# DIAC

Canonical URL: https://eloragrid.ai/symbols/diac
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: DIAC
Drawing use: Schematic
Reference families: IEC, Manufacturer

A DIAC is a bidirectional triggering semiconductor device used in a documented control circuit.

## What it represents

A DIAC is a bidirectional triggering semiconductor device used in a documented control circuit. Its terminals and breakover characteristics are defined by the selected component.

## How to read it

- Follow the trigger circuit rather than treating the device as a controlled switch with a separate gate.
- The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation.

## Information to show or reference

- Identify connected terminals
- Reference breakover rating
- Show associated trigger network

## Important distinction

A DIAC does not have the same controlled gate terminal as a TRIAC.

## Facts

- Drawing role: Semiconductor function
- Representation scope: Functional concept; not an official standard graphic or a product footprint
- Public vendor block reference: HDI1V3, VDI1V3 (Autodesk identifiers; not IEC symbol numbers)
- Identifier status: The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name.

## Public references

- [AutoCAD Electrical: Semiconductor components](https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-AC954072-7314-4682-88AF-38160D61E9A2.htm) — Autodesk. Public documentation of this equipment function or named vendor variant; the illustration is independently authored and is not the source graphic.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.