Vibration Motor PCB

There are numerous things the vibration motor is used for, such as video game controllers, smartphones, frequency testing, and massage guns, etc. This is a basic vibration motor circuit for educational and hobbyist purposes. It comes with a list of the required parts and tools, a checklist, a FreeCAD file, and a datasheet for theory/circuit analysis.

Note on red LED Behavior: The red LED () illuminates when the vibration motor () is subjected to external mechanical vibration, provided the slide switch () is switched on. This occurs because mechanical vibration generates back-EMF across the parallel motor branch, driving current through the red LED even when the potentiometer () is turned down. As well, Individual test results may vary slightly due to component tolerances and variations in motor resistance across other parts of the circuit. These minor differences are expected and will not impact the overall operation of the circuit.

Mechanical & Mounting Notes for 3D PCB Stand:

• PCB Spacers (35° Print Angle): Because these holes are 3D-printed at an angled orientation of 35°, slicing and layer stepping will cause an M4 hole to fit too loosely and an M3 hole to be too tight.
• Tapping Procedure:
• Model the spacer mounting holes with an undersized diameter of 3.5 mm (M3.5).
• Post-print, chase and thread the printed holes using an M3 × 0.5 HSS tap to create clean, secure threads for the M3 fasteners.

Tip: When tapping 3D-printed thermoplastic, turn the tap slowly with a drill and back it out periodically to clear plastic shavings. 

Breadboard/Prototype Instructions:

1.     Connect the third pin of the potentiometer to Ground with a 10 kΩ resistor.

2.     Attach the first pin of the potentiometer to the 2nd pin of the slide switch.

3.     Place the green LED and R1 in series with the 2nd pin of the switch and GND.

4.     Connect the 3rd pin of the switch to GND.

5.     Connect the 1st pin of the switch to the Positive rail.

6.     Test the switch to make sure the green LED turns on.

7.     Once you’ve completed the green LED sub-circuit, connect the 2nd pin of the potentiometer to the Gate pin of the MOSFET. This is what’ll gradually activate the vibration motor when the resistance drops. When the Gate threshold voltage reaches anywhere between 2 and 4 volts, the Drain pin will draw current to the red LED and the vibration motor. The lower the resistance of the potentiometer, the higher the Gate voltage.

8.     Place R3 in series with the red LED between the positive rail and the Drain pin of the MOSFET.

9.     Attach the blue wire of the motor to the Drain pin of the MOSFET and attach the red wire in series with R4 to the positive rail.

10. Connect R5 to the Gate and Source pins of the MOSFET. R5 is a 47 kΩ gate pull-down resistor. Because MOSFET gates are capacitive and prone to floating, R5 discharges residual gate charge to the GND, guaranteeing positive cutoff and preventing unexpected motor activation when the potentiometer is turned OFF.

11. Attach the aluminum heatsink to the MOSFET with the screw, nut, and washer. Over time, the MOSFET can get hot, whereas the heatsink will help dissipate the heat. Once you attach the heatsink to the MOSFET, make it snug.

12. Insert the capacitor in parallel with the vibration motor to suppress any EMI and electrical noise.

13. Insert D4 in parallel with the motor as a flyback diode. This is to ensure that no harmful voltage spikes will cause any component damage when the power is turned OFF.

14. Turn the power supply on and make sure it’s set to 4.5 V.

15. Flip the slide switch to turn the green LED on.

16. Slowly rotate the potentiometer to gradually increase the brightness of the red LED and the vibration of the motor.

Vibration Motor Checklist

Slide Switch Circuit

1.     Pin 3 is connected to GND. ☒

2.     Pin 1 is connected to the positive rail. ☒

3.     Pin 2 is connected to the potentiometer and the green LED. ☒

Red LED Circuit

4.     Series Resistors(Ω): 220. ☒

5.     The LED anode (+) is connected to the positive rail.☒

6.     The LED cathode (-) is connected to R3.☒

7.     R3 is connected to the drain of the MOSFET. ☒

Green LED Circuit

8.     Series Resistors(Ω): 220. ☒

9.     The LED anode (+) is connected to pin 2 of the switch.☒

10. The LED cathode (-) is connected to R1. ☒

Potentiometer Circuit

1.     The positive terminal is connected to pin 2 of the switch. ☒

2.     The negative terminal is connected to R2. ☒

3.     R2 is connected to GND. ☒

4.     The middle terminal is connected to the gate of the MOSFET. ☒

MOSFET Circuit

1.     The gate is connected to the middle terminal of the potentiometer. ☒

2.     The drain is connected to the negative terminal of the motor and R3. ☒

3.     The Source is connected to the ground. ☒

4.     R4 (47 Ω) is connected to the positive terminal of the motor and the positive rail. ☒

5.     R5(47000 Ω) is connected to the Gate pin and the Source pin. ☒

6.     D3 is in parallel with the motor, with the cathode connected to the positive side and the anode connected to the negative side. ☒

7.     C1 is in parallel with the motor. ☒

Whole Circuit

11. Negative and Positive loops are completed. ☒

12. Copper is filled on B.Cu. ☒

13. Copper is filled on F.Cu. ☒

14. No islands. ☒

15. Thermal Pads. ☒

16. Horizontal distance between PCB mount holes is 65 mm. ☒

17. Vertical distance between PCB mount holes is 95 mm. ☒

18. PCB mount hole radius equals 1.6mm. ☒

19. Healthy gap between blue layer and red traces. ☒

20. Labels are accurate. ☒

21. DRC:

a.    Refill all before performing DRC. ☒

Circuit Test

22. The red LED responds to the potentiometer in correspondence with the motor. ☒

23. The potentiometer adjusts the current. ☒

24. The switch connects and disconnects the circuit. ☒