C ADJ
Adjustable capacitor
An adjustable capacitor provides a documented variable capacitance.
SLD / Schematic
Symbols · VAR
Varactor diode
A reverse-biased diode whose junction capacitance is used as a voltage-controlled circuit element.
Schematic · VAR
What it represents
A reverse-biased diode whose junction capacitance is used as a voltage-controlled circuit element.
On a schematic, identify the tuning bias, cathode orientation and RF node and trace the tuned or phase-control circuit. Keep the component tag and signal/reference names consistent across the control drawing, terminal schedule and device documentation.
A varactor uses junction capacitance under reverse bias; it is not an adjustable mechanical capacitor.
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 tuning bias, cathode orientation and RF node.
- Trace the tuned or phase-control circuit.
Information to show or reference
- Label the tuning bias, cathode orientation and RF node.
- Cross-reference the tuned or phase-control circuit.
- Add the selected device or circuit documentation revision, power/reference connections and project signal convention.
A distinction that matters
A varactor uses junction capacitance under reverse bias; it is not an adjustable mechanical capacitor.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
BB181 variable-capacitance diode 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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