[HomeBrew] Questions about passive components

[R. Blackman]

Hello to group.
Not much activity these days so I thought a discussion would be fun.
Question:

why do components have the 'standard' values that the have?
for example:  resistors have 47 , 470, 4.7K 47K etc,  instead of perhaps 48 
which is easier math  for 12 volts
Why does a 1/4 watt resistor have the value 49.9 instead of 50 ohms? ( just 
checked digikey)
Capacitors:  seem to like the numbers 22, 33  or 68 for example.

does this refer back to the old days of high voltage systems?

Happy to hear any ideas

Have fun

Richard VA3NDO 


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