A simple bargraph voltmeter can be built using 2×16 LCD or compatible VFD display. For Arduino version click here. This design utilizes PIC16F877 microcontroller and its ADC block to convert 0 – 5V input voltage to a binary number shown as active segments on the display. In this particular design I’ve connected CU16025-UW6J VFD 2×16 Character VFD display
Input voltage can be increased by using a simple resistor voltage divider. Just make sure that a full scale produces 255 in decimal in ADRESH after ADC conversion or the code will behave incorrectly. In some cases you can normalize the converted result by factor of 2 using rotate command (Rotate Left or Right to multiply or divide the number by 2). Here is a design schematic. Assembly source code can be downloaded here.
You can see the voltage bargraph operation in the short video. Analog input AN1 (Pin 3 of PIC) is connected to a variable power supply.