Precision Analog/PCB Engineer for Industrial Sensing

We're an early-stage hardware company building a precision monitoring device that tracks the electrical health of liquid-cooled equipment racks in high-power environments. The board is a multi-channel analog sensing front-end with an MCU and Ethernet that streams telemetry to our backend. The analog architecture is already designed and the hard measurement problems are solved. We need an experienced engineer to take it from roughly 60 percent schematic complete to a manufacturable board: finish the design, lay it out, and document it. Please read this before bidding: the prior engineer delivered the schematics as PDFs only — there are no native Altium source files. So the job begins by rebuilding the existing schematics in native Altium from the PDFs we provide, and you own the source files going forward. We're stating this up front so your bid is accurate. What already exists: Four schematic sheets (sensing, power, MCU/Ethernet), roughly two-thirds complete, delivered as PDFs A precision analog front-end designed and validated on paper — built around a 24-bit delta-sigma ADC, low-offset precision op-amps, a precision voltage reference, Hall-effect current sensors, an impedance-analyzer IC, a digital isolator, and a temperature-compensation channel (exact part numbers shared under NDA) Differential current, impedance spectroscopy, conductivity, and temperature sensing channels What we need you to deliver: Rebuild the existing schematic sheets in native Altium from the provided PDFs Finalize one open design decision on the conductivity-sensing channel (discrete precision op-amp approach vs. an integrated module) Design and integrate industrial-grade protection for an 800V fault scenario across the front-end — the current design only has consumer-grade ESD protection Full PCB layout: mixed-signal, multilayer, with proper analog/digital partitioning, grounding, and attention to the precision current-sense path Formal BOM with sourcing and recommended alternates Firmware block diagram (architecture level — sensor init, sampling, data packaging, Ethernet transport; not full firmware implementation) The key engineering challenge: the hardest part of this job is item 3 — protecting a milliamp-resolution differential current-sense front-end against an 800V fault event without degrading measurement accuracy. If that problem sounds interesting to you rather than intimidating, you're the person we're looking for. Skills we're looking for: Altium Designer — schematic capture and PCB layout Precision analog front-end design (low-offset op-amps, 24-bit delta-sigma ADCs, voltage references) Mixed-signal multilayer PCB layout — analog/digital partitioning, grounding, signal integrity High-voltage isolation and circuit protection (creepage/clearance, isolation barriers, transient/TVS strategy) Ethernet PHY/MAC layout Familiarity with industrial safety standards for electronic measurement and test equipment a plus Bonus: experience with current/leakage sensing or electrical fault detection How we'll work: Fixed-price, milestone-based, funded into escrow per milestone We start with a small paid trial milestone — recreate one provided schematic sheet in Altium — so we can confirm fit and tooling before committing the full scope NDA required before any files are shared To apply, please answer these three questions: Will you personally be doing the design work, or would it be handled by a team? Either is fine — we just want a clear picture of who we'd be working with. Share two or three examples of mixed-signal boards you've designed that involved high-voltage isolation and precision analog measurement. Briefly: how would you protect a milliamp-resolution differential current-sense front-end from an 800V fault event without degrading its measurement accuracy? We read every application and reply to serious ones quickly. Thanks for taking a look.