Facts and Figures

• Facts and Figures
• Imperial Standard Wire Gauge
• US Aircraft Plumbing and Wiring Colour Codes
• Scale Equivalents
• Humbrol Equivalents to Testor Colours
• Humbrol Equivalents to British Standard Colours
• Humbrol Equivalents to Federal Standard Colours
• Humbrol Equivalents to R.A.L. Colours
• Humbrol Equivalents to Tamiya Colours
• Humbrol Equivalents to Revell Colours
• Humbrol Equivalents to Gunze Sangyo Colours
• Resistor Colour Codes
• Colour Theory
• Model Railway Scales and Gauges
• Brick Bonds
• Model Trees
• Signal Flags
• Humbrol Equivalents to Citadel Colours
• Humbrol Equivalents to Airfix Colours
• Humbrol Equivalents to Humbrol Authentic Colours

Resistor Colour Codes

Resistor Colour Codes

When I started dabbling in electronics in the early 1980's pretty much all the resistors that we ever got our hands on were of the four band variety. Of the four colour bands used to indicate the resistors value, the first two gave a couple of digits. For example, if they were yellow and violet that gave the number 47. The 3rd band was a multiplier so if our example had a black 3rd we'd be looking at a 47 ohm (47R) resistor while an orange band would indicate 47,000 ohms (a.k.a. 47k). The 4th band specified tolerance. This allowed for variables in the manufacture of the component and if, for example, our 47k resistor had a silver 4th band the resistor could in fact be anywhere between 42,300 and 51,700 ohms!

Back in the 1980's all the resistors I ever saw had a gold or silver 4th band but improvements in manufacturing have made it possible to make cheap resistors to much closer tolerances. This has caused a number of changes:

1. The tolerance is now more usually red or brown to indicate 2% or 1% tolerances.

2. The multiplier may now be gold or silver to indicate values as shown in the table.

3. 5 band resistors are now commonly available.

What this all means in term of component identification is this:

You can't identify which is the last band by looking for the gold or silver one like we used to because it will most probably be red or brown these days and of course so could the 1st band. The way to identify that you are holding the resistor the right way round (for reading the value that is as it doesn't matter which way round it goes into the circuit) is that the spacing between the tolerance band and the others will be slightly greater than the spacing between the other bands.

With 5 band resistors the first three bands give numbers with the 4th being a multiplier and the 5th being the tolerance i.e. you've now got three figure accuracy in the value of the component.