Chapter 3

What you need to know about real life resistors

In the last chapter we quoted the case of a voltage dropping resistor which dissipated 20 W. Although resistors of this and even higher wattages do appear in many vintage radio sets, most that are employed in them need to be rated at no more than 1 W, and often as little as one-eighth of a watt. Resistance values, however, span a hung range from as little as 10 ohms up to as high as 10 million ohms (10 megohms or MΩ). It is impracticable to make wire-wound resistors of much over 50 000 Ω since the length of wire required would be enormous, the cost prohibitive and the size huge. Fortunately another resistive material is available with which physically small resistors may be mass produced ...

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