Using ICL7107 digital voltmeter circuit diagram

The working of this electronic circuit is very simple. The measured voltage is converted into a digital equivalent by the IC's internal ADC , then this digital equivalent is decoded in a seven-segment format and then displayed. The ADC used in ICL7107 is a dual integrating ADC. The process happening inside our ADC can be expressed as follows. For a fixed period of time the voltage to be measured is synthesized to obtain a slope of the integrator output. A known reference voltage of opposite polarity is applied to the input of the integrator and allowed to ramp until the integrator's output goes to zero. The time required for the negative slope to reach zero is measured in clock cycles of the IC, which will be directly proportional to the voltage measured. In simple terms, the input voltage is compared to an internal reference voltage and the result is converted to a digital format.

Resistors R2 and C1 are used for the IC's internal clock frequency setting. Capacitor C2 causes fluctuations in the internal reference voltage and increases the stability of the voltmeter within the control range of the display.R4. The rightmost 3 monitors are connected so that they can display all the figures. The leftmost shows the connection, which can be shown as "1" and "-". PIN5 (point) is connected to ground, only the third one shows that its position needs to be changed when you change the range of the voltmeter by changing R4. (R4 = 1.2K provides 0 - 20V range, R4 = 12K provides 0 - 200V range).

Circuit diagram

Precautions

Good quality printed circuit board assembled circuit.

The circuit can be powered from dual supplies of A+/_5V.

Correction circuit, power up and short term input terminals. Then adjust R6 so that the display shows 0V.

ICL7107 is a CMOS device and is very sensitive to static electricity. Try to avoid touching IC pins with bare hands.

Seven-segment displays must be of the common-anode type.