RESISTORS 



watts — and this is probably their most important advantage. A possible 

 disadvantage of the wirewound type is the fact that control takes place in 

 discrete steps, whereas with a carbon component in good condition the 

 resistance is varied smoothly. 



The voltage rating of variable resistors, whether of wirewound or carbon 

 type, ranges from about 250 V for the miniature types to 500 for the standard 

 sizes. 



Towards the end of their life, variable resistors tend to become 'noisy'. 

 This is due to erratic contact between the slider and the track, the result of 

 wear, or it may — in the case of high value wirewound components — be due 

 to an intermittent open circuit in the track itself; the fine wire fails some- 

 where, perhaps due to corrosion, and the butting ends are now forced together, 

 now parted, by slight movements imparted from the slider. 



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