DETAILED SPECIFICATIONS
Diode Family / Application
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Input Parameters Specification
Band Coding StandardEIA/JEDEC (e.g. 1N4148), Pro Electron (European standard e.g. BAX13), or single-band general parameters.
First Band (Prefix/Material)Identifies either the semiconductor substrate material (e.g. Silicon or Germanium) or JEDEC standard digits.
Second Band (Function/Application)Represents specialized signal categories such as low-leakage, varactors, Zeners, or secondary digits.
Suffix / Calibration LettersOptional trailing color band indicating tolerance categories or gain levels.
Practical Operational Examples
Silicon General Zener (Blue Band)
A single blue band under standard classification identifies the component as a Zener Diode.
1N4148 General Switching (JEDEC)
Decodes via standard JEDEC 5-band sequence. Represents high-speed silicon planar switching structures.
Germanium Varactor (AAX series)
Pro Electron standard: Band 1 (Germanium) + Band 2 (Varactor category) followed by numeric serial series identifiers.
Schottky Signal Diode (Green Band)
Uses a single green band indicator. Identifies low forward-voltage metal-semiconductor Schottky junction barrier diodes.
Diagrams & Theory
Axial leaded glass-body diodes (such as DO-35 or DO-41 form-factor casings) are extremely compact, making it difficult to print alphanumeric labels on their rounded surface. Manufacturers use color-coded bands to indicate part numbers.
These bands are usually offset closer to the **Cathode terminal (negative end)**. To decode, orient the diode so the thickest or most concentrated grouping of color lines is on the left, then read from left to right towards the cathode.
Formulas & Mathematical Logic
JEDEC 5-Band: Indicated part is 1N + [Band 1 Digit][Band 2 Digit][Band 3 Digit][Band 4 Digit] + [Band 5 Suffix]
Pro Electron 4-Band: Part code is [Band 1 Material Letter][Band 2 Category Letter] + [Band 3 Digit][Band 4 Digit]
Step-by-Step Example
Example: Decoding a JEDEC 5-Band Diode (with Yellow, Red, Black, Yellow, and Brown Bands)
Step 1: Read prefix - JEDEC standard series always implies the "1N" structure.
Step 2: Read Band 1 (Yellow) = "4".
Step 3: Read Band 2 (Red) = "2".
Step 4: Read Band 3 (Black) = "0".
Step 5: Read Band 4 (Yellow) = "4".
Step 6: Read Band 5 (Brown) = "A" (Tolerance suffix). Decodes as "1N4204A".
How to Use This Calculator
Choose the target standard using the interactive Band Coding Standard picker on the panel.
Read the bands sequentially starting from the end furthest from the silver end caps.
Tap each band picker button to open the convenient iOS selection wheel.
The calculated values, standard categories, and substrate properties update in real-time.
Frequently Asked Questions
1. Which end of the diode is the cathode?
The cathode (negative terminal) is indicated by the color bands or terminal stripe. On leaded axial diodes, color bands are clustered closer to the cathode end.
2. What is the difference between a Zener diode and a standard diode?
Standard diodes conduct only in the forward direction. Zener diodes are designed to conduct reliably in the reverse direction once a specific 'breakdown voltage' is reached, making them useful for voltage regulation.
3. What does the '1N' prefix stand for?
The '1N' prefix is part of the JEDEC standard, where '1' represents the number of active semiconductor junctions (diodes have 1 junction, transistors typically have 2, marked '2N').
4. How do I identify a Schottky diode via color bands?
Under general single-band coding standards, a single green band printed on the diode represents a Schottky classification.