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Published 2026-03-02
When I first came into contact withservos, I was also confused by the word "9g". I’ve seen product titles that say “servo9g”, but what does it mean, and what does it have to do with making models and making small inventions? Today we will talk about it thoroughly so that you can choose a steering gear with confidence.
When many people first come into contact with related concepts, their first reaction is often to think that "9g" represents the thrust or torque of the steering gear. However, this is not the actual situation. The "g" here is actually a simple unit of weight "gram". The so-called 9g means that the weight of the servo is about 9 grams. This is a conventional classification standard in the industry, and its function is mainly used to distinguish micro and small servos.
You can think of it like buying a mobile phone. When we usually say "this phone is 180 grams", it also refers to the weight. The message conveyed to you by the servo 9g is that this is an extremely lightweight micro servo, which is particularly suitable for scenes that have strict weight requirements, such as small drones or mini robotic arms.
This is the core question. The torque of 9g servo is usually expressed in "kg·cm", and common models are between 1.5kg·cm and 3kg·cm. This value means that it can pull up to 3 kilograms of objects at a distance of 1 centimeter.
For example, use it to drive various joints of a small robot, accurately control the tail rudder of a fixed-wing aircraft, or make a delicate small box that can automatically flip its lid. Its capabilities are fully capable of meeting these needs. However, if you try to use it to push a heavier robotic arm, it is likely to malfunction, as if it has entered a "strike" state. In fact, the key to determining whether it is adequate for a certain task is how much load weight you need to carry.
In addition to torque, there are two parameters you must look at. The first is speed, usually expressed in "seconds/60 degrees", such as 0.1 seconds/60 degrees. This parameter determines how fast the servo rotates, which is more important for remote control cars that pursue sensitive movements.
The second important point is the angle range. Among the common types of servos, 9g servos can generally only rotate 180 degrees, but there are also some special models that can achieve 360 degrees of rotation and even continuous rotation.
When you plan to make a small fan, you obviously need a servo model that can rotate continuously; and if you plan to make a mechanical finger, a 180-degree rotation range is sufficient. Only by clearly understanding these two key parameters can we purchase a steering gear that truly meets the actual use requirements.
The connection is actually very simple. The 9g servo leads to three wires: the brown one is usually the negative pole (GND), the red one is connected to the positive pole of the power supply (VCC), and the orange or yellow one is the signal wire. You just need to connect it to a microcontroller or receiver and it will work.
There is a little trick before using the servo. Be sure to remember to power on the servo first. After the servo automatically returns to the middle position, install the rocker arm you want to drive. This will ensure that its range of motion is accurate. In addition, you need to pay special attention to the power supply voltage. The applicable voltage range of most 9g servos is 4.8V to 6V. Do not directly connect to 12V, otherwise the servos will be burned.
Because the 9g servo is cheap and lightweight, it is an artifact for beginners to DIY. You can use it to make an automatic feeder to pour cat food for cats regularly every day; or use it with an ultrasonic sensor to make a smart trash can that opens the lid.
There are also many people who use it to make mechanical palms. Each of the five fingers uses a servo, and it can be connected to a microcontroller to achieve grabbing actions. The cost of these projects is not high, but they are very fulfilling when done. They are also especially suitable for working with children to experience the fun of creation.
Purchasing channels are critical. The servos that cost a few yuan a piece on a certain website are cheap, but the gears may be made of plastic, which makes the gears easy to sweep and the accuracy is also poor. It is recommended to go to a regular model store or electronic component mall to purchase.
When choosing, look for models with metal gears such as the MG90S. Compared with other models, their durability will be much better. During the selection process, remember to check user reviews and pay special attention to whether problems such as "jitter" and "inaccurate return" are mentioned. If you are making a formal product, it is the safest way to contact the manufacturer directly to get samples for testing. After all, in actual production, data is more reliable than any verbal description.
If you find that the servo is not moving, don’t throw it away in a hurry. First, gently turn the output shaft by hand to feel whether it is stuck or obviously loose. If the gear is swept, it will not rotate smoothly.
Then use a multimeter to carefully measure the power cord to see if the voltage is normal. Sometimes the problem is just a loose plug, which can be solved by plugging it back in again. If the signal cable is not connected correctly, the servo will also become unresponsive. Carrying out these basic troubleshooting tasks can help you save a lot of unnecessary money, and at the same time, it can also give you a clearer understanding of how it works.
In addition, during the investigation process, some details need to be paid attention to. For example, the range of a multimeter must be selected appropriately to avoid inaccurate measurement results due to improper range. For the connection of signal cables, carefully check the instructions to ensure that each cable is connected correctly. Only in this way can the troubleshooting work be completed more effectively, which not only saves money, but also provides an in-depth understanding of its working principle and provides stronger support for subsequent maintenance or use.
When you are working on a project, what interesting function do you most want to use the servo to achieve? You may wish to chat about your creativity in the comment area, and let us communicate and create more sparks together. If you find the article useful, remember to like and share it so that more friends can understand the servo and have fun with DIY!
Update Time：2026-03-02
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