Mini Racecar PCB

A custom electronics board for a 2WD, IR-controlled differential-drive robot vehicle, designed in KiCad.

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Overview

Form factor	< 100 mm × 100 mm
Fabrication	2-layer rigid FR-4, via Robotistan PCB Service
Battery input	2S–6S LiPo (4.5 V – 40 V input range)
Logic compatibility	Any 5 V-based microcontroller
Motor support	Low-reduction 3–6 V TT motors, 150 mA (no load) – 1.5 A (stall)

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Power & Drive Architecture

The board combines a buck-style power stage (inductor + Schottky + electrolytic caps) to step the LiPo input down for logic rails, and a dual full H-bridge built from discrete IRF540N MOSFETs (driven via IR2104 half-bridge drivers) to independently control two DC motors for differential steering. IR receiver pins bring in the remote-control signal.

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Bill of Materials

Power Stage

Ref	Value	Notes
L1	33 µH	Radial inductor, Fastron 07HCP
D1	5 A / 100 V Schottky	Buck rectifier
Q — power switching	8× IRF540N	TO-220, vertical
IC — gate drivers	4× IR2104	DIP-8, half-bridge driver

Capacitors

Ref	Value	Package
C1	100 µF / 16 V	Electrolytic
C2	220 µF / 16 V	Electrolytic
C9	470 µF / 16 V	Electrolytic
C12	470 µF / 16 V	Electrolytic
C7, C13	1 µF	SMD 1206
C8, C15	10 µF	SMD 1206
C3, C4, C11, C14	0.47 µF	SMD 0805
C5, C6, C10, C16	0.1 µF	SMD 0805

Diodes

Ref	Value	Package
D1	5 A / 100 V Schottky	—
D2, D3, D4, D5, D6, D10, D11, D12	1N4148	THT DO-35, 7.62 mm
D7, D8, D9, D13	MURS260	SMD, SMB

MOSFETs & Gate Drive

Ref	Part	Package
Q1–Q8	IRF540N	TO-220-3, vertical
IR2104 ×4	Half-bridge driver	DIP-8

Resistors

Ref	Value (Ω)	Package
R1, R2, R3, R4, R6, R7, R9, R10	10	SMD 0805
R5, R8	0.1 (current sense)	SMD 0805

Connectors

Ref	Type	Footprint
Load1, Load2, Input	2-pin terminal block	MaiXu MX126-5.0-02P, 5.00 mm pitch
IR_pins	3-pin header	2.54 mm pin header, vertical
IR_pins1	Custom	—

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Tooling

Designed entirely in KiCad.