PD
Photodiode
A photodiode is a light-sensitive semiconductor device used in a documented sensing circuit.
Schematic
Symbols · PHOTO-NPN
NPN phototransistor
An NPN transistor whose collector-emitter conduction responds to incident light in the documented detector arrangement.
Schematic · PHOTO-NPN
What it represents
An NPN transistor whose collector-emitter conduction responds to incident light in the documented detector arrangement.
On a schematic, identify the collector/emitter connections and any accessible base terminal and trace the optical sensing and load circuit. Keep the component tag and signal/reference names consistent across the control drawing, terminal schedule and device documentation.
A phototransistor provides transistor action; a photodiode generates a different detector current response.
Terminal letters describe electrical roles, not package pin numbers. Check the selected public datasheet for the actual pin assignment, polarity and any internally connected terminals before completing the drawing.
How to read it
- Identify the collector/emitter connections and any accessible base terminal.
- Trace the optical sensing and load circuit.
Information to show or reference
- Label the collector/emitter connections and any accessible base terminal.
- Cross-reference the optical sensing and load circuit.
- Add the selected device or circuit documentation revision, power/reference connections and project signal convention.
A distinction that matters
A phototransistor provides transistor action; a photodiode generates a different detector current response.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
BPW77 silicon NPN phototransistor documentation
Public primary manufacturer documentation establishes the component function or circuit/topology relationship. Preview geometry and drafting explanations are independently authored.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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