Accuracy and Sources

Accuracy and Sources

How much should you trust what the tool tells you? This page explains how the data was checked and where you need to be careful.

How was it checked?

Every table and value in the tool was audited against published sources: manufacturer datasheets, distributor references, and standards documents. Where a value could not be confirmed, it was reworded, flagged, or removed. The full record, with a link for each item, is in SOURCES.md.

The checks found and fixed real mistakes, for example a wrong capacitor voltage code, color-code tolerance entries that no source supported, and several ratings that vary between makers. Fixing those is the point of keeping a public record.

What is solid?

• Color codes and value tables: resistor colors, the E24 and E96 series (checked value by value against the published list), EIA-96 multipliers, capacitor tolerance letters, and EIA voltage codes.
• Standards-based codes: IEC 60127 fuse breaking capacity and speed codes, and the common SMD value codes.
• Datasheet-backed examples: the varistor ratings for the 14D471K and S14K275, and the 10.7 MHz filter dot colors.

What varies between manufacturers?

• Pinouts. Some TO-92 parts are wired one way at one maker and the opposite at another (the BC547, 2N3904, PN2222A, and S8050 are examples). The tool states which maker's order it shows.
• SMD marking codes. The same part can carry different codes from different makers, and makers often add a prefix or a date code.
• Ratings. Maximum current and voltage for the same part number can differ between makers (for example the AMS1117 regulator).

What is estimated?

• Tolerance read from an SMD marking. Most markings do not encode tolerance, so the tool gives the typical one for that style and says so.
• Varistor AC and DC ratings and clamping range. Calculated from standard ratios, matched against catalog parts.
• Thermistor resistance at a temperature. Uses the beta model.
• Crystal load capacitors. Assume about 4 pF of stray capacitance.

What could not be confirmed?

These are worded cautiously, flagged, or left out:

• The exact value of lowercase a in EIA-198 (2.6 in the DigiKey table, 2.5 in some others).
• The Murata resonator characters after the frequency field (tolerance, load capacitance, packaging).
• A few part pin numbers for the LM2596 and MCP1700 (the tool prompts you to check the datasheet).
• Varistor tolerance letters other than K.

How should I use the results?

1. Treat the tool as a fast first answer and a way to learn the pattern.
2. For anything that matters (a design limit, a safety part, a mains circuit), confirm with the manufacturer datasheet for your exact part.
3. When in doubt, measure the part out of circuit with a meter.

Found a mistake?

Please open an issue and cite the datasheet or standard. Corrections with a source are the fastest to fix, and they get added to the public record.