lm3914 calculation

[Twiggy]

Hey guys, using this schematic (national datasheet), and do not quite understand the calculations for the resistors. Can someone explain to me how I would configure the resistor values to have the full power at 1.5 volts, least at 0v and 0.15 power increments. This is for measuring batteries. thanks in advance, twiggy.

 

[MikeMl]

1.5 = 1.25(1+R2/R1), where 1.5V is your full scale voltage, and 1.25 is the internal reference.

Solving for R2/R1 = 1.5/1.25 - 1 = 0.2

So make R2 = 200Ω and R1=1K

 

[Twiggy]

thanks for your help. very useful.