Test and measurement circuits for a physics lab bench, built bottom-up from a bootstrap PSU through the tiers laid out in docs/general_purpose_circuit_dependency.md. Spacetime research — experiments aimed at faster-than-light travel, with no fixed commitment to any one specific theory or approach — is the current driving objective and gets its own tier graph in docs/spacetime_circuits_dependency.md, but the general-purpose foundation underneath it — PSU tiers, protection, safety monitoring, signal conditioning, measurement tools — isn't specific to that goal and is meant to be useful on its own.
Each circuit gets its own top-level folder with a SPICE netlist, a
generated schematic, and a breadboard wiring guide. Power supplies are
grouped under power_supplies/; measurement/test tools are grouped under
measurement_tools/; signal-conditioning building blocks (references,
amplifiers, sensor front-ends) are grouped under signal_conditioning/;
timing/waveform generators are grouped under oscillators/; safety
monitoring circuits are grouped under safety/; current/voltage
protection circuits are grouped under protection/; other circuit
categories get their own top-level folders as they're built.
Each project can render a schematic.png from its .spice netlist.
schematic.png is not committed (see .gitignore) — it's a build
artifact, regenerated on demand:
# from the repo root
python tools/spice_to_schematic.py oscillators/ne555_astable/ne555_astable.spiceOutput is written as schematic.png in the same directory as the .spice
file. tools/spice_to_schematic.py uses schemdraw to parse SPICE R,
C, V, and D elements and render a schematic image.
Every circuit folder has an ngspice .spice netlist. Run with ngspice -b
to predict voltages and currents before building.
# from the repo root
ngspice -b measurement_tools/fuse_test_voltmeter/fuse_test_voltmeter.spice
ngspice -b measurement_tools/cd4066_switch_tester/cd4066_switch_tester.spice
ngspice -b power_supplies/psu_pico_rail/psu_pico_rail.spice
ngspice -b power_supplies/psu_ultralow_v1/psu_ultralow_v1.spice
ngspice -b power_supplies/psu_low_v2/psu_low_v2.spice
ngspice -b power_supplies/psu_3xaa/psu_3xaa.spice
ngspice -b power_supplies/psu_4xaa/psu_4xaa.spice
ngspice -b power_supplies/psu_medlow_usbc/psu_medlow_usbc.spice
ngspice -b signal_conditioning/voltage_reference_lm358/voltage_reference_lm358.spice
ngspice -b signal_conditioning/transimpedance_amplifier/transimpedance_amplifier.spice
ngspice -b oscillators/ne555_astable/ne555_astable.spice
ngspice -b measurement_tools/capacitance_bridge/capacitance_bridge.spice
ngspice -b signal_conditioning/electric_field_probe/electric_field_probe.spice
ngspice -b signal_conditioning/charge_amplifier/charge_amplifier.spice
ngspice -b safety/thermal_monitor/thermal_monitor.spice
ngspice -b signal_conditioning/phase_detector/phase_detector.spice
ngspice -b protection/active_current_limiter/active_current_limiter.spice
ngspice -b measurement_tools/inductance_bridge/inductance_bridge.spice
ngspice -b signal_conditioning/accelerometer_interface/accelerometer_interface.spice
ngspice -b oscillators/vibration_driver/vibration_driver.spice
ngspice -b signal_conditioning/adc_ads1115/adc_ads1115.spice
ngspice -b signal_conditioning/lockin_amplifier/lockin_amplifier.spice
ngspice -b signal_conditioning/optical_shadow_readout/optical_shadow_readout.spice
ngspice -b signal_conditioning/hall_amplifier/hall_amplifier.spice
ngspice -b measurement_tools/frequency_counter/frequency_counter.spice
ngspice -b safety/overvoltage_monitor/overvoltage_monitor.spiceRun from the repo root. Each netlist prints an operating point at its nominal load, then sweeps the load resistor to show the V/I curve.
oscillators/ne555_astable/ (and any future circuit using a behavioral
macromodel rather than plain R/C/V/D elements) prints gmin/source-
stepping warnings during startup — expected for that kind of model, not a
sign the result is wrong; see that circuit's own README § Simulate for
why.
Printing an operating point documents what a circuit should do; it
doesn't check it. Every circuit folder also has a smoke_test.py that
runs its netlist and asserts against real thresholds: no node exceeding a
part's safe voltage, no resistor dissipating more than its rated wattage
(where the resistor is an actual physical part — some netlists use Rload
purely as a simulated stand-in for whatever gets attached later, which
isn't a smoke risk on its own), and a functional check that the circuit
actually does what it claims (a divider ratio within tolerance, a
buffered reference holding steady under load, a switch reading
unambiguously different when open vs. closed). tools/ngspice_runner.py
holds the shared ngspice-invocation/parsing logic every smoke_test.py
reuses.
# from the repo root
python measurement_tools/cd4066_switch_tester/smoke_test.py
python measurement_tools/fuse_test_voltmeter/smoke_test.py
python power_supplies/psu_low_v2/smoke_test.py
python power_supplies/psu_3xaa/smoke_test.py
python power_supplies/psu_4xaa/smoke_test.py
python power_supplies/psu_medlow_usbc/smoke_test.py
python power_supplies/psu_pico_rail/smoke_test.py
python power_supplies/psu_ultralow_v1/smoke_test.py
python signal_conditioning/voltage_reference_lm358/smoke_test.py
python signal_conditioning/transimpedance_amplifier/smoke_test.py
python oscillators/ne555_astable/smoke_test.py
python measurement_tools/capacitance_bridge/smoke_test.py
python signal_conditioning/electric_field_probe/smoke_test.py
python signal_conditioning/charge_amplifier/smoke_test.py
python safety/thermal_monitor/smoke_test.py
python signal_conditioning/phase_detector/smoke_test.py
python protection/active_current_limiter/smoke_test.py
python measurement_tools/inductance_bridge/smoke_test.py
python signal_conditioning/accelerometer_interface/smoke_test.py
python measurement_tools/logic_analyzer_check/smoke_test.py
python oscillators/vibration_driver/smoke_test.py
python signal_conditioning/adc_ads1115/smoke_test.py
python signal_conditioning/lockin_amplifier/smoke_test.py
python signal_conditioning/optical_shadow_readout/smoke_test.py
python signal_conditioning/hall_amplifier/smoke_test.py
python measurement_tools/frequency_counter/smoke_test.py
python measurement_tools/signal_generator_r2r/smoke_test.py
python safety/overvoltage_monitor/smoke_test.pyOr run all of them at once with tools/run_all_smoke_tests.py, which
finds every smoke_test.py in the repo so this list doesn't have to be
kept in sync by hand:
# from the repo root
python tools/run_all_smoke_tests.pyExits non-zero on any failed check.
tools/resolution_budget.py is a separate arithmetic check (no hardware or
ngspice): it reproduces the Pico-ADC / force-readout / plate-capacitance
numbers behind the "Bench-scale resolution budget" section of
docs/spacetime_circuits_dependency.md.
Each of these has been physically assembled and confirmed against its
main.py/smoke_test.py pass criteria on real hardware. Not committed
to a breadboard permanently — once a circuit's bench check passes and
nothing else currently under construction needs its wiring in place, its
parts go back to inventory; the netlist/breadboard.md/smoke_test.py stay
as the record for rebuilding it later, along with a breadboard.jpg
photo of the as-built jig where one was taken (see each circuit's own
README.md § Files).
| Folder | Circuit | Tier | Bench-tested |
|---|---|---|---|
power_supplies/psu_pico_rail/ |
Pico's own onboard 3.3V rail, ~100mA budget | interim bootstrap PSU | 2026-08 |
signal_conditioning/voltage_reference_lm358/ |
LM358 unity-gain buffer holds a resistor-divider reference steady under load | tier1 REF |
2026-08-27 — loaded reading within 0.23% of unloaded (±2% tolerance) |
measurement_tools/cd4066_switch_tester/ |
Pico-driven bring-up jig for one CD4066B analog switch — confirms it passes/blocks before trusting it in a later design | component validation (ahead of tier9 MUX) |
2026-08-28 — switch 1 (I/O A pin 1 / I/O B pin 2 / control pin 13) PASS on all 10 CD4066BCN units; switches 2–4 per chip not yet individually tested |
measurement_tools/fuse_test_voltmeter/ |
Pico ADC probe across a battery→fuse→resistor loop; arm switch (GP15) gates trip/reset detection so battery connect/disconnect isn't misread as a trip | bootstrap / concurrent measurement tool | 2026-08-28 — bench wiring has since diverged and trip detection is currently non-functional (no longer a blocker — polyfuses are now sorted via ammeter_10ohm/ammeter_1ohm below instead); see this circuit's own README § Current bench status for the full detail |
measurement_tools/ammeter_10ohm/ |
Pico reads current (not just voltage) through a polyfuse under test, via a 10Ω shunt + slide-switch shorting jumper | polyfuse validation (bootstrap tier) | 2026-08-30 — all 20 RXEF005 (50mA) polyfuses PASS (trip + reset confirmed per unit) |
measurement_tools/ammeter_1ohm/ |
Same approach as ammeter_10ohm scaled for 500mA: ~1Ω jumper-chain shunt (see resistance_measurement/) + 1N5817 reverse-polarity diode on the high side |
polyfuse validation (psu_low tier) |
2026-08-30 — all 20 RXEF050 (500mA) polyfuses PASS (trip + reset confirmed per unit) |
measurement_tools/resistance_measurement/ |
Voltage-divider jig (known 10Ω reference vs. unknown leg) for measuring a low-value resistance or checking continuity between two nodes | supporting tool for ammeter_1ohm; reused for continuity/troubleshooting checks (e.g. psu_4xaa) |
2026-08-30 — jumper-wire chain measured at ~1.005Ω, stable across repeated readings |
measurement_tools/raw_voltage_probe/ |
Plain averaged-voltage reader at GP26 — no resistance math, no divider assumptions; the calling circuit's own README supplies the target | general-purpose probe, split out of psu_4xaa 2026-09-07 for reuse |
2026-09-11 — confirmed both the ~0V (divider unpowered) and non-zero (~1.9V, psu_4xaa's divider) target readings against real hardware |
power_supplies/psu_ultralow_v1/ |
Single AA + 50 mA polyfuse | psu_ultralow (bootstrap) |
2026-08-30 — component-level validation complete: RXEF005 polyfuse PASS via ammeter_10ohm/ (all 20 units), AA battery holder ready per docs/inventory.md. The assembled PSU itself has not been separately re-probed as its own demo build (see fuse_test_voltmeter/README.md's test-vs-demo distinction) |
power_supplies/psu_4xaa/ |
4×AA in series + 1N5817 Schottky + 500 mA polyfuse | psu_system (top of the plain-AA-series progression) |
2026-09-11 — GP26 read ~1.9V through the output's 10 kΩ/5.1 kΩ divider, matching the ~0.338 ratio's prediction. An earlier ~0.14V fault on a different breadboard was never pinned to one component — rebuilding the same circuit on a second breadboard fixed it immediately (see README.md § Troubleshooting) |
oscillators/ne555_astable/ |
NE555 astable square-wave oscillator, 3296 trimpot timing | tier1 OSC, first per-unit NE555 batch validation |
2026-09-13 — oscillation confirmed (113/109 zero-crossings across two readings, ~1.5kHz, inside the expected 649Hz–2.9kHz trim range) via measurement_tools/oscillation_probe/. Output divider fixed: root cause was a mis-picked 220Ω resistor standing in for one of the two intended 10kΩ legs; swapped for a verified 10kΩ, GP26 now reads a real ~2.2V half-swing instead of pinning at 3.300V — see README.md § Validation |
measurement_tools/oscillation_probe/ |
Burst-sampled GP26 reader that reports min/max/swing and a zero-crossing count — confirms genuine toggling where raw_voltage_probe's averaging can't |
general-purpose probe, built 2026-09-12 for ne555_astable's bring-up |
2026-09-12 — used live against the ne555_astable bench build (see that row above) |
signal_conditioning/electric_field_probe/ |
Bare-electrode electrostatic sensor: 1MΩ/1MΩ bias divider to VCC/2, TL082 unity-gain follower | tier5 EPFIELD — spacetime-research sensor node, see docs/spacetime_circuits_dependency.md |
2026-09-15 — TL082 follower confirmed live (rest ~1.693–1.701V vs. simulated 1.650V, a small stable offset, not railed — resolves the earlier "hasn't been confirmed below spec'd supply" caveat). A piezo-igniter spark and a triboelectric (rubbed tape) test charge both produced no deflection beyond that same offset — consistent with the design's own predicted sensitivity ceiling from the 1MΩ (not GΩ) bias divider, not a wiring fault; see that circuit's own README § Bench findings for the diagnosis and concrete next steps |
power_supplies/psu_low_v2/ |
2×AA + Schottky + 500 mA polyfuse | psu_low tier |
2026-09-17 — GP26 read 1.007V average (20 readings) through the output's 10 kΩ/5.1 kΩ divider, matching the ~1.0V correct-orientation target. Root cause of an earlier no-reading gap: the Schottky's cathode band paint had worn off and it was installed backward on a guess — flipped once this check caught it; see README.md § Validation |
signal_conditioning/transimpedance_amplifier/ |
PT334-6C photodiode + LM358 current-to-voltage converter | tier2 TIA (fed from psu_low_v2) |
2026-09-17 — genuine light-dependent output confirmed: ~0.505–0.510V under ambient room light, ~0.72–0.78V under a phone flashlight (higher held close to the photodiode). Superseded a 2026-09-16 flat, light-independent ~0.38V reading that was traced to the psu_low_v2 rail above, not this circuit's own wiring — see README.md § Validation |
signal_conditioning/phase_detector/ |
SN74HC86N XOR gate compares ne555_astable's output tap against an independent Pico PWM reference, RC-lowpassed |
tier4 PHASED, feeds tier6 LOCKIN (undesigned) |
2026-09-19 — filtered output confirmed moving (0.871–1.546V over a ~3.5s window, not pinned at one extreme) as the two non-phase-locked oscillators drift, the real pass criterion per this circuit's own README § Validation. Required re-assembling ne555_astable first (broken back down to inventory since its own 2026-09-13 validation) |
safety/thermal_monitor/ |
MF52AT NTC divider (centers at VCC/2 at 25°C) + GPIO-driven alarm LED | safety THERM ("Thermal Monitoring with Alarm Threshold") |
2026-09-21 — ambient baseline stable at 1.708–1.713V / 10723–10790Ω / 23.3–23.5°C (close to the simulated VCC/2 midpoint, matching room temp being a couple degrees under the MF52AT's 25°C reference point); a sustained finger pinch drove a monotonic, physically-consistent response — resistance fell 10362Ω→8106Ω and reported temperature rose 24.2°C→29.8°C. Alarm LED correctly stayed off throughout (ALARM_THRESHOLD_C=40.0, never reached) — a true alarm trip hasn't been bench-tested yet. One transient outlier mid-run (3.253V/698639Ω/−47.4°C, one sample, self-corrected next reading) attributed to a momentary contact disturbance from handling the thermistor rather than a wiring fault — see kb/bench_photo_diagnostics_notes.md's matching 2026-09-21 entry |
measurement_tools/capacitance_bridge/ |
RC charge-time capacitance meter (known Rref=100kΩ vs. unknown Cx, timed against a 63.2%-of-Vin threshold) |
tier3 CAPBRIDGE |
2026-09-22 — a 47µF (25V) Cx from the electrolytic kit read 48.87µF/47.75µF/47.64µF across three consecutive runs, all within the kit's own ±20% tolerance of the 47µF nominal. A first attempt the same day (33µF Cx) read ~0.00–0.01µF on every run — traced to Rref's far lead resting on the breadboard's center divider ridge rather than seated in the junction hole, leaving the ADC node floating; reseating the lead fixed it. See kb/bench_photo_diagnostics_notes.md's matching entry |
measurement_tools/logic_analyzer_check/ |
Pico PWM square wave (GP15, 1kHz/25%) captured by the CY7C68013A board through sigrok-cli, frequency and duty checked on the host |
SCOPELA first capture (not a circuit; no netlist) |
2026-10-02 — 999.9Hz / 25.0% over 24 periods at 1MHz and at 4MHz; --find-channel reported D0 alone, so pad PB0 → D0. Under WSL it needs usbipd bind + attach --auto-attach on the firmware-loaded device (see its breadboard.md) |
Build order runs top to bottom: the voltmeter has to exist — and its own fuse-free sanity check has to pass — before it's trustworthy for sorting good polyfuses from bad, and a polyfuse has to be sorted good before it belongs in a PSU. See measurement_tools/fuse_test_voltmeter/README.md for the voltmeter self-check → bench-test-the-fuse-batch → demo-in-a-PSU sequence this drives.
| Folder | Circuit | Tier |
|---|---|---|
power_supplies/psu_3xaa/ |
3×AA + Schottky + 500 mA polyfuse | psu_system (between psu_low and psu_4xaa) |
power_supplies/psu_medlow_usbc/ |
5V USB-C + 500 mA polyfuse + bypass cap | psu_medlow — shelved 2026-09-23: not being built; psu_medlow_lm317 is the path forward. Kept as the record of the passive-breakout approach (see its README § Status) |
power_supplies/psu_medlow_lm317/ |
SFE Breadboard Power Supply Kit — LM317 adjustable, 3.3V/5V-selectable | psu_medlow (the adopted implementation; kit decided 2026-09-23, ordering from RobotShop; not yet built — see docs/TODO-arcticoder.md) |
signal_conditioning/charge_amplifier/ |
12mm piezo disc + TL082 inverting charge amp (Cf/Rf_bias feedback), VCC/2-biased for bipolar swing |
tier5 CHGAMP — a direct spacetime-research sensor node |
protection/active_current_limiter/ |
IRLZ44N + 0.1Ω sense resistor + LM358 comparator, hard-trip at 2A | general-purpose ACTIVELIM, protects psu_medhigh/psu_high (both backlog) |
signal_conditioning/accelerometer_interface/ |
GY-521 (MPU-6050) on I2C0 — bus-timing/supply simulation plus a bring-up script (ID, gravity, noise, vibration RMS) | tier5 ACCELIF (designed 2026-09-23); the measurement side of VIBISO |
measurement_tools/inductance_bridge/ |
PWM-driven parallel LC resonance sweep: unknown inductor vs. a known 10nF, Schottky peak detector, Pico ADC | tier3 INDBRIDGE (designed 2026-09-23); targets the 1µH–1mH color-ring assortment |
oscillators/vibration_driver/ |
S8050 low-side switch + 1N5817 flyback driving a 3V coin vibration motor from one Pico PWM pin (GP16) | tier1 SIMPGEN actuator stage and RIPPLETANK's dipper driver (designed 2026-10-01, revised 2026-10-02 for the ordered motor's 120mA stall current; motors on hand) |
signal_conditioning/adc_ads1115/ |
ADS1115 16-bit ADC on I2C0, with a 10kΩ/100nF/clamp-diode input network, checked against the Pico's own ADC on a shared divider | tier9 ADCDRV (designed 2026-10-01; one module on hand) |
signal_conditioning/lockin_amplifier/ |
Single-phase lock-in: AC-coupled LM358 gain stage, two CD4066B switches gated by complementary Pico-generated clocks, two RC averagers; test signal, anti-phase, 45°/90° and an asynchronous interferer all generated by the Pico | tier6 LOCKIN and tier4 DEMOD (designed 2026-10-02; wired 2026-10-05, demodulator behaves but gain is 4–5× the design value, Rbias found to be a 10kΩ on 2026-10-17, fix and a second fault in the B path pending — see its README) |
signal_conditioning/optical_shadow_readout/ |
Modulated LED + PT334-6C + TIA read through the lock-in's demodulator: how much light gets past a flag, with ambient light and lamp flicker rejected | tier5 FORCEBAL's optical readout (designed 2026-10-02; every part on hand; builds on lockin_amplifier) |
signal_conditioning/hall_amplifier/ |
SS49E/49E linear Hall sensor + LM358 difference amplifier with a trimpot null, 9.2mV per gauss about 0.94V | tier5 HALLAMP (designed 2026-10-02; sensors on hand) |
measurement_tools/frequency_counter/ |
Pico PWM-slice hardware edge counter, auto-ranged by a software gate; digital path (10kΩ + 1N5817 clamps) and an LM358 Schmitt path for sensor outputs | tier2 FREQC and bootstrap SIMPLECNT (designed 2026-10-02; every part on hand) |
measurement_tools/signal_generator_r2r/ |
Software DDS: PIO + two chained DMA channels play a sine table to an 8-bit R-2R ladder (1kΩ/2kΩ) on GP0..GP7, LM358P buffer; the Pico calibrates the ladder against its own ADC | TESTSIG (designed 2026-10-19; PIO/DMA half verified on a Pico, ladder not yet built; every part on hand) |
safety/overvoltage_monitor/ |
TL431A reference + LM358 comparator with hysteresis, trimpot trip point 1.5–8.8V, LED and a TRIP line for the Pico |
safety OVERVOLT (designed 2026-10-02; every part on hand; first use of the TL431A batch) |
Each of these (except psu_medlow_lm317, a kit with no netlist |
||
| of its own — see its own README) has a SPICE netlist, a generated | ||
schematic, a breadboard wiring guide, and a smoke_test.py (all but |
||
active_current_limiter also have a main.py, same reasoning as the |
||
PSU rows above having none). inductance_bridge's and |
||
accelerometer_interface's main.py files were exercised against |
||
host-side mocks only, not the Pico, as are the main.py files of the |
||
2026-10-01/02 designs (vibration_driver, adc_ads1115, lockin_amplifier, |
||
optical_shadow_readout, hall_amplifier, frequency_counter, |
||
overvoltage_monitor); the 2026-10-02 ones were also compiled under |
||
| MicroPython on the Pico, and the PWM register programming the lock-in family | ||
| uses was checked on the Pico against the logic analyzer. None of these have | ||
been physically assembled with real components yet (psu_low_v2, |
||
transimpedance_amplifier, and phase_detector were exceptions as of |
||
| 2026-09-16/2026-09-19, and all three moved to the bench-tested table | ||
| above once their validation checks passed — see their rows there and | ||
docs/TODO-arcticoder.md). |
||
| For the PSU rows, the polyfuses they depend on | ||
| are no longer the blocker — both batches passed validation via | ||
ammeter_10ohm/ammeter_1ohm above — so what remains is just the |
||
physical build; charge_amplifier runs off |
||
psu_pico_rail and has no battery-PSU dependency. Everything else in |
||
docs/general_purpose_circuit_dependency.md / |
||
docs/spacetime_circuits_dependency.md (most safety monitoring, most of |
||
| tiers 1–9) hasn't been worked out to netlist stage at all — folders for | ||
those will show up here as they get one. docs/TODO-arcticoder.md's |
||
| "Ready to build now" section tracks the physical-assembly status of | ||
| every row above. |
measurement_tools/fuse_test_voltmeter/,cd4066_switch_tester/,measurement_tools/capacitance_bridge/,measurement_tools/inductance_bridge/,signal_conditioning/accelerometer_interface/,signal_conditioning/voltage_reference_lm358/, andsignal_conditioning/transimpedance_amplifier/are the circuits here with Pico firmware (main.py) checked in. For more capable Pico ADC work (filtering, calibration curves, noise characterization), see the siblingpico/repo'smeasurement_tools/gpio_analog_sensing/— that repo isn't limited to one project, so general-purpose Pico infrastructure lives there rather than being duplicated here.- Getting the physical Pico talking to this PC (WSL +
usbipddevice attach, MicroPython firmware, installing/usingmpremote) is documented once in the siblingpico/repo rather than duplicated here — see pico/README.md § Running on real hardware. Needed any time you run one of this repo'smain.pyscripts against real hardware instead of just simulating. - See
docs/orders.mdfor what's actually been ordered/received from AliExpress,docs/parts_reference.mdfor pinouts/specs on those parts, anddocs/inventory.mdfor the master parts/quantities list — shared with the siblingpico/repo, which keeps a one-line pointer back to this file atpico/docs/inventory.mdrather than its own copy (seedocs/kb/repo_docs_conventions.md).
The torsion-balance study of spurious forces (printable balance, noise model, JLCPCB-assembled electronics) is in its own repo, spurious-force-balance; its prototype check uses this repo's lock-in amplifier and optical shadow readout.
measurement_tools/
fuse_test_voltmeter/ Pico ADC voltmeter, validates polyfuses via USB (built & bench-tested; trip/reset short test still pending)
fuse_test_voltmeter.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
cd4066_switch_tester/ CD4066B analog-switch bring-up jig (built & bench-tested)
cd4066_switch_tester.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
ammeter_10ohm/ 10Ω-shunt current-based polyfuse tester (built & bench-tested)
main.py
breadboard.jpg
README.md
ammeter_1ohm/ ~1Ω-shunt version for 500mA polyfuses (built & bench-tested)
main.py
breadboard.jpg
README.md
resistance_measurement/ voltage-divider jig for measuring an unknown low resistance (built & bench-tested)
main.py
breadboard.jpg
README.md
raw_voltage_probe/ plain averaged-voltage reader at GP26, no divider math (built & bench-tested; reused by psu_4xaa)
main.py
README.md
oscillation_probe/ burst-sampled GP26 reader, confirms genuine toggling vs. a stuck DC level (built & bench-tested; built for ne555_astable)
main.py
README.md
capacitance_bridge/ RC charge-time capacitance meter, targets the 1uF-470uF electrolytic kit (built & bench-tested 2026-09-22)
capacitance_bridge.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
logic_analyzer_check/ Pico 1kHz/25% PWM on GP15 captured by the CY7C68013A board via sigrok-cli, host script checks frequency/duty (SCOPELA first capture, designed 2026-10-01; the first attempt hit a WSL usbipd re-attach failure, not yet captured)
breadboard.md
main.py
check_capture.py
smoke_test.py
README.md
inductance_bridge/ PWM-driven parallel-LC resonance sweep for the 1uH-1mH color-ring inductor assortment (tier3 INDBRIDGE, designed 2026-09-23, not built)
inductance_bridge.spice
schematic.png (generated, gitignored)
breadboard.md
main.py
smoke_test.py
README.md
power_supplies/
psu_pico_rail/ Pico onboard 3.3V rail, ~100mA (interim, built & bench-tested)
psu_pico_rail.spice
schematic.png (generated, gitignored)
breadboard.md
smoke_test.py
README.md
psu_ultralow_v1/ single AA + 50 mA polyfuse (built & bench-tested — component-level)
psu_ultralow_v1.spice
schematic.png (generated, gitignored)
breadboard.md
smoke_test.py
README.md
psu_low_v2/ 2xAA + Schottky + 500 mA polyfuse (built & bench-tested 2026-09-17)
psu_low_v2.spice
schematic.png (generated, gitignored)
breadboard.md
smoke_test.py
README.md
psu_3xaa/ 3xAA + Schottky + 500 mA polyfuse (designed, not built)
psu_3xaa.spice
schematic.png (generated, gitignored)
breadboard.md
smoke_test.py
README.md
psu_4xaa/ 4xAA + Schottky + 500 mA polyfuse (built & bench-tested)
psu_4xaa.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
validation_breadboard.jpg
smoke_test.py
README.md
psu_medlow_usbc/ 5V USB-C + 500 mA polyfuse + bypass cap (shelved 2026-09-23, not being built)
psu_medlow_usbc.spice
schematic.png (generated, gitignored)
breadboard.md
smoke_test.py
README.md
psu_medlow_lm317/ SFE breadboard PSU kit, LM317 3.3V/5V-selectable (to be ordered from RobotShop, not built)
breadboard.md
README.md
signal_conditioning/
adc_ads1115/ ADS1115 16-bit ADC on I2C0 with a protected 10k/100nF input, checked against the Pico ADC (tier9 ADCDRV, designed 2026-10-01, module not on hand)
adc_ads1115.spice
breadboard.md
main.py
smoke_test.py
README.md
voltage_reference_lm358/ LM358 buffered voltage reference (built & bench-tested)
voltage_reference_lm358.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
transimpedance_amplifier/ PT334-6C photodiode + LM358 current-to-voltage converter (built & bench-tested 2026-09-17, real light response confirmed)
transimpedance_amplifier.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
electric_field_probe/ bare-electrode electrostatic sensor, TL082 follower (tier5 EPFIELD, built & bench-tested 2026-09-15)
electric_field_probe.spice
schematic.png (generated, gitignored)
breadboard.md
main.py
smoke_test.py
README.md
charge_amplifier/ 12mm piezo disc + TL082 inverting charge amp (tier5 CHGAMP, designed, not built)
charge_amplifier.spice
schematic.png (generated, gitignored)
breadboard.md
main.py
smoke_test.py
README.md
accelerometer_interface/ GY-521 (MPU-6050) I2C interface + bring-up script (tier5 ACCELIF, designed 2026-09-23, not built)
accelerometer_interface.spice
schematic.png (generated, gitignored)
breadboard.md
main.py
smoke_test.py
README.md
phase_detector/ SN74HC86N XOR phase detector + RC lowpass (tier4 PHASED, built & bench-tested 2026-09-19)
phase_detector.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
safety/
thermal_monitor/ MF52AT NTC divider + GPIO alarm LED (safety THERM, built & bench-tested 2026-09-21)
thermal_monitor.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
main.py
smoke_test.py
README.md
protection/
active_current_limiter/ IRLZ44N + sense resistor + LM358 comparator (ACTIVELIM, designed, not built)
active_current_limiter.spice
schematic.png (generated, gitignored)
breadboard.md
smoke_test.py
README.md
oscillators/
ne555_astable/ NE555 astable oscillator, 3296 trimpot timing (built & bench-tested — oscillation confirmed, output divider fixed 2026-09-13)
ne555_astable.spice
schematic.png (generated, gitignored)
breadboard.md
breadboard.jpg
breadboard2.jpg
smoke_test.py
README.md
vibration_driver/ S8050 switch + 1N5817 flyback for a 3V coin vibration motor on GP16 (tier1 SIMPGEN actuator stage, designed 2026-10-01, motor not on hand)
vibration_driver.spice
breadboard.md
main.py
smoke_test.py
README.md
docs/
history.md design conversation log
general_purpose_circuit_dependency.md general-purpose tier graph (PSU, protection, tiers 1-4/6/9, scope/logic-analyzer tiers M0-M5)
spacetime_circuits_dependency.md spacetime-specific tier graph (tiers 5/7/8)
TODO-arcticoder.md human TODO: single active/blocked/backlog checklist for both graphs above, plus personal action items
TODO-agent.md Claude-facing TODO: file/folder-creation tasks (netlists, docs) queued for Claude, before a build gets a bench bullet in TODO-arcticoder.md
TODO-completed.md dated audit trail of TODO-arcticoder.md/TODO-agent.md items once done — moved here, not deleted
inventory.md master component inventory (moved from pico/docs/inventory.md 2026-09-07)
orders.md AliExpress order log (received / on order)
parts_reference.md pinouts & specs for ordered parts without a datasheet on file
manuals/ converted (markitdown) part manuals; source PDFs gitignored
kb/ process notes for future LLM sessions, not end-user docs
tools/
spice_to_schematic.py generate schematic.png from a .spice file
ngspice_runner.py shared ngspice-invocation/parsing helper for smoke_test.py scripts
run_all_smoke_tests.py finds and runs every smoke_test.py in the repo
- Code (MIT, LICENSE): the Python and MicroPython sources (
main.py,diagnose_*.py,smoke_test.py,tools/). - Hardware designs and their documentation (CERN-OHL-P v2, LICENSE-HARDWARE): SPICE netlists, schematics and breadboard guides, parts tables and BOMs, and the build and inventory documents.