So my final year project for electronics engineering diploma (2010), was to design and implement a digital multimeter using Atmel 8051 MCU+16×2 LCD and a development board that was supplied by the university.
Schematic Diagram for the external setup of the meter
Schematic Diagram for the Development board(Open source)
Source code: written in Keil Uvision 3 (program has few bugs but works 100%)
Hi, Mpho is my name! 
This Digital Voltmeter is poorly constructed and feels cheap. I used it for a couple of weeks before the 510 connection ripped right out of the device. These post are indeed precious indeed.
Thank you, also look at my other posts they might come in handy one day.