A simple remote-controlled gate opening and closing system.
| Pcs | Item | Notes/Specs |
|---|---|---|
| 2 | Linear Actuator | 12V 400 N 25mm/s. Controls the opening/closing of the gate |
| 1 | Power Supply | 220V AC - 12V DC, 16A. Match this based on your actuator specs |
| 1 | NodeMCU ESP8266 | Any MCU will do as long as it has 3 GPIO pins and 1 ADC pin |
| 1 | 2-Channel Relay Module | Will be controlled by NodeMCU. Will control the auto relays |
| 2 | Automotive Relay | Controls the Linear Actuators |
| 1 | Buck Converter | 12V to 5V. Powers the MCU and Relay Module |
| 1 | Remote Control Module | 1 Channel only needed |
| 1 | Project Box | Must be weatherproof |
The circuit looks complex but that's because I didn't arrange the components properly. I marked the control circuit as blue and the driver circuit as red.
The driver circuit is inspired by an H-Bridge Circuit Configuration.
The good thing with using 2 relays instead of 4 is that it will be impossible to have a state where both of the left or right side of the switches are active, intitiating a short circuit and damaging components in the process.
The control circuit is made up of:
- Buck Converter - this steps down the 12V to 5V which will power the rest of the control circuit
- Current Sensor - this is what is used to indirectly detect obstacles during opening or closing of the gate
- Remote Control Module - this is what will receive the remote button click and trigger the opening and closing of the gate
- 2 Channel Relay - this is what will control driver relays
- NodeMCU v3 Lolin - this will control the remote of the gate and ensure the proper logic of the circuit
Originally, I was planning to not use the NodeMCU at all as the driver circuit can directly be controlled using the relay found inside the Remote Control Module. However, I went against this as I was too lazy to find a way to measure the current passing through the linear actuators. It's also an indirect way of detecting whether there are obstacles stopping the opening or closing of the gate. I also wanted to disengage the driver relays entirely after one minute of inactivity so that it will wear out less often.
Improvements that can be made:
- GPIO12 is an interrupt relay. This means that I can put the NodeMCU to sleep after one minute to increase its life.
- Find an analog way of detecting current overload of the actuators so that I can get rid of the current sensor.
- The linear actuators that I bought is only rated IP54, which means that although it can handle rain and dust, it's not entirely dustproof and waterproof.
- I am well aware that I am shorting VIN to VU. This was an oversight when I was soldering the circuit. Seems like you need to power the MCU using VU. The 5V rail was attached to VIN but VIN needs more than 5V so that it can step it down to 5(?) or 3V3(?). I did a quick fix of this by shorting VIN and VU with a wire.
This is the constructed circuit diagram inside the project box.
This is what the gate looks like with the linear actuators attached to it. Thanks to dad for the assistance with drilling and attaching the anchors to the posts.
- Schematic was created using circuit-diagram.org
- NodeMCU Pinout