by making choices based on your actual needs can you create a useful product.
After reading this article, do you have an idea of whether the servo can keep turning in circles? Have you ever experienced project failure due to choosing the wrong servo? Welcome to share your story in the comment area, let’s avoid pitfalls together~ If you find it useful, don’t forget to like it and forward it to more friends who make products!
Update Time：2026-03-29
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