Frequently Asked Questions

The first row will have a number like 33J, 104Z or 223Z, where first two digits denote significant figures; the last digit denotes the multiplier of 10 in pF. The letter denotes the tolerance, for which you should check the product data sheet. If there is a second row this will be the Manufacturer's Identification.

Examples
         33J = 33 x 10⁰ pF = 33pF
         104Z = 10 x 10⁴ pF = 0.1μF
         223Z = 22 x 10³ pF = 22nF

Many resistors have 4 bands:

• The first band gives the first digit.
• The second band gives the second digit.
• The third band indicates the multiplier (number of zeros).
• The fourth band shows the tolerance of the resistor value
  • Silver ±10%, Gold ±5%, Red ±2%, Brown ±1%
  • Green ±0.5%, Blue ±0.25%, Violet ±0.1%, Grey ±0.05%

It's also common to find 5 Band resistors that will have 3 digits before the multiplier and tolerance, whereas a 6^th Band show a temperature co-efficient.

eg. Brown Green Red Gold = 15 x 10² = 1500Ω also written 1K5

When we write 1K5 the "K" in the middle means thousand and replaces a decimal point that might be missed. Similarly we can use "R" and "M" for other factors, where 2R2 would be 2.2Ω and 5M6 would be 5.6MΩ or 5.6 x 10⁶.

There are a variety of units used, most common is Nm (Newton Meters) but with small values you might see Nmm (Newton millimetres). This is relatively straight forward as there is a factor of 1000 between the two (1m = 1000mm), unfortunately other measures are also common but all are based on distance x force so conversions are not difficult.

In the case of in.oz (inch ounce) or kg.cm (kilogram centimetre) they are often depicted at in.ozf or kgf.cm to show a measure of force rather than mass.

John Piccirillo's "Robotics miniFAQ for Beginners" can be found here as a PDF, updated Aug 2006.

The Robot Competition FAQ can be found here, and contains contains brief summaries of regular robot competitions around the world.