# Circuit Diagram (回路図)

> Engineering's language of standardized symbols and orthogonal lines. Discarding physical placement to record only connection — a topology of drawing that preceded even the transit diagram.

- IndexStyle No.433 — https://indexstyle.org/styles/circuit-diagram
- Kind: Style · Family: Diagrammatic Expression · Era: 1890s–
- Mood: Technology, Trust, Calm
- Color cues: #e9e6dd / #67635d / #171615 (cues taken from reference works, not a fixed palette)

## Defining characteristics

- Standardized component symbols
- Orthogonal wiring
- Junction dots
- Abstraction from physical layout

## Best used for

- Comparing primary sources and canonical works
- Extracting principles that transfer to other media

## Research method

This entry records a historical style; derive the treatment from its sources rather than a fixed recipe:

- Observe the letters, signs and scale of reference works
- Extract the one structure that governs gaze and information
- Verify the materials and behaviors specific to era, region and process

## What to avoid

Don't reduce it to surface signs. Verify the context of era, region, technology and makers.

## Application checklist

Before calling a piece an application of this style, check it against the defining characteristics:

- [ ] Standardized component symbols
- [ ] Orthogonal wiring
- [ ] Junction dots
- [ ] Abstraction from physical layout
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **Blueprint (ブループリント)** — Shows the lines of thinking rather than the finished thing — structure and possibility. → https://indexstyle.org/styles/blueprint
- **Flowchart (フローチャート)** — The process drawing the Gilbreths invented for work analysis. The grammar of shapes — diamond for decision, rectangle for process — passed through programming to become the common language of thinking in steps. → https://indexstyle.org/styles/flowchart

## Further study

- the IEC 60617 symbols
- learning to read schematics
- the division of labor with PCB layout

## Reference works

- ラジオ受信機の回路図 1920 — https://commons.wikimedia.org/wiki/File:Heterodyne%20radio%20receiver%20circuit%201920.png
- アマチュア無線の回路図 — https://commons.wikimedia.org/wiki/File:Schematic%20diagram%20on%20the%20general%20class%20amateur%20radio%20test.JPG

## Source of record

- The Institution of Engineering and Technology — https://www.theiet.org/

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/circuit-diagram
- Image-generation prompt (legally clean): https://indexstyle.org/styles/circuit-diagram/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compose_styles; prompts: image-prompt, apply-style)

## 日本語

電気回路を規格化された記号と直交する線で描く工学の言語。物理的配置を捨てて接続関係だけを写す抽象化は、路線図にも先行する「トポロジーの図法」だった。

特徴: 規格化された素子記号／直交する配線／接続点のドット／物理配置からの抽象
注意: 表面的な記号へ還元せず、時代・地域・技術・制作主体の文脈を確認する。