Free circuit schematics - wiparat.com

This is simple 3-digits digital volt meter.PIC16F676 used to read analog signal(voltage) and display the value on 3-digits 7-segment. You can apply similar principles to measure DC current with parallel R shunt. [...] Link

First bear it in mind that it is a single digit voltmeter which is 0-9 counts only on the positive side, that is it can measure +0 to +9V DC +/- 1V error. That may not be practical for the cost of the components above. It may be used as a toy logic probe. The [...]