Source: https://guthlabs.ai/docs/instruments/schmitt-trigger-threshold-calculator/implementation/

instrument implementation / implementation-contract

# Schmitt Trigger Threshold Calculator implementation

A source-bound implementation contract for Schmitt Trigger Threshold Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **implementation-contract**

## 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-with-binding-errata

**Evidence ID**: t5-189

**Effect**: Computation or source lookup only

## Input and validation requirements

The denominator can be forced to zero with R1+R2=0, producing an undefined threshold that must be rejected. In addition, the specification provides only one threshold formula and does not explicitly define how VTH_plus and VTH_minus, reference polarity, or signed hysteresis are derived.

## Required corrections

````
[
  {
    "vector": 2,
    "field": "VTH_plus/minus/hysteresis",
    "wrong": "±9.4737 / 18.947",
    "correct": "±9.8947 / 19.789",
    "cause": "outputs contradict her own working which computes (and self-corrects to) 9.8947"
  }
]
````

## Inspectable interface fixture

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

````
{
  "inputs": {
    "Vsat": 5,
    "R1": 10000,
    "R2": 20000,
    "reference_config": "zero reference; symmetric rails; R1 and R2 in ohms"
  },
  "expected_outputs": {
    "VTH_plus": 1.6666666667,
    "VTH_minus": -1.6666666667,
    "hysteresis": 3.3333333333
  },
  "working": "R1+R2=10000+20000=30000 ohms. VTH magnitude=5×10000/30000=50000/30000=1.6666666667 V. VTH+=+1.6666666667 V. VTH−=−1.6666666667 V. Hysteresis=VTH+−VTH−=1.6666666667−(−1.6666666667)=3.3333333333 V."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/schmitt-trigger-threshold-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/schmitt-trigger-threshold-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/schmitt-trigger-threshold-calculator/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `tranche errata record`