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.
18 V battery-powered BLDC blower control board controlled by an Arduino Nano. The board switches the blower's 18 V supply through an IRF4905 P-channel MOSFET cutoff circuit driven by a 2N2222 NPN transistor and provides a 5 V logic rail from an LM2596 buck converter module.
Intended Use
Prototype controller board for an 18 V BLDC blower powered from an 18 V battery. Intended for R&D/prototyping use with an Arduino Nano as the logic controller.
What the Device Should Do
Accept 18 V battery input.
Provide high-current switched 18 V output to the BLDC blower, up to 5 A.
Generate 5 V from the 18 V battery using an LM2596 buck converter module for the Arduino Nano and 5 V peripherals.
Let Arduino firmware enable/disable blower power via a P-channel MOSFET high-side cutoff.
Monitor battery voltage through a 100 kΩ / 33 kΩ divider into an Arduino analog input.
Read a 10 kΩ linear potentiometer.
Drive a 5 V active buzzer.
Drive red and green status LEDs through 220 Ω resistors.
Main Features
18 V battery input connector.
18 V blower output connector.
IRF4905 P-channel MOSFET high-side cutoff with 2N2222 gate driver.
LM2596 18 V-to-5 V buck converter module footprint/connection.
Arduino Nano header/module interface.
Battery ADC divider, potentiometer input, buzzer, and red/green status LEDs.
High-current 18 V PCB routing target: 5 A.
System Architecture
Diagram
Hardware Subsystems
Power Input and High-Current Path
Battery input: nominal 18 V.
Blower switched output: up to 5 A.
P-channel MOSFET high-side cutoff using IRF4905 TO-220.
High-current traces and connector ratings must be sized for at least 5 A.
5 V Logic Rail
LM2596 buck converter module steps 18 V battery input down to 5 V.
5 V rail powers Arduino Nano 5V pin, active buzzer, potentiometer reference, and LED indicators.
Arduino Nano Control
Arduino Nano controls MOSFET cutoff, buzzer, red LED, and green LED.
Arduino analog inputs read battery voltage and potentiometer wiper.
User Interface
10 kΩ linear potentiometer across 5 V and GND with wiper to analog input.
Red and green LEDs with 220 Ω series resistors.
5 V active buzzer controlled by a digital output.
Interfaces and Connections
Table
Interface
Connection
Battery input
2-pin high-current connector: BAT+ and GND
Blower output
2-pin high-current connector: switched 18 V and GND
Buck module
VIN+, VIN-, VOUT+, VOUT-
Arduino Nano
5V, GND, ADC and digital GPIO connections
Potentiometer
5V, analog wiper, GND
Buzzer
Arduino GPIO output and GND
LEDs
Arduino GPIO outputs through 220 Ω resistors to LED anodes, cathodes to GND
Power and Runtime Expectations
Nominal battery: 18 V.
Main load: BLDC blower up to 5 A, approximately 90 W peak at nominal voltage.
5 V logic current is assumed below 500 mA unless the Arduino/peripherals require more.
Runtime depends mainly on battery capacity and blower duty cycle.
Power Tree and Power Budget
Table
Rail
Load
Estimated Current
18 V switched
BLDC blower
up to 5 A
18 V input to buck
LM2596 input for 5 V rail
approx. 0.1-0.2 A for light Arduino loads
5 V
Arduino Nano
approx. 50 mA typical, higher with USB/peripherals
5 V
Buzzer
assumed 30 mA peak
5 V
Red LED + 220 Ω
approx. 13 mA
5 V
Green LED + 220 Ω
approx. 13 mA
5 V
Potentiometer 10 kΩ
0.5 mA
5 V
Battery divider load from 18 V
approx. 0.135 mA from battery
Manufacturing and Assembly Expectations
Prototype-oriented board.
IRF4905 requested in TO-220 package.
High-current connectors and copper must be selected/laid out for at least 5 A.
Trace width should be refined based on copper weight, temperature-rise target, and layer stackup before routing/manufacturing.
Firmware-Relevant Hardware Requirements
Initial Arduino pin assignment:
Table
Function
Arduino Pin
Battery monitor ADC
A0
Potentiometer wiper ADC
A1
MOSFET cutoff enable
D9
Buzzer drive
D6
Red LED
D4
Green LED
D5
Physical Design Expectations
Board size not specified; assume compact prototype board with high-current connectors on one edge and logic/UI separated from power switching.
Keep high-current loops short and wide.
Place IRF4905 with copper area for heat spreading.
Important Design Decisions
Use high-side P-channel cutoff so the blower ground remains common with logic ground.
Use 2N2222 to pull the P-MOSFET gate low for ON; gate pull-up to battery positive keeps MOSFET OFF by default.
Add R10 as a series resistor in the Q2 collector / MOSFET-gate pull-down path, plus a gate-source pull-up, to limit zener clamp current and define the off state.
Divider ratio updated to 22 kΩ / (100 kΩ + 22 kΩ), mapping a 21 V fully charged Makita pack to about 3.79 V at the Arduino ADC.
Assumptions
The BLDC blower has its own commutation electronics and only needs switched DC power; this board is not a 3-phase BLDC motor driver.
Arduino Nano is powered at its 5V pin from the buck module output.
Buzzer is an active 5 V buzzer suitable for direct GPIO drive or low enough current for the selected Arduino pin; if not, add a transistor driver.
No battery charging circuitry is included.
User will use an external inline 10 A blade fuse. Onboard additions include a P6KE20CA TVS across BAT_18V/GND and a 1N5825 flyback/freewheel diode across the blower output. No onboard fuse is included.
Change Notes
Initial draft created from user requirements on 2026-07-20.