A low-cost yet efficient digitizer, suitable for a non-intrusive ac voltage probe will be presented in this talk. The existing measurement scheme for such a probe requires an interfacing circuit, an analog-to-digital converter followed by a processor to compute fast Fourier transform (FFT) to obtain an output. A less complex scheme that operates based on the dual-slope analog-to-digital conversion technique will be presented in the talk. The output has negligible sensitivity to the variations in the circuit parameters of the probe. The proposed scheme has a simple compensation approach to accurately obtain the fundamental of the unknown voltage, even if it has a significant 3rd harmonic component. A prototype of the proposed scheme has been designed, developed, and interfaced with a laboratory-made non-intrusive ac voltage probe and tested for 0 600 V, at two frequencies, 50 Hz and 60 Hz. The output of the digitizer is linear, with worst-case non-linearity of 0.26%. The effective number of bits observed for the prototype were 11.16 and 11.85 for 50 Hz and 60 Hz measurement respectively. The details will be presented in the talk.