Doubt in oscilloscope controls

[gcshyamsundhar]

Hi,
In oscilloscopes, there is this vertical scaling knob. I know the functioning of this knob. But what is the reason behind the divisions which are present in it ? In all the oscilloscopes I can find only 1,2 and 5 and their multiplicities. Is there any reason for this ?

 

[Ow@i$]

if you know the functioning than you shouldn't be asking that . Anyways vertical scaling knob is for amplitude setting, lets say i want to measure a 5V signal, if the knob is set at 5v/div than my signal level would not exceed one vertical block since it is 5v/div but if i change it to 2v/div the signal remains the same only now it will be displayed over 2 and a half vertical block.

 

[betwixt]

If you mean why were 1, 2 and 5 specifically chosen as the divider ratio numbers, I would guess because they are easy number to work with. When reading the graticule on the sceen it is easy to do the mental arithmetic when those numbers are used. Technically there is no reason why other divisors couldn't be used instead but it would be less convenient. Some very old oscilloscopes used x1, x10, x100 but the large jumps made it difficult to find a good compromise between scaling to fit the screen and accuracy of reading against the graticule.

Brian.

 

[Dominik Przyborowski]

1x, 2x and 5x multiplication is a typical octave logarytmic scale. The digital scopes provides also fine tunning, i.e. 20mV for 1V/div coarse scale.