{"schemaVersion":1,"slug":"iec-non-retriggerable-monostable","name":"IEC non-retriggerable monostable","kind":"symbol","abbreviation":"1⊓","aliases":["one-shot","non-retriggerable monoflop","single-pulse element"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEC","Manufacturer"],"summary":"IEC monostable marked with 1 and a single pulse: a trigger during the output pulse is ignored.","description":["The non-retriggerable monostable produces one output pulse of fixed duration when triggered. Further triggers during that pulse have no effect. IEC drawings show the qualifier 1 with a single pulse shape inside the outline, and timing component connections are shown as non-logic inputs.","These elements are used to stretch short events into pulses long enough to be seen by slower logic, or to produce a fixed-width command. The external resistor and capacitor that set the pulse width should be drawn next to the element and the nominal width stated.","Pulse width tolerance depends on the timing components and the device. The symbol shows the behaviour, not the accuracy."],"readingNotes":["Retriggers during the pulse are ignored.","Find the timing resistor and capacitor connections."],"drawingChecklist":["Show the single-pulse qualifier.","Draw the timing components and state the nominal width.","Mark trigger input edge sense."],"distinction":"The retriggerable monostable extends its pulse on each new trigger and is drawn without the 1.","facts":[{"label":"Retrigger behaviour","value":"Ignored during pulse"},{"label":"Example device","value":"Dual monostable multivibrators with Schmitt-trigger inputs"},{"label":"Artwork scope","value":"Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic"}],"references":[{"sourceId":"s28-ti-ieee91-logic-symbols","relevance":"Lists the nonretriggerable monostable general qualifier."},{"sourceId":"s28-ti-ls221","relevance":"Manufacturer monostable multivibrator documentation."}],"related":["iec-retriggerable-monostable","retriggerable-monostable","iec-astable-element"],"artwork":"s28-iec-non-retriggerable-monostable","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Rectangular element with the 1 and single-pulse qualifier","reference":"Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier."},"plainEnglish":{"title":"What does IEC non-retriggerable monostable mean?","introduction":"The non-retriggerable monostable produces one output pulse of fixed duration when triggered. Further triggers during that pulse have no effect. IEC drawings show the additional drawing mark 1 with a single pulse shape inside the outline, and timing component connections are shown as non-logic inputs.","example":"These elements are used to stretch short events into pulses long enough to be seen by slower logic, or to produce a fixed-width command. The external resistor and capacitor that set the pulse width should be drawn next to the element and the nominal width stated.","drawings":"Pulse width tolerance depends on the timing components and the device. The symbol shows the behaviour, not the accuracy.","terms":[{"name":"Normally open / normally closed","meaning":"The contact state in the normal condition defined for the drawing."},{"name":"Terminal","meaning":"An identified point where a conductor connects."},{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf"},{"label":"SN74LS221 dual monostable multivibrators with Schmitt-trigger inputs","url":"https://www.ti.com/lit/ds/symlink/sn74ls221.pdf"}],"detail":"IEC monostable marked with 1 and a single pulse: a trigger during the output pulse is ignored. The retriggerable monostable extends its pulse on each new trigger and is drawn without the 1.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-non-retriggerable-monostable","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-non-retriggerable-monostable.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"s28-ti-ieee91-logic-symbols","title":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf","type":"manufacturer","scope":"Public explanation of rectangular logic symbols, general qualifiers, input and output qualifiers, dependency notation, bistable elements and coders, consistent with IEC 617-12 work.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Lists the nonretriggerable monostable general qualifier."},{"id":"s28-ti-ls221","title":"SN74LS221 dual monostable multivibrators with Schmitt-trigger inputs","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ds/symlink/sn74ls221.pdf","type":"manufacturer","scope":"Device documentation for non-retriggerable monostable multivibrators.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Manufacturer monostable multivibrator documentation."}]}