Verified calculation capability

555 Timer Calculation Capability

Astable frequency/duty/timing and monostable pulse width for the classic 555 using ln(2)-canonical NE555 timing (TI 0.693/1.44 are documented rounded aliases). · Electrical

Capability ID electrical.timer_555 · version 1.2.0

Open calculator REST API MCP Evidence Evidence JSON CVP Manifest Review policy

Model

Astable high / low (canonical)

Astable high / low (canonical): tH = ln(2)·(R1+R2)·C · tL = ln(2)·R2·C
Astable period / frequency: T = tH+tL · f = 1/T
Astable duty: duty = (R1+R2)/(R1+2·R2)
Monostable pulse width: tw = 1.1·R·C
Datasheet rounded forms: 0.693 ≈ ln(2) · 1.44 ≈ 1/ln(2)

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`formula`	—	—	output
`api_version`	—	—	output
`api_contract_version`	—	—	output
`spec_version`	—	—	output
`page`	Canonical calculator page URL	—	output
`links`	—	—	output

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

Classic NE555 ideal timing thresholds (≈⅓ / ⅔ VCC)
Standard astable topology without duty-cycle diode
Astable timing uses ln(2); TI 0.693/1.44 are rounded aliases

Not supported

Full SPICE · CMOS-specific electrical models · Duty-cycle diode trick (<50%) · Automatic R/C E-series design (future Designer surface)

Example

One numerical check. The calculator page holds worked steps and FAQ.

R1=1k R2=10k C=1µF → ~68.70 Hz · duty 52.38%

Open this example in the calculator

Trust

CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance · ideal NE555 timing calculation. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.

CVP: CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance · ideal NE555 timing calculation· View Manifest · CVP overview · Specification
Verified scope: ideal NE555 timing calculation
Assurance: Engineering
Declared partition coverage: PASS · 3/3 declared partitions (astable, monostable, invalid-domain)
Calculation version: 1.2.0
Verification: 30/30 calculation tests · 3/3 legacy golden · 7/7 legacy boundary · 20/20 legacy property
Production surface contract: 8/8
Versions: Calculation 1.2.0 · CVP protocol 1.0.0-proposed · Evidence 2026-09-09.claim-scope
Verification revision: 2026-09-09.claim-scope · 20/20 property · digest 0682b927e112
Reference: O1 model · O2 expected_values · O2 numerical_behavior
Numerical scope: Ideal NE555 astable/monostable timing vs independent O2 (same V8, ≤2 ULP). Not a claim of assembled-circuit frequency or pulse accuracy.
Interfaces: PASS · UI (SSR) / REST / MCP
ui-ssr is query-result HTML, not a live browser session.
CVP suite: 2/2 golden · 7/7 CVP boundary · 5/5 invalid · 20/20 property · 2/2 cross-interface · 8/8 CVP contract
Supplemental domain review: Internal · Pass · electrical-engineer · CalculatorX electrical review · 2026-08-13
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.2.0 (workspace artifacts agree)
Review-policy tier: Internally reviewed — catalog token internally_reviewed; supplemental; not CVP status

This calculator CURRENT · Public schema 1.2.0 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 8/8.

Tool id: timer-555
Engine: timer-555
REST: POST /api/v1/calc/timer-555
MCP: execute_calculation with capability_id: "electrical.timer_555"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.2.0)
Versioned output schema: Immutable pin (1.2.0)

Operations

Declared calculation modes for this capability.

astable
monostable

References

Human-readable sources plus CVP reference evidence classes.

Sources

NE555 datasheet timing equations (TI xx555 Precision Timers) — Astable / monostable
Horowitz & Hill — The Art of Electronics — 555 timer circuits

Reference evidence classes: O1 model · O2 expected_values · O2 numerical_behavior

Try with an agent

Inspect this capability via same-origin MCP, then call execute_calculation.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"electrical.timer_555"}}}'

Inspect the trust tier and required assurance level before execution. Pin calculation_version (1.2.0) when reproducibility matters. Full protocol notes: MCP docs.