Wastewater EM Flow Meter Hardware
Budget: $250 – $750 USD
I need the complete electronics hardware with softwarefor a compact electromagnetic flow-meter dedicated to wastewater lines in a water-management setting. The instrument must resolve low flow rates—0 to 10 m³/h—while coping with the higher conductivity, solids and variable temperature typically found in effluent pipes.
Scope of work
The job starts with selecting an appropriate excitation method (preferably low-frequency AC) and designing the analog front-end: coil driver, precision differential amplifier, adaptive filtering and a low-noise ADC. From there, the digital board should host a low-power MCU for signal processing, display handling and communications. I will eventually add my own mechanical tube and electrodes, so the PCB must fit within a 70 mm × 90 mm envelope and leave accessible pads for the electrode leads and coil.
Communications & outputs
• 4-20 mA loop, isolated
• RS-485 (Modbus RTU)
• Optional pulse output for totaliser integration
Power can be either 24 VDC loop-powered or 12 VDC local supply; let’s keep the design flexible enough to populate for either option.
Deliverables
• Schematic (Altium preferred, Gerber & BOM acceptable from any mainstream tool)
• Two-layer or four-layer PCB layout within the stated footprint
• Microcontroller firmware source with basic flow calculation and Modbus register map
• Test report showing linearity and repeatability across the 0–10 m³/h range in a simple bench loop (salt solution or tap water with added conductivity is fine)
Acceptance criteria
1. Stable zero when the pipe is empty.
2. ±1 % of reading from 1 % to 100 % of span.
3. Noise immunity proven with 50 Hz / 60 Hz common-mode injection at 1 Vpp.
Please keep component choices realistic for current supply chains and avoid parts with >26-week lead times. I will handle enclosure machining and final field calibration; the expectation here is a tested, reproducible electronics module ready to integrate.
Scope of work
The job starts with selecting an appropriate excitation method (preferably low-frequency AC) and designing the analog front-end: coil driver, precision differential amplifier, adaptive filtering and a low-noise ADC. From there, the digital board should host a low-power MCU for signal processing, display handling and communications. I will eventually add my own mechanical tube and electrodes, so the PCB must fit within a 70 mm × 90 mm envelope and leave accessible pads for the electrode leads and coil.
Communications & outputs
• 4-20 mA loop, isolated
• RS-485 (Modbus RTU)
• Optional pulse output for totaliser integration
Power can be either 24 VDC loop-powered or 12 VDC local supply; let’s keep the design flexible enough to populate for either option.
Deliverables
• Schematic (Altium preferred, Gerber & BOM acceptable from any mainstream tool)
• Two-layer or four-layer PCB layout within the stated footprint
• Microcontroller firmware source with basic flow calculation and Modbus register map
• Test report showing linearity and repeatability across the 0–10 m³/h range in a simple bench loop (salt solution or tap water with added conductivity is fine)
Acceptance criteria
1. Stable zero when the pipe is empty.
2. ±1 % of reading from 1 % to 100 % of span.
3. Noise immunity proven with 50 Hz / 60 Hz common-mode injection at 1 Vpp.
Please keep component choices realistic for current supply chains and avoid parts with >26-week lead times. I will handle enclosure machining and final field calibration; the expectation here is a tested, reproducible electronics module ready to integrate.