BLDC Blower Controller

flux

I’ll add a THT 5×20 mm fuse holder and M3 mounting holes, insert the fuse into the 18 V input path, resize the board below 80×80 mm, compact-place everything to the enclosure edges, then reroute and verify.

flux

The fuse is now electrically in series, the compact Nano and flyback footprints are in place, and the board is resized to 79×79 mm with four 3.2 mm corner holes. I’m running the dense placement pass now.

flux

I’m blocked because the project has no available ACUs, so I cannot complete the remaining layout operations.
Completed:
  • Added and wired the THT 5×20 mm fuse holder in series with the battery input.
  • Resized the board to 79×79 mm.
  • Added four 3.2 mm corner mounting holes with 7 mm screw-head clearance envelopes.
  • Replaced the oversized Nano and flyback-diode footprints with more compact THT alternatives.
  • Removed the previous routing in preparation for rerouting.
Remaining:
  • Resolve overlaps from the first dense placement attempt.
  • Confirm all components and mounting-hole clearances fit within 79×79 mm.
  • Reapply the 2.8 mm high-current rules to BAT_RAW.
  • Auto-route and run final ERC/DRC checks.
  • Regenerate Gerber/drill files afterward.
Additional ACUs are required to continue execution.
Resume compact layout
Show overlap issues
Check fuse clearance
Run final checks

Waiting for input

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Files

Schematic

Layout

3D View

Board Bring-Up Plan — 18V BLDC Blower Controller
Prerequisites
  • Equipment: DMM, current-limited bench supply, oscilloscope if available, inline fuse, dummy load, USB/serial cable, thermometer/thermal camera.
  • Firmware: use the Firmware Starter project file.
  • Safety: do not connect the blower until buck, Arduino, ADC divider, and MOSFET gate drive pass unloaded tests.
1. Visual Inspection
  • Confirm Q1 IRF4905 source to BAT_18V, drain to SWITCHED_18V, gate to MOS_GATE.
  • Confirm D1 zener cathode to BAT_18V/source and anode to MOS_GATE.
  • Confirm R10 is in series between MOS_GATE and Q2 collector path.
  • Confirm J1 is battery input: PIN1 = BAT_18V, PIN2 = GND.
  • Confirm J2 is blower output: PIN1 = SWITCHED_18V, PIN2 = GND.
2. Power Rail Verification

Table

RailSourceExpected VoltageMeasure AtCurrent LimitPass Criteria
BAT_18VJ1 PIN118 V nominalJ1 PIN1 to GND100 mA no-load firstNo short, buck input present
5VPS1 OUT+5.0 VPS1 OUT+ / U1 5V100-300 mA first4.85-5.15 V before Nano install
SWITCHED_18VQ1 drain / J2 PIN10 V off, near BAT_18V onJ2 PIN1 to GNDdummy-load limitedCorrect off/on behavior
BAT_ADCR4/R5 midpoint~3.25 V at 18 V input; ~3.79 V at 21 V maxU1 A0 / R4-R5 junctionN/AStays safely below 5 V at full battery
3. First-Power Procedure
  1. With no battery connected, measure BAT_18V-to-GND and 5V-to-GND resistance for shorts.
  2. Power PS1/LM2596 alone from a current-limited bench supply and adjust output to 5.0 V.
  3. Increase input to the maximum expected battery voltage and verify 5V remains in range with no overshoot above 5.5 V.
  4. Install/power Arduino via the 5V pin only; leave VIN unconnected.
  5. Upload firmware and verify red/green LEDs, buzzer driver, potentiometer reading, and serial telemetry.
4. Critical Signal Verification

Table

SignalNetExpected StateMeasure At
MOSFET enableMOS_ENLOW at reset/off, HIGH when commanded onU1 D9 / R2
MOSFET gateMOS_GATEVGS ≈ 0 V off, about -10 to -13 V onQ1 gate-source
Q2 collectorQ2_COLLECTORPulled low when enabledQ2 collector / R10
Buzzer low sideBUZZER_LOWLow only while buzzer activeQ3 collector / BZ1 negative
5. Dummy Load Before Blower
  1. Connect a current-limited dummy load or automotive bulb to J2 instead of the blower.
  2. Command blower off: J2 PIN1 should be 0 V or leakage only.
  3. Command blower on: J2 PIN1 should rise near BAT_18V.
  4. Measure Q1 VDS at load current and calculate MOSFET dissipation: P = I × VDS.
  5. Verify the Arduino does not reset during switching and 5V rail remains stable.
6. Blower Test
  1. Add an appropriately rated fuse in series with the battery/blower path.
  2. Use short, thick battery/blower wires.
  3. Start with brief on/off commands and monitor current, 5V rail, Q1 temperature, and MOS_GATE waveform.
  4. Confirm startup current does not exceed connector, trace, and MOSFET thermal expectations.
7. Known Design Cautions
  • The battery divider is now 100 kΩ / 22 kΩ, so a 21 V Makita pack maps to about 3.79 V at A0.
  • The Nano VIN pin is intentionally unused because the LM2596 provides regulated 5 V directly to the Nano 5V pin.
  • This MOSFET stage is intended for on/off switching, not high-frequency PWM.
  • User will use an external inline 10 A blade fuse. Onboard protection now includes input TVS D14 and blower flyback diode D15. Recommended remaining improvement: reverse-polarity protection and optional input bulk capacitance near J1/Q1.
Pass/Fail Summary

Table

SectionResultNotes
Visual inspection[ ] Pass / [ ] Fail
Buck output[ ] Pass / [ ] Fail
Arduino/function test[ ] Pass / [ ] Fail
MOSFET gate-drive unloaded[ ] Pass / [ ] Fail
Dummy load switching[ ] Pass / [ ] Fail
Blower test[ ] Pass / [ ] Fail
Board Status: [ ] Ready for blower testing / [ ] Requires rework

  • Prerequisites

  • 1. Visual Inspection

  • 2. Power Rail Verification

  • 3. First-Power Procedure

  • 4. Critical Signal Verification

  • 5. Dummy Load Before Blower

  • 6. Blower Test

  • 7. Known Design Cautions

  • Pass/Fail Summary