DIY Automatic Water Pump Controller with Dry-Run Protection | Complete KiCad 10 & ngspice Tutorial

In this comprehensive hardware engineering tutorial, we design, simulate, and lay out a professional 12V Solid-State Automatic Water Pump Controller with Dry-Run Lockout Protection from scratch using KiCad 10 and ngspice. Most common water pump motor failures occur when the underground reservoir or source tank runs dry, causing the pump to run without water and burn out its impeller or motor windings. This circuit uses pure CMOS logic (CD40106B, CD4002B, CD4001B) and an IRF9540N P-channel Power MOSFET to monitor water levels, automatically cycle the pump between LOW and HIGH thresholds, and instantly lock out the system if the source runs dry until manually reset. ⚡ PROJECT HIGHLIGHTS: 100% Solid-State: Pure CMOS logic — NO microcontrollers, NO firmware bugs, NO software lockups. Dry-Run Lockout: Immediate motor shutdown if source tank water falls below safety threshold. Hysteresis & Debounce: RC low-pass filters + Schmitt triggers eliminate mechanical contact bounce and water ripple. High-Side MOSFET Switch: IRF9540N P-MOSFET delivers clean ground-referenced switching with low Rds(on). Comprehensive Protection: TVS transient clamp, reverse-polarity P-FET, freewheeling inductive clamp, logic decoupling. Professional 2-Layer PCB: Complete track routing, ground pours, Net Classes (0.50mm / 0.75mm), and DRC verification. ⏱️ TIMESTAMPS & CHAPTERS: 00:00 - Introduction & 12V Water Pump Controller Overview 00:54 - Design Specifications & Engineering Requirements 01:34 - System Block Diagram & Control Logic Truth Table 02:49 - KiCad 10 Project Setup & Schematic Editor Workflow 04:36 - Section 1: 12V Power Input & Reverse-Polarity Protection 06:40 - Section 2: Stainless Steel Level Sensor Conditioning & Debounce 08:18 - Section 3: CMOS Combinational & Latching Logic (CD4000 Series) 09:59 - Section 4: Power MOSFET High-Side Gate Drive & Relay Output 11:21 - Section 5: Status Indicator LEDs (RUN, FAULT, SOURCE OK) 12:12 - Section 6: Electrical Rules Check (ERC) & Netlist Verification 12:57 - Section 7: ngspice Transient Simulation & Circuit Analysis 15:10 - Section 8: KiCad 10 PCB Layout, Net Classes, Track Routing & 3D Viewer 18:03 - Summary, Design Files & Conclusion 🛠️ CIRCUIT SPECIFICATIONS: Operating Supply: 12V DC nominal (10V to 14.5V) Motor Switching Capacity: Up to 10A Continuous (IRF9540N P-MOSFET with Heatsink) Sensor Inputs: Overhead Tank HIGH, Overhead Tank LOW, Underground SOURCE Logic ICs: CD40106B (Hex Schmitt Inverter), CD4002B (Dual 4-Input NOR), CD4001B (Quad 2-Input NOR) Quiescent Standby Current: 15 mA 🔔 Subscribe to Engineering & Tech Lab for weekly hands-on electrical engineering, KiCad PCB layout, and LTspice/ngspice simulation tutorials! #KiCad #KiCad10 #WaterPumpController #CircuitDesign #ElectronicsEngineering #PCBDesign #ngspice #MOSFET #HardwareEngineering