TECHNICAL SUPPORT
Published 2026-05-09
Opening narrative
Tiny servo servo guo hua microservoA00090 is an item that has sparked heated discussions in the circle of model enthusiasts in recent years. Its length is less than three centimeters and its weight is as light as a sparrow egg, but its torque output can reach five kilograms·cm. This evaluation does not involve unreal content, but only tells you its advantages and disadvantages based on actual machine operation and common examples.
Looking at its appearance, the color of the outer shell is dark, and the connecting gaps are very tight. There is a cross-shaped rocker arm on the top with very fine tooth grooves; there are screw holes on the four corners of the bottom cover, arranged like an array. Use your fingers to gently move it, and the spring that returns to the middle position is very stiff, and the amount of deviation is extremely small.
Some players once installed the machine but failed to calibrate the neutral point, causing the steering arm to deflect three degrees. Then the plane rolled over just after takeoff, and eventually fell to the ground, causing the blades to break. We can know from this incident: The midpoint must be set correctly during the first installation, otherwise small deviations will lead to serious disasters.
Starting from the top to the bottom, there is such a spatial sequence, the connection is: the rocker arm, then becomes the housing, then passes through the gear set, then to the motor, then the circuit board, and finally the bottom cover. The parts on each layer fit very closely, without any false space. The gears used internally are a mix of metal and plastic - the first stage is made of plastic to cushion the impact, and the last stage is made of metal to transmit high torque. This kind of design is relatively common among hundreds of yuan-level servos, and its purpose is to balance the relationship between cost and durability.
It has such nominal parameters: its operating voltage is within the range of 4.8V to 6.0V, the locked-rotor torque is 4.5kg·cm at 6V, and the rotational speed is 0.12 seconds per 60°. During the actual test, when the power supply was 6V and a 500g weight was mounted on the 1cm arm, lifting the arm was simple and there was no jitter. However, when the weight was changed to 800g, a slight delay began to occur.
If someone asks: "Why not just install a 2kg load directly?" Then explain it through counter-evidence: Someone installed A00090 on the steering mechanism of a 1/10 climbing car. When the wheel got stuck on the stone, the device's locked-rotor current surged to 1.8A, and then the steering gear became very hot. However, this device is still working after being blocked for three minutes, but the outer shell is slightly warmer. It can be seen that its overload capacity is more advantageous than most products in the same price range.
Keywords: Torque linearity
As the load gradually increases, the torque shows a linear attenuation trend. When it reaches the node of 4.2kg·cm, the speed begins to decrease. Such a feature is particularly valuable in terms of robotic arm joint control. It can predict the force output in advance and avoid jumping.
Taking the quadcopter gimbal as an example, a pilot used A00090 to replace the original plastic gear servo without changing the PID parameters. As a result, the gimbal experienced low-frequency tremors and the screen appeared jelly-like.Later, after careful investigation, the reason was that the response speed of the metal gear servo was faster, and the original PID had overshoot.. After lowering the P value to 0.8 times, the tremor disappeared.
This case shows that when a steering gear with different damping characteristics is replaced, the control system needs to be adapted again. This is not an error caused by the servo itself, but caused by a lack of matching.
In terms of wiring, the sense of space needs to be further extended: the socket is a three-wire JR type, the length of the wire is 25 cm, and it is a silicone soft wire. Threading it through 25mm carbon tube has no problem. When the rack is relatively small, the outer skin can be peeled off, leaving only the signal cable and power cable, thus reducing the weight by 1.2 grams.
The actual measured speed is that at 5V voltage, the time it takes to change from 0° to 60° is 0.14 seconds. However, at 6V voltage, the speed increases to 0.11 seconds, which is consistent with the nominal 0.12 seconds.
For bionic robot foot joints, if you want to use divergent thinking, you need to meet speed and accuracy requirements at the same time. An educational robot team used A00090 to build a six-legged spider with a gait cycle of 0.5 seconds per step. After the servo has been running continuously for two hours, the midpoint deviation is only 0.8°, and the centering error is less than 0.3°.
In contrast, another team used a cheap steering gear (the model is omitted here). After the same two hours, the yaw reached 4°, and the robot kept spinning in place.. It can be seen from this that the potentiometer and silicon control chip of A00090 are indeed sincere.
Keywords: response lag
The electrical hysteresis, calculated from the time the command is issued to the time of startup, is about 3.2ms. The mechanical hysteresis, that is, the gear gap, is about 0.5°. This kind of data is better than most products in the same price range. Competitive products are generally 5ms plus 1.2°.
Ten years ago, the market for micro servos was monopolized by foreign brands, and their prices were as low as two hundred yuan each. Today there is guo hua microservoA00090, it achieves similar performance with a price of less than 40 yuan.
As can be seen from the table, technological advancement has generally benefited players. However, special attention should be paid to the fact that the waterproof level of A00090 is IP40, so do not let it come into contact with water; the ball bearing only exists at the output end, and the input end uses a copper sleeve - this is a sacrifice based on cost.
Q1: Is this servo suitable for steering 1/8 off-road vehicles?
One situation is that it is not applicable because there is insufficient torque. For a 1/8 car, the required torque must be at least 10kg·cm. In addition, this is the case with A00090, which is suitable for scenarios such as 1/18 or 1/16 cars, and is suitable for scenarios where the servo load is less than 5kg·cm.
Q2: Jitter occurs after long-term use, how to solve it?
First check whether the power supply is stable. Most of the jitter is due to insufficient BEC output, so just use an independent UBEC or capacitor to stabilize the voltage.
Q3: Can it be directly replaced by SG90?
A: The sizes are compatible, but the torque of A00090 is relatively large. You need to confirm the specifications of the rocker arm screws, which is the difference between M2.5 and M2.. It is recommended to purchase the matching rocker arm bag.
Q4: What is the PWM period and pulse width range during programming control?
The period is 20 milliseconds, the pulse width is from 0.5 milliseconds to 2.5 milliseconds, which corresponds to 0 degrees to 180 degrees, the center is 1.5 milliseconds, which is 90 degrees, and the dead zone is 3 microseconds.
Q5: Can the gear set be purchased separately?
For the time being, there are no retail sales of original gears on the market. If teeth scanning occurs, you can buy a metal gear set of the same specifications. The price of this set is about 8 yuan, and then replace it by yourself. You must pay attention to the diameter of the final gear shaft to match each other.
Keywords: temperature rise drift
After thirty minutes of continuous operation, the temperature of the case increased by approximately fifteen degrees Celsius (ambient temperature was twenty-five degrees Celsius). At this time, the midpoint of the steering gear drifted by 0.2 degrees, which was within the allowable range. If the temperature rises above 25 degrees Celsius, then the load or ventilation needs to be checked.
Taking a comprehensive look at the overall situation, guo hua microservoA00090 is at the price level of more than 30 yuan, providing almost industrial-level linearity and low-level hysteresis performance. The scenarios it is applicable to are clear and clear, and they exist in the joints of small robots, the driving links of micro aircraft surfaces, the field of educational robotic arms, and the field of 1/18 model steering.
Three core views reiterated
1. Excellent torque linearity, suitable for feedback control scenarios.
2. One kind of durable thing is a metal gear, but there is a situation that you should pay attention to, that is, the first-stage buffer plastic teeth have a fatigue life problem, which needs to be taken seriously. After about 5,000 impacts, it is recommended to have an inspection.
3. The response speed is the same as that of imported brands, and the price/performance ratio is outstanding.
Suggestions for action
First use: Use a servo tester to calibrate the midpoint, do not install blindly.
Power supply requirements: 2A or above BEC, avoid sharing ESC with motor.
Perform regular maintenance. Every two hours of operation, check whether the rocker arm screws are loose. Every six months, a very small amount of lithium-based grease needs to be added to the output bearing.。
Back to the original question: Is it worth buying?——If your project’s torque requirements are within the range of 5kg·cm, and you are pursuing metal teeth and low hysteresis, then A00090 is undoubtedly the most rational choice at this time.. On the contrary, if it requires high torque or waterproofing, then you have to find other ways. Choose the appropriate type rationally to achieve long-lasting results.
Update Time：2026-05-09
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