This digital voltmeter circuit is a saving, easy to use Because it is smaller than a typical circuit, I believe that, after I presented this circuit. You will certainly like it.
This circuit can be used as Versatile. Features of the circuit :
– 3-digit numeric display with LED 7 segment.
– The maximum display +999 mV and the maximum negative-99mV.
– Adjustment measurement range is not limited by the resistance, only two options.
– Using the voltage + 5 V single power supply is not necessary to use the negative circuit pack.
The heart in the working of circuit is IC CA3162E. Which converts analog signals into digital signals in a Dual – slope A / D conversion.
The output of IC will be the multi-plex binary code display type. so easy to build because has the wire to the display is a few.
For the input signal we are divided into two ways to be:
First: 1V.IN for measure the DCVolt that has a voltage not exceeding 1volt.
Second: But for those who want to measure the voltage higher than 1V. Enter the inputs into the Vi point, and change the Rx,Ry as you want.
For example : you would like to the measure rang a maximum of 99.9 Volt you should use the value of Rx=10M, Ry=100K
And in the the measure rang of 999V you should use the Rx=10M and Ry= 10K etc.
The Ry may be calculated from the formula:
Ry = 10,000,000 /(Ei-1)
When the Rx = 10M is fixed.
Ei : is the measure rang as you want.
C2 is a integrating Capacitor.
The parts of this circuit.
IC1______________CA3162E __ A/D converter for 3-digit display
IC2______________CA3161__ BCD to Seven Segment Decoder-Driver
Q1,Q2,Q3_________ BC548___45V 100mA NPN Transistor
R2_______________470ohm__ 1/4W Resistors
Ry_______________See text such as: 100K at 100V
C1_______________0.01uF 63V___Polyester Capacitor
C2_______________0.22uF 63V___Polyester Capacitor
C3_______________0.1uF 63V___Polyester Capacitor
C4_______________100uF 25V Electrolytic Capacitors
Display____________see in circuit.
How to build this project
First of all we make the PCB and placing all components as Figure 3. What to look carefully for is the polarity of the electrolytic capacitors and Diodes, led 7 segment display correctly. Pin of the IC is not an error.
Customization, you should have a reference voltage and the digital volt meter in successful. To compare measurements. And then…
VR1 for adjust the ZERO ADJ , VR2 for adjust the CALIBRATE of the circuit.
This circuit is designed for use with the power supply 6V to 12V by it has the IC3-uA7805 to be the DC voltage regulator 5volt.