TECHNICAL SUPPORT
Published 2026-03-25
When retrofitting a smart trash can, the most troublesome part is the installation of theservo. Many friends are stuck in this place when DIYing. Either theservomodel is wrong, or the cover cannot be opened or closed tightly after being installed. Looking at a pile of wires and screws, I really don’t know where to start. Today we will talk about the installation process and explain the steps clearly in plain English so that you can avoid detours.
Choosing aservois the first step and the most error-prone place. Common models on the market include MG995 and these, which are powerful and resistant, and are suitable for lifting trash can lids. If the cover is heavy or has damping, be sure not to choose a plastic servo with small torque, as it will burn after only two uses. It is recommended to buy a servo with metal gears directly. Although it is a little more expensive, it saves worry.
A simple way to judge: poke the lid of the trash can with chopsticks and feel how much effort it takes to open it. If it feels more strenuous, the servo torque must be at least 15kg/cm. Before taking action, verify it with an actual object, which is much more reliable than looking at a parameter sheet.
Where the servo is placed directly affects the effect of opening the cover. The most common method is to fix the steering gear on a flat surface behind the barrel, with the steering wheel facing upwards, and use a bracket to connect the cover. You can stop driving the screws in a hurry and fix them temporarily with double-sided tape to simulate the opening and closing action. Try it a few times to find the position where you can fully open the cover without getting the servo arm stuck.
Another method is to hide the servo inside the bucket cover, which looks cleaner, but the installation will be more difficult and you need to process the connecting parts yourself. If you are just starting to worry about it, it is safer to install it on the rear side and it is easier to maintain. When positioning, pay attention that the rotation center of the servo arm must be in line with the rotation axis of the cover, otherwise the cover will be crooked.
Once you’ve chosen the location, it’s time to fix it. Don't use self-tapping screws to screw directly onto the plastic bucket, otherwise it will loosen after a few days. First drill holes in the barrel, and then use an M3 long screw and a lock nut to secure the servo. If the trash can is made of iron, remember to use countersunk head screws to ensure a smooth surface. Before tightening the screws, check to see if the servo is crooked. If it is crooked, opening the cover will get stuck.
It is recommended to use an aluminum alloy U-shaped bracket to connect the servo arm and the cover. Many people try to save trouble by gluing them with hot melt glue or tying them with zip ties, but they fall off within three days. The stress points must be fixed with screws, which is the key to ensuring long-term use. Leave a little gap at the connection so that the cover can move freely without causing additional resistance from being installed too tightly.
The servo generally has three wires: the red wire is the positive wire, the brown or black wire is the negative wire, and the orange or yellow wire is the signal wire. The most common mistake to make when connecting is to reverse the positive and negative poles. As soon as the servo is powered on, it may burn out. You can use a multimeter to test the output of the control board and confirm it before wiring. If you are using a microcontroller or a dedicated trash can modification module, the signal line must be connected to the corresponding PWM port.
️Don’tconnect the power supply directly to the control board. The high-torque servo has a large instantaneous current and can easily burn the board. A better approach is to supply power to the servo separately, and the negative electrode and the control board can be grounded together. If you don't have a special power module on hand, use two 18650 batteries connected in series, with a voltage of about 7.4V, and most servos can be driven.
After the hardware is installed, the control logic must also be straightened out. Generally, smart trash cans need to be equipped with sensors, such as ultrasonic or infrared. When the sensor detects that a person is approaching, it triggers the servo to rotate at an angle to open the lid, and then closes it after a few seconds. You can first use a simple test program to turn the servo to 90 degrees and then back to 0 degrees to see if the cover moves smoothly.
If you find that the cover is not tightly closed during debugging, don't rush to replace the servo. First check if there is any deviation in the physical position and fine-tune the installation angle of the servo arm. Many programs can set PWM values at different positions, for example, 500 corresponds to off, and 2500 corresponds to on. Find these two values and the lid will stop in the correct position. Remember to power on again and try again every time you finish changing the program.
After installation, you may encounter several problems: the servo buzzes but does not move, usually because the torque is insufficient or the power supply is not supplied; the cover shakes, which may be due to poor signal line contact; the response is slow, which may be due to the triggering distance of the sensor not being adjusted properly. The simplest way is to troubleshoot by module. First, use a program to control the servo separately. If it is normal, it is a problem with the sensor or logic.
There is another point that is easily overlooked: if the trash can is placed in a corner, the sensor may be blocked by the wall next to it, resulting in false triggering or no triggering. Before installation, put the trash can in the final use location and test it by simulating daily use scenarios. Only by handling these small details well can your smart trash can be used and enjoyed.
Seeing this, are you already itchy and want to give it a try? What kind of servo are you going to use to modify the trash can you have? Have you thought about where it will get stuck in advance?
Update Time：2026-03-25
Contact Kpower's product specialist to recommend suitable motor or gearbox for your product.
