Vintage Band Reading
Bumble bee capacitors are molded paper or film style parts with colored stripes. Many appear in radios, amplifiers, test gear, and old guitar circuits. Their bands can look like resistor bands, yet the meaning is different. This calculator reads the classic six band arrangement used on many Sprague style parts. It turns the stripe order into capacitance, tolerance, and direct current voltage rating.
Why This Calculator Helps
Old capacitors often have faded labels. Dirt, wax, and heat can hide printed markings. A color band decoder reduces mistakes during restoration. It also helps compare a stored spare part with a schematic value. You can enter all six bands, then review the value in pF, nF, µF, and farads. The tool also shows the tolerance window. That range matters because many original parts were not precise.
Reading Direction
Start at the outside foil lead side when that end is known. The first three bands give the capacitance value in MMFD, which equals pF. The first band is the first figure. The second band is the second figure. The third band tells how many zeros follow. The fourth band gives tolerance. The fifth and sixth bands form the voltage rating in hundreds of volts.
Practical Checks
A decoded value is only a label value. Vintage paper capacitors may leak current or drift badly. Always test critical parts with proper instruments before reuse. In power circuits, replace unsafe parts with modern rated capacitors. The optional voltage field helps compare your circuit voltage with the decoded rating. A conservative margin is wise, especially in tube equipment.
Exporting Results
The calculator includes CSV and PDF export buttons. Use CSV when you need spreadsheet records. Use PDF when you want a service sheet. The example table gives common band sets for quick comparison. It is useful when checking several parts on a bench. Keep notes about location, measured value, and replacement choice. Good records help future repairs. They also prevent confusion when two parts share similar colors. This page keeps the layout simple, readable, and focused. The white design leaves room for your notes and photos. Use the result as a guide, then confirm performance under safe workshop conditions before installing the component again.