Public evidence

electrical.timer_555

Machine-checked verification for calculation version 1.2.0 · tier internally_reviewed

Open calculator API Capability Download JSON CVP Manifest MCP Review policy

CVP: CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance · ideal NE555 timing calculation· Ideal NE555 timing formulas. VERIFIED covers this calculation model, not assembled-circuit performance. Device applicability (frequency, pulse width) is a datasheet warning layer; board accuracy depends on the part and R/C tolerances. · Protocol · Schema · Production report

Declared partition coverage: PASS · 3/3 declared partitions (astable, monostable, invalid-domain)
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

Verification

Legacy regression suite: 30/30 calculation tests · Production surface contract 8/8

Three distinct suites: educational examples on the calculator page, this legacy regression count (30/30 golden + boundary), and the CVP verification suite below. They are not the same number. Property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the CVP Manifest . SKIP (0/0) means that suite has no published vectors.

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

CVP verification suite

Protocol checks from the Evidence Manifest. Distinct from the legacy regression suite above. Verification revision 2026-09-09.claim-scope. Calculation version 1.2.0. CVP 1.0.0-proposed. 2/2 golden · 7/7 CVP boundary · 5/5 invalid · 20/20 property · 2/2 cross-interface · 8/8 CVP contract. digest 0682b927e112. Ideal NE555 astable/monostable timing vs independent O2 (same V8, ≤2 ULP). Not a claim of assembled-circuit frequency or pulse accuracy.

Golden (oracle-backed) 2 / 2
CVP boundary 7 / 7
Invalid input 5 / 5
Property 20 / 20
Cross-interface 2 / 2
CVP contract 8 / 8
Interfaces PASS · UI (SSR) / REST / MCP
Interface claim ui-ssr is query-result HTML, not a live browser session.
Verified scope ideal NE555 timing calculation
Assurance Engineering

contract page version PASS
contract capability version PASS
contract input schema version PASS
contract output schema version PASS
evidence version matches manifest PASS
schema valid input executes PASS
engine success output validates schema PASS
schema rejects incomplete input PASS

Fingerprint sha256:1a51575bf7b0ceba9f65415e320250f555e4e84e56bcee0c6e35e9c84dc080c5

Input schema sha256:28c7a7495fb90986ab08fc38e0861f68022f58ce939c9a2f4d7325767a94301b · Output schema sha256:fbf0aeb7cd3b62a5f0749610a7a4c6a0bec3152dee5773f0e965d687b4a4d633 · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: timer-555
Engine: timer-555
Engine build: 2026-09-10
Evidence core: 2026-09-09T14:46:37.636Z
Rendered: 2026-09-16T22:03:43.731Z
Last reviewed: 2026-08-13

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

Limitations

Classic NE555 ideal timing — astable uses ln(2) canonical model; TI 0.693/1.44 are rounded aliases
Device families differ in timing accuracy, leakage, output/discharge characteristics and usable frequency range; verify the selected device datasheet
Standard astable wiring always yields duty > 50%; diode-across-R2 <50% trick is not modeled
f > 100 kHz → NE555_HIGH_FREQUENCY warning (NE555 distortion guidance)
Monostable pulse_width < ~10 µs → MONOSTABLE_SHORT_PULSE warning
mode-discriminated oneOf: astable requires R1,R2,C; monostable requires R,C
Frozen at calculation_version 1.2.0 for forward timing — Designer / E-series / tolerance are separate surfaces

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

NE555 datasheet timing equations (TI xx555 Precision Timers) — Astable / monostable
Supports: tH/tL ≈ 0.693·RC (rounded ln(2)); f≈1.44/((R1+2R2)C) rounded 1/ln(2); tw=1.1RC; ≤100 kHz guidance; ~10 µs monostable floor
Horowitz & Hill — The Art of Electronics — 555 timer circuits
Supports: Astable / monostable RC timing identities

Legacy published checks

Golden and boundary cases from the legacy Evidence JSON. CVP property, metamorphic, round-trip, O3, and interface statuses/checks are recorded in the Manifest — including SKIP when a suite has no vectors.

ID	Kind	Status	Detail
`astable`	golden	pass	Expected f_Hz=68.69976385185541 · Actual mode=astable · f_Hz=68.69976385185541 · period_s=0.01455609079175885 · high_time_s=0.007624618986159398 · low_time_s=0.006931471805599452 · duty=0.5238095238095238 · duty_pct=52.38095238095239
`mono`	golden	pass	Expected pulse_width_s=0.011 · Actual mode=monostable · pulse_width_s=0.011 · pulse_width_ms=11
`bad-R`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`bad-mode`	boundary	pass	Expected INVALID_MODE · Actual INVALID_MODE
`missing-mode`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`hf-warn`	golden	pass	warning NE555_HIGH_FREQUENCY
`boundary-555-astable`	boundary	pass	Expected f_Hz=68.69976385185541 · period_s=0.01455609079175885 · duty=0.5238095238095238 · Actual mode=astable · f_Hz=68.69976385185541 · period_s=0.01455609079175885 · high_time_s=0.007624618986159398 · low_time_s=0.006931471805599452 · duty=0.5238095238095238 · duty_pct=52.38095238095239
`boundary-555-astable-missing-R2`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-555-mono-missing-R`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-555-short-pulse`	boundary	pass	warning MONOSTABLE_SHORT_PULSE
`property-555-f`	property	pass	f
`property-555-period`	property	pass	T=1/f
`property-555-th-tl`	property	pass	tH+tL=T
`property-555-ln2`	property	pass	tH/tL=ln(2)·RC
`property-555-duty`	property	pass	duty>50%
`property-555-duty-pct`	property	pass	duty_pct
`property-555-C-scale`	property	pass	2×C → ½f
`property-555-R-scale`	property	pass	2×R → ½f
`property-555-R-permutation`	property	pass	R1/R2 not interchangeable
`property-555-duty-gt50`	property	pass	duty>50% samples
`property-555-low-f`	property	pass	large RC → low f
`property-555-hf-warn`	property	pass	f>100kHz still returns a finite result with NE555_HIGH_FREQUENCY warning (not invalid input)
`property-mono-T`	property	pass	tw
`property-mono-ms`	property	pass	ms=s×1000
`property-mono-R-scale`	property	pass	2×R → 2×tw
`property-mono-C-scale`	property	pass	2×C → 2×tw
`property-mono-short-warn`	property	pass	tw<10µs still returns a finite result with MONOSTABLE_SHORT_PULSE warning (not invalid input)
`property-schema-astable`	property	pass	astable fields
`property-schema-mono`	property	pass	monostable fields
`property-555-no-warn-nominal`	property	pass	nominal no warning