Simulacra

simulacra

KiCAD 10 hardware project that converts the 0-30V output of a Wanptek GPS305D bench supply into a symmetric split (virtual-ground) supply. Whatever voltage the GPS305D is set to, the output is that voltage's midpoint as the new 0V reference — e.g. 8V in gives ±4V out, 30V in gives ±15V out. The split point is ratiometric, not fixed, so no per-voltage tuning is needed.

How it works

• J1 (screw terminal) brings in the GPS305D's raw 0-30V output. The raw Positive/Negative pair is distributed unchanged to all three child sheets from the root schematic.
• Rail Splitter — R3/R4 (100k each) form a resistor divider from Positive/Negative down to the Common tap. This divider is what makes the split track the source voltage automatically, standing in for a dedicated rail-splitter IC. C1 (0.33µF, tap-to-Negative) filters ripple at the tap.
• Buffer — U2 (TL071) drives Buffered from the Common tap. Its inverting input is wired to Feedback, looped back from the Transistors sheet's Ground output rather than tied to its own output — this closes the loop around the whole push-pull stage, correcting for Q1/Q2's Vbe drops so the final virtual-ground node tracks Common, not just U2's output.
• Transistors — Q1 (BD139, NPN) and Q2 (BD140, PNP) form a complementary emitter-follower current-boost stage, biased by R1/R2 (4.7k) and D1/D2 (1N4148). Output is Ground — the actual virtual-ground node, sensed by the buffer's feedback.

Project structure

• simulacra.kicad_pro / .kicad_prl — project settings (ERC severities, net classes, BOM format)
• simulacra.kicad_sch — root schematic; distributes rails to the child sheets
• splitter.kicad_sch — "Rail Splitter" child sheet
• buffer.kicad_sch — "Buffer" child sheet
• transistors.kicad_sch — "Transistors" child sheet
• simulacra.kicad_pcb — PCB layout
• vendor/ — third-party library files used by this design

Status

PCB layout is in progress: footprints are placed, no traces routed yet.