TECHNICAL SUPPORT
Published 2026-03-09
When you were choosing the SG90 microservo, were you dazzled? Faced with a bunch of numbers and parameters, you feel like you have no idea where to start. Are you afraid that making the wrong purchase will affect the entire project? Don’t worry, today we will thoroughly reveal the “trump card” of this classicservo, so that you will know how to choose and use it after reading it.
The torque of the SG90 is usually what everyone is most concerned about when purchasing, but many people tend to ignore the unit. What does "1.2kg·cm" written on the data sheet mean? You can imagine it as being able to lift an object of 1.2 kg at a distance of 1 cm from the center of the steering gear shaft. The shorter the length of this moment arm, the greater the force it can drive.
But in actual projects, whether this torque is enough depends on your specific application. For example, when making a car steering mechanism, the moment arm is very short, 1.2kg·cm may be more than enough. But if you want to use it to directly drive a long robotic arm, it may seem powerless. It is recommended that you use a formula to estimate the load before starting. This can save you a lot of rework.
This problem is encountered by almost every novice. The standard SG90servohas a rated operating voltage of 4.8V to 6.0V, which is what we often call about 5V. You can safely connect it to the 5V pin of the Raspberry Pi and it will work very stably.
Here is a little reminder. For convenience, some people directly use 3.3V to power the servo. As a result, they find that the servo is weak or even does not turn at all. This is because the voltage is insufficient, and the motor inside the servo cannot reach the rated speed, so it naturally loses power. Therefore, if you want it to achieve its nominal performance, giving it a sufficient voltage of 5V is the basis.
The SG90s on the market all look similar, but there are actually several types, such as those with plastic teeth and those with copper teeth. If your project is to make a small fan or gimbal with a small rotation angle and light load, then the standard version of the plastic gear SG90 is completely sufficient and has the highest cost performance.
But if your project is to make robot legs or robotic arms that require frequent rotation and may be subject to some impact, then I suggest you spend a few more dollars to choose the version with metal copper teeth. ️ When plastic teeth encounter stalling or strong impact, the gears will easily slip or collapse, while copper teeth will be more wear-resistant and durable. Spending a little money to upgrade can avoid a lot of subsequent maintenance troubles.
Controlling the SG90 is not as complicated as you think. It relies on a series of pulse signals. To put it simply, the servo will "see" the signal you give it every 20 milliseconds (that is, a frequency of 50Hz). You just need to change the duration of the high level in this cycle to tell it which angle to turn to.
In terms of specific operation, if a high-level pulse is given for 0.5 milliseconds, the servo will turn to 0 degrees; if given 1.5 milliseconds, it will turn to 90 degrees; if given 2.5 milliseconds, it will turn to 180 degrees. Many programming libraries now have encapsulated these details for you, and you only need to call a simple "write angle" function. Understanding this underlying principle can help you feel more confident when debugging.
You may think that with such a small servo, how serious is the heat? In fact, the temperature of SG90 will rise rapidly when it is working continuously or is blocked. Because it is a small DC motor inside, it is inevitable that the coil will heat up when the current is too large. Overheating for a long time will accelerate the wear of the internal plastic gears and even burn out the motor.
How to avoid it? First, do not keep the servo at a difficult angle for a long time, such as forcibly breaking it. Second, before batch installation, it is best to let it run continuously for more than ten minutes under the working conditions you set, and touch the casing with your hands. If it is hot, you need to consider adding a heat sink, or check whether your control program is causing excessive stress on the servo.
After getting a new SG90, or finding that the servo is not obedient, how can you quickly determine whether it is healthy? The first step is to gently turn the output shaft of the servo manually. A good servo will have a clear sense of resistance when turning without power, and the gears will bite tightly and will not become loose.
The second step, and the most critical, is to power it up without connecting the signal line. Under normal circumstances, the servo should automatically return to its 0-degree position and remain in this position. You will feel a continuous holding force when you turn it off with your hands. If it can return to the center, and the holding force is very "steady" and there is no jittering feeling, then it is basically good. If it spins around on its own after power is turned on, or has no response, there is probably something wrong with the internal potentiometer or control board.
Having said so much, I wonder if you now have a clearer understanding of the temper of the SG90 servo? When you were working on a project, have you ever encountered pitfalls because you didn't understand the servo parameters? Welcome to share your experience in the comment area. Let’s communicate and avoid pitfalls together. Don’t forget to like and share so that more friends can see it!
Update Time：2026-03-09
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