When you open up an electronic device, you are confronted with quite a lot of colours on the components (especially when the device has a certain age – smd components unfortunately are less colourful).
“The electronic color code was developed in the early 1920s by the Radio Manufacturers Association (now part of Electronic Industries Alliance (EIA)), and was published as EIA-RS-279. The current international standard is IEC 60062.
Colorbands were commonly used (especially on resistors) because they were easily printed on tiny components, decreasing construction costs. However, there were drawbacks, especially for color blind people. Overheating of a component, or dirt accumulation, may make it impossible to distinguish brown from red from orange. Advances in printing technology have made printed numbers practical for small components, which are often found in modern electronics.”
Resistors, for example, have three bands of colour indicating their value in Ohm – the fourth band indicates how accurate these values are. Knowing their value is essential, even already for basic electronics, because they control the voltage passing through your electrical circuit.
You can learn the values of these colours by heart, or you can use little helpers, who come in several shapes and sizes.
– I’m quite a fan of this resistor calculator:
– There are good looking apps, such as this ElectroDroid.
When you use leds, having the right resistor at hand is very necessary, because when it gets too much power it stops working.
So, of course there are online calculators for leds!
Even thermistors have their own calculator.