This is a link to your displays you are using. Use the data sheets and you will understand, as pointed out, why it is very important to use the parts called out in the drawing, especially the capacitor values. The power supply for this circuit is +5V. Because it is high technology with single IC on 7 segment LED. Here is the schematic diagram of digital DC voltmeter built based IC ICL7107. You may use 9V battery and then use regulator IC LM7805 to achieve 5V stabilized voltage. This circuit will be good to display your power supply output.
Here we design a analog to digital converter working as a digital voltmeter using a low power three and half digit A/D converter ICL7107 having internal 7 segment decoders, display drivers, a reference and a clock. LM3914 is a 10 stage voltmeter that means it shows variations in 10 bit mode. This Voltmeter Ammeter was designed to measure output voltage of 0-70V / 0-500V with 100mV resolution and 0-10A or more current with 10mA resolution. This circuit will be good to display your power supply output. Digital voltmeter circuit diagram using ICL7107 / 7106 with PCB Let's build Simple ICL7017 digital voltmeter circuit easy to build and cheap. Simple Digital Voltmeter Circuit Diagram using ICL7107 In this project we build a low cost and accurate Digital Voltmeter circuit on PCB using a popular IC for voltage measurement namely ICL7107/CS7107. A typical digital voltmeter consists of a analog to digital converter and a digital display. The chip senses the measuring input voltage as a parameter and compares it with reference, every time the voltage crosses the certain part of reference the corresponding LED glows. The power supply for this circuit is +5V. Here is the schematic diagram of digital DC voltmeter built based IC ICL7107. You may use 9V battery and then use regulator IC LM7805 to achieve 5V stabilized voltage. This is a link to your datasheet for the ICL7107 chip you are using.

The power supply for this circuit is +5V. You may use 9V battery and then use regulator IC LM7805 to achieve 5V stabilized voltage. The power supply for this circuit is +5V.
Here is the schematic diagram of digital DC voltmeter built based IC ICL7107. Components List: R1 = …

It is a perfect addition to any DIY laboratory power supply, battery chargers and other electronic projects where voltage and current consumption must be monitored. Here is the schematic diagram of digital DC voltmeter built based IC ICL7107. You may use 9V battery and then use regulator IC LM7805 to achieve 5V stabilized voltage. Circuit Diagram of Digital Voltmeter