Basic and power tool review

Reviewed the actual calculator fragments, equations, displayed claims and loading behavior. Restored tools are analytic arithmetic aids, not measurement-correlated hardware models. All are self-contained inline scripts; no retired shared engine or special initializer is required. Each script runs inside a local closure and exports only its UI handlers, so repeat navigation cannot redeclare lexical state or replace another tool’s generic formatting helper.

Fragment Decision and model scope Corrections and evidence
resistor-divider Restore: loaded DC resistor divider Replaced the previous shared-script-dependent UI and package-size guesses with an explicit load resistance. Checks 12 V / 1 kohm / 1 kohm gives 6 V open circuit, 4 V with a 1 kohm load; resistor loss checks and invalid values.
e-series-finder Restore: nearest preferred nominal value Uses actual E12/E24/E96 tables, not generated geometric rounding; searches adjacent decades. 4850 selects E24 4700 and E96 4870; 99 selects E12 100. Series membership does not guarantee a component tolerance.
smd-resistor Restore: common nominal code decoder Rejected malformed decimal strings, fixed R047 decoding, restricted ambiguous multiplier aliases, removed claims that nominal codes establish tolerance. Checks 103, 1002, R047, 4R7, 01C and 000 plus malformed input.
led-resistor Restore: constant-Vf DC series resistor estimate Requires positive finite current/voltages and integer LED count. E12 rounds upward rather than choosing a lower value that exceeds target nominal current. The 2× example power rating is explicitly arithmetic, not a thermal/safety result. Checks 5 V, 2 V, 20 mA gives 150 ohm and 60 mW, upward rounding and invalid current.
555-timer-calc Restore: ideal astable/monostable timing Uses ln(2) charge/discharge and ln(3) monostable equations consistently; frequency now equals reciprocal computed period. Invalid R/C clears results. Checks 1 kohm/1 kohm/1 uF gives 480.9 Hz, 66.7% duty; monostable 1.099 ms. Real IC/component tolerances remain outside scope.
current-sense-amp Restore: ideal shunt/amplifier/ADC scaling Three solve paths checked for 10 A, 50 mV, 3.3 V: 5 mohm, gain 66, 0.5 W, 2.44 mA per 12-bit code. Nonfinite/nonpositive inputs clear result fields. Added explicit output-headroom, common-mode, noise and tolerance exclusions.
battery-life-estimator Restore in narrower form: usable-capacity/mean-current estimate Removed chemistry presets and an unsupported annual aging curve. User supplies usable capacity and active/sleep current with duty. 2000 mAh, 100 mA, 10% active and zero sleep gives 200 h. No safety or aging prediction.
battery-pack-s-p-config Restore in narrower form: series/parallel arithmetic Removed generic chemistry current/resistance presets, fixed cell-mass assumption, automatic sizing policy and “fully safe”/“thermally balanced” verdicts. User supplies identical-cell nominal data. 4S2P, 3.6 V/3 Ah cells gives 14.4 V/6 Ah/86.4 Wh; 5 A and 20 mohm/cell gives 1 W lumped resistive loss. No cell/BMS qualification.
grid-power-calc Restore: sinusoidal single-phase/balanced three-phase power Corrected displayed three-phase capacitance to each delta branch and its formula. Rejects invalid PF instead of silently clamping. 400 V line-to-line, 10 A, PF 0.8: 6.93 kVA, 5.54 kW, 4.16 kvar; unity correction at 50 Hz needs 27.6 uF per delta branch. No distortion-PF, harmonics or resonance analysis.
hydro-power-calc Restore: steady-flow power balance Explicit net head and supplied turbine/generator efficiencies, water density 1000 kg/m³, g 9.81 m/s². Rejects efficiencies outside (0, 100%]. 10 m, 1 m³/s, 80% turbine and 90% generator gives 70.63 kW. No turbine selection, annual yield or hydraulic-loss solver.
unit-converter Restore: stated SI factors and log references Blank/nonfinite input and temperature below absolute zero no longer produce plausible zero outputs. Nonpositive linear-to-log cases produce no result. Removed an unrelated impedance conversion explanation. Checks inch/mm, Wh/J, Celsius/Fahrenheit, dBm/W and dBmV/V. BTU and horsepower conventions are stated.
opamp-calc Keep out in its current form Actual code uses closed-loop signal gain rather than noise gain to infer bandwidth for every topology; transient plots multiply inputs by static gain and clip at an arbitrary 0.5 V rail margin. Several “real” inputs do not define a traceable amplifier model. A future separate ideal-gain calculator could be restored after removing the broader simulation claims.
smps-topology-ratio Keep out in its current form The UI offers isolated topologies that reach a generic buck-boost/SEPIC fallback. The flyback branch mixes target-duty transfer-ratio and triangular-current assumptions without selecting/qualifying CCM/DCM. Stress outputs apply undocumented 1.2×/1.3× multipliers and generic current/capacitor equations across modes. Needs topology-specific model contracts and reference comparisons.

Primary references

Verification

node --test tests/basic-tools.test.cjs executes the actual fragment scripts with a minimal DOM fixture: 12 tests cover representative numeric outputs, negative or zero/domain-invalid inputs, successive solve paths and repeated mounting. Passing these checks establishes only the stated analytic behavior and script lifecycle; it is not hardware correlation or a browser visual check.