Vfd rat king

VFDRatKing

Introduction

Welcome to the VFDRatKing project! This custom-designed board is your solution for safely controlling your CNC spindle via a VFD using the Rodent Board by RatRig. Why, you ask? Because the RS485 implementation in FluidNC is as dependable as a wet napkin in a rainstorm. Seriously, when the Rodent loses connection, the spindle doesn't stop. That's a bit "iffy," wouldn't you say?

But that's not all! If you were trying to use the built-in relay in your VFD to control air, mist, or a water pump while hardwiring DCOM to FOR (Forward), you're probably having a bad time. This board is here to save the day by properly isolating signals and giving you precise control without these headaches. Designed by knight_rad.iant on Discord, this project brings a practical solution to your CNC workflow.

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How It Works

The board operates as an intermediary between the Rodent MCU (3.3V logic) and your spindle's VFD. Here's how the magic happens:

1. Logic Signal Conditioning:

   • The 3.3V logic signals from the Rodent are fed into a CD74HC4050E buffer IC.
   • This IC ensures the signals are conditioned and capable of driving higher current.

2. Optocoupler Isolation:

   • The conditioned signals pass through ILQ615-3 optocouplers to isolate the logic signals from the VFD control side.
   • This provides electrical isolation, keeping the Rodent and VFD grounds separate for safety and signal integrity.

3. Signal Translation:

   • The board outputs the control signals via a terminal block connector with the following pins:
     • DCOM: Isolated ground reference for the VFD.
     • OUT1, OUT2, OUT3, OUT4: Control signals that short to DCOM when corresponding inputs (INPUT1, INPUT2, INPUT3, INPUT4) are high.
   • The optocouplers ensure that these outputs are cleanly isolated from the Rodent Board's ground.

4. Connector Interface:

   • A JST-XH 6-pin connector provides easy integration with the Rodent MCU.

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Features

• Isolated Control Signals: Prevents electrical noise and interference between the Rodent MCU and the VFD.
• High-Current Drive Capability: The CD74HC4050E ensures the Rodent's 3.3V signals can reliably drive the optocouplers.
• User-Friendly Connections: JST-XH 6-pin input and terminal block output for straightforward wiring.
• All Through-Hole Components: Easy to solder, making it beginner-friendly.

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Schematic

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Bill of Materials (BOM)

• 1x ILQ615-3 Optocoupler DIP IC (x4)
• 1x CD74HC4050E IC
• 4x 470R Resistor (1/4 watt, 10% tolerance, through-hole)
• 1x 1uF Ceramic Capacitor (disc ceramic, 5.0mm pitch)
• 1x JST-XH 6-pin Connector
• 1x 5-terminal Block Connector (DCOM, OUT1, OUT2, OUT3, OUT4)
• 1x PCB (orderable via JLCPCB)

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PCB Ordering

The board can be ordered from JLCPCB using the provided Gerber files. Simply upload the files, select your options, and you'll have your custom PCB in no time.

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License

This project is shared under the Creative Commons License (CC BY-NC-ND): Non-Commercial, No Remix, Attribution Required. Contributions and modifications are welcome within these guidelines.

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Credits

Designed by knight_rad.iant on Discord. For questions or discussions, feel free to join the CNC community and share your thoughts!