• Status: Draft schematic in progress.
• Companion supply board for the 96-Well Electrode Plate.
• Converts one AAA cell into a rotary-selectable, current-limited low-voltage electrode drive source.

• Prototype/validation accessory for electrochemical plate testing.
• Plugs directly into the plate’s three SMB connectors for internal 2-electrode operation.
• Can alternatively route the plate SMBs to external WE/RE/CE binding posts for a potentiostat.

• Accept one AAA alkaline cell across 0.9–1.6 V usable range.
• Generate a regulated output selectable from 0.2 V to 1.4 V in 0.1 V steps.
• Limit internal-source output current to approximately 10 mA.
• Light an indicator only when actual load current is detected.
• Route SMB_WE/SMB_RE/SMB_CE either to the internal source or to external binding posts, never both.

• AAA holder, power switch, and reverse-polarity protection.
• Low-startup boost converter to a 3.3 V rail.
• 2.048 V precision shunt reference.
• 16-position hexadecimal rotary selector plus 16:1 analog multiplexer selecting ladder taps.
• Zero-drift op-amp output regulator stage with high-side P-MOS pass element.
• Sense resistor, amplified current sense, active current-limit clamp, and load-detect LED.
• Three SMB outputs and three external electrode terminals.

Diagram

• Power input: one AAA cell, slide power switch, P-channel MOSFET reverse protection.
• Boost rail: 3.3 V generated from 0.9–1.6 V battery input; sized for 10 mA output plus analog overhead.
• Reference and selection: 2.048 V LM4040 shunt reference, 20 µA ladder, ADG706 mux selected by rotary hex code.
• Output regulator: op-amp controls a high-side P-MOS pass element; output feedback is taken before the INT/EXT routing switch.
• Current sensing: 33 Ω high-side/output-side resistor, gain-5 differential amplifier.
• Current limit: comparator threshold set for about 9.99 mA; current-limit comparator pulls the pass FET gate off through a PNP clamp.
• Load detect: comparator threshold set for about 49.7 µA; LED current is sourced from 3.3 V, not from the electrode output.
• Routing: 3PDT switch keeps SMB_RE independent in EXT mode and isolates the internal source from external binding posts.

• BT1: one AAA cell.
• SMB_WE: internal mode = +VOUT; external mode = WE binding post.
• SMB_RE: internal mode = GND; external mode = RE binding post, independent of CE.
• SMB_CE: internal mode = GND; external mode = CE binding post.
• Rotary switch: positions 0 and 14–15 park at 0 V/off; positions 1–13 select 0.2–1.4 V.

• Normal plate current is expected around 1 mA total.
• Worst-case regulated output limit is approximately 10 mA.
• LED current is intentionally low, targeting about 100 µA so the indicator does not dominate AAA runtime.

• SMD professional/prototype assembly unless user later requests hand-solder-only substitutions.
• 2-layer FR4 expected to be sufficient; layout should isolate boost switching currents from the analog output/reference area.
• Silkscreen must include voltage legend, INT/EXT labels, WE/RE/CE labels, and battery polarity.

• No firmware, MCU, or programmable logic.

• SMB connectors must mate directly to the 96-Well Electrode Plate and use Molex 73100-series geometry.
• Binding/turret terminals must be accessible to crocodile clips.
• Rotary selector and INT/EXT switch must be human-accessible.

• Architecture remains boost → precision reference/ladder → op-amp-controlled pass regulator.
• Pushback incorporated: the op-amp will not directly source the load; it controls a pass FET with sense resistor inside the local regulation loop.
• The 16-position coded rotary requires an analog mux; this keeps the no-firmware requirement while avoiding an unavailable true SP16T library part.
• Unused rotary positions are parked at 0 V/off.

• The plate’s SMB mating choice corresponds to Molex 0731000105 / 73100-series geometry; the Flux library description appears inconsistent but the MPN and datasheet match the requested family.
• SMB shell pins remain isolated/not used unless the plate mechanical/electrical requirement later specifies otherwise.
• External binding posts are implemented as robust PCB screw/turret-style terminals if exact binding-post parts are unavailable.

• Initial specification created from the attached user requirements and schematic architecture review.