The AOS 3.5 frame paired with the GEP-F722 flight controller is a favorite among drone enthusiasts building high-performance, compact FPV drones. These components offer excellent functionality and performance, but achieving a reliable build requires careful planning and precise soldering. In this article, we’ll cover a 1,900-word detailed guide on soldering the GEP-f722 Soldering flight controller while ensuring it fits perfectly in the AOS 3.5 frame.
Understanding the Components
Before diving into soldering, it’s crucial to familiarize yourself with the AOS 3.5 frame and the GEP-F722 flight controller. Knowing their specifications and features will help you plan the assembly effectively.
The AOS 3.5 Frame
The GEP-f722 Soldering frame is designed for sub-250g FPV drones, making it ideal for pilots who want a lightweight yet durable structure. Its carbon fiber construction ensures strength while keeping the frame lightweight. The key highlights of the AOS 3.5 frame include:
- Optimized Design: Its layout minimizes frame resonance, reducing vibrations and improving flight performance.
- Compact Size: A 3.5-inch propeller compatibility offers a balance between agility and stability.
- Versatile Mounting: Multiple mounting options for flight controllers, ESCs, and other peripherals allow for a neat assembly.
The GEP-F722 Flight Controller
The GEP-F722 flight controller is a versatile and feature-packed component designed for demanding FPV builds. It boasts:
- F7 Processor: Supports advanced features and protocols like Betaflight and INAV.
- Integrated OSD: Simplifies video feed customization with on-screen telemetry.
- Multiple UARTs: Enables connection of various peripherals such as GPS modules, receivers, and LEDs.
- Solder-Friendly Layout: Clearly labeled pads for ESCs, motors, and accessories, making it beginner-friendly.
Also read: B12 Raider Amp
Tools and Materials Needed for Soldering
Soldering the GEP-f722 Soldering flight controller requires the right tools and materials to ensure a clean and durable build. Here’s what you’ll need:
Essential Tools
- Soldering Iron: A temperature-controlled soldering iron with a fine tip (recommended temperature: 350–400°C).
- Solder Wire: Choose 63/37 or 60/40 leaded solder for better flow and ease of use.
- Flux: Essential for improving solder adhesion and reducing oxidation.
- Desoldering Wick: For removing excess solder or correcting mistakes.
- Tweezers: To hold small components or wires in place.
- Magnifying Glass or Microscope: Ensures precision when working with small pads.
- Multimeter: To test continuity and check for short circuits.
Additional Materials
- Heat Shrink Tubing: For insulating exposed wires.
- Electrical Tape: To secure wires and prevent accidental contact.
- Isopropyl Alcohol: For cleaning solder pads and wires.
- Smoke Stopper: To safely power up the build for the first time.
- Low-ESR Capacitor: Helps filter voltage spikes and reduce electrical noise.
Preparing for Soldering
Proper preparation is essential for a successful soldering process GEP-f722 Soldering. Follow these steps to set up your workspace and components.
Step 1: Plan the Layout
- Assemble the AOS 3.5 frame without attaching the electronics to visualize the layout.
- Decide on the placement of components, including the flight controller, ESC, VTX, camera, and receiver.
- Route wires efficiently to minimize clutter and avoid signal interference.
Step 2: Tin the Pads and Wires
Tinning is the process of pre-applying solder to the pads and wire ends. This step improves solder adhesion and simplifies the connection process.
- Set your soldering iron to 350–400°C.
- Apply a small amount of flux to the solder pads on the GEP-F722 flight controller.
- Melt a thin layer of solder onto each pad.
- Pre-tin the ends of all wires you plan to solder, ensuring the solder covers the stripped portion evenly.
Step 3: Clean the Work Area
Ensure your workspace and components are clean to prevent contamination:
- Wipe the solder pads and wires with isopropyl alcohol to remove any grease or debris.
- Organize your tools for easy access during soldering.
Step-by-Step Soldering Guide
With the preparation complete, it’s time to solder the components to the GEP-f722 Soldering flight controller. Follow these steps to achieve clean and reliable connections.
Step 1: Solder the ESC Connections
- Motor Wires:
- Connect the motor wires from the 4-in-1 ESC to the motor output pads on the flight controller.
- Ensure the order matches your intended motor configuration in Betaflight.
- Signal Wires:
- Solder the ESC signal wire to the appropriate pad on the GEP-F722.
- Connect the ground and telemetry wires if supported by your ESC.
- Double-Check Alignment:
- Verify that each wire is correctly placed to avoid reversed connections.
Step 2: Connect Power and Battery Leads
- Power Input Pads:
- Solder the positive (VBAT) and ground wires to the main power input pads on the flight controller.
- Add a Capacitor:
- Attach a low-ESR capacitor across the power pads to filter out voltage spikes and electrical noise.
- Secure the Wires:
- Use heat shrink tubing to insulate the solder joints.
Step 3: Receiver Wiring
- UART Pads:
- Connect the signal (RX and TX) wires from your receiver to the designated UART pads on the flight controller.
- Power the Receiver:
- Solder the receiver’s power and ground wires to the 5V and GND pads on the GEP-f722 Soldering.
- Check Protocol Compatibility:
- Ensure your receiver protocol (e.g., SBUS, Crossfire) matches the configuration in Betaflight.
Step 4: VTX and Camera Connections
- Camera Wiring:
- Solder the camera’s video signal wire to the CAM pad.
- Connect the power and ground wires to the designated pads on the flight controller.
- VTX Wiring:
- Solder the video input wire from the VTX to the VTX pad on the flight controller.
- Connect the power, ground, and SmartAudio/IRC Tramp wires for remote VTX control.
Step 5: Additional Peripherals
- LEDs:
- If using addressable LEDs, solder them to the LED pad and configure them in Betaflight.
- GPS Module:
- Connect the GPS module’s RX and TX wires to a free UART and power it through the 5V and ground pads.
- Buzzer:
- Solder the buzzer’s signal and power wires to the designated pads for audio feedback.

Testing and Verification
Once all connections are complete, it’s crucial to test your work before powering up the GEP-f722 Soldering flight controller.
Step 1: Visual Inspection
Carefully inspect all solder joints:
- Look for cold solder joints (dull or lumpy connections). Reflow them if necessary.
- Check for accidental solder bridges between adjacent pads.
Step 2: Continuity Test
Use a multimeter to check for continuity:
- Verify there are no short circuits between the power and ground pads.
- Check the connections for proper conductivity.
Step 3: First Power-Up
- Use a smoke stopper to safely power up the flight controller for the first time.
- Observe for any signs of overheating or malfunction.
Step 4: Firmware Configuration
- Connect the GEP-f722 Soldering to your computer using a USB cable.
- Open Betaflight Configurator to flash the appropriate firmware and configure settings.
- Test motor outputs, receiver inputs, and peripheral functionality.
Tips for Successful Soldering
To ensure your build is reliable and efficient, keep these soldering tips in mind:
Use Quality Materials
- Invest in a high-quality soldering iron and leaded solder for better results.
- Use a low-ESR capacitor to stabilize the power supply.
Practice Precision
- Work in a well-lit area to see small details clearly.
- Use magnifying tools if necessary.
Take Your Time
- Avoid rushing the soldering process to prevent mistakes.
- Double-check each connection before moving to the next step.
Clean As You Go
- Regularly clean the soldering iron tip with a damp sponge to maintain performance.
- Remove excess flux residue using isopropyl alcohol.
Conclusion
Soldering the GEP-f722 Soldering flight controller for the AOS 3.5 frame may seem daunting, but with careful preparation and attention to detail, it can be a straightforward and rewarding process. By following this guide, you’ll create a reliable, high-performing FPV drone that’s ready to take on any challenge.
Whether you’re a seasoned builder or a beginner, mastering these soldering techniques will elevate your skills and ensure the success of your FPV builds. Happy flying!