Question

A 200 mV full scale dual-slope 3 ½ digit DMM has a reference voltage of 100 mV and a first integration time of 100 ms. For an input of [100 + 10  Cos (100πt)] mV, the conversion time (without taking the auto-zero phase time into consideration) in millisecond is______.

Answer 1

Given that, V_ref = 100 mV

T₁ = 100 msec

V­_in = 100 mV

We know that,

V_in T₁ = V_ref T₂

⇒ (100) (100) = (100) (T₂)

⇒ T₂ = 100 msec

Total conversion time

T = T₁ + T₂

T = 100 + 100 = 200 ms