LED Series Resistor Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-186

Effect

Computation or source lookup only

Input and validation requirements

The calculator can encounter undefined output at If=0, can produce zero or negative resistance at and below the LED forward-voltage boundary, and can produce results differing by a factor of 1000 or more when current units are ambiguous. These cases require rejection, warning, or explicit unit handling.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "supply_V": 5,
    "LED_forward_voltage_V": 2,
    "series_count": 2,
    "target_current_A": 0.02
  },
  "expected_outputs": {
    "R_exact_ohm": 50,
    "P_exact_R_W": 0.02,
    "nearest_standard_value_E12_ohm": 47,
    "minimum_continuous_rating_before_margin_W": 0.02
  },
  "working": "Voltage across resistor = 5 − (2 × 2) = 5 − 4 = 1 V. R = 1 / 0.020 = 50 ohm. P = I²R = 0.020² × 50 = 0.0004 × 50 = 0.020 W. Nearest E12 values are 47 ohm and 56 ohm; |50−47|=3 and |56−50|=6, so nearest = 47 ohm."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json