Types of Digital Voltmeter

Here are the different types of digital voltmeters:

• Ramp Type Digital Voltmeter
• Integrating Type Digital Voltmeter
• Successive Approximation Digital Voltmeter
• Dual Slope Integrating Digital Voltmeter

Ramp Type Digital Voltmeter

There are circuits that generate output signals in the shape of a ramp. The voltmeter used for measuring such ramp signals in Ramp type digital voltmeter. Timing plays an important role in these type of signals .The name of voltmeter is mainly because it measures ramped up signals.

Working: The voltage is measured by providing an unknown input signal to the ranging and attenuation .Depending on the needs ,the signal is attenuated or made stronger by amplification. The ramp generator is a device which generates a positive or a negative ramp and our unknown signal is compared to it. The comparator compares input signal to the ramp signal. If the input voltage matches with ramp voltage then gate is opened with the pulse and after the ramp signal reaches 0 ,the gate is closed. The time period between two events is called gating time interval. This generates the ramp voltage

Integrating Type Digital Voltmeter

This voltmeter measures exact value of input corresponding to the constant of time. This circuit usually uses a voltage-to-frequency converter device which works on the feedback control system. The main characteristic of this voltmeter is that the output from the integrator is compared with the fixed level voltage of reference source.

Working: In this, as soon as the input voltage is applied, the output voltage begins to increase which fed to level detector. After the output voltage reaches a certain value, detector sends a pulse to pulse generator gate. The integrator output is compared to fixed level voltage of the internal reference source resulting in an output pulse. This output pulse from level detector. This pulse opens gate which passes pulse from oscillator to pulse generator. The pulse generator like a Schmitt trigger , generates pulses with fixed width and amplitude .So for each wave a pulse is generated which helps to determine the input voltage.

Successive Approximation Digital Voltmeter

In this voltmeter the output of digital to analog convertor with a certain unknown reference voltage. This meter can measure up to 100 readings per second. The voltmeter uses an amplifier to choose a required range of input voltage and minimize the noise which can cause distortion.

Working: The input amplifier of this device helps to choose a range of input voltage and eliminates any noise. The input is then sent to comparator through an S/H circuit. The comparator generates a signal when it receives the analog signal. This is further sent to AND gat whose output become one if and only if output of comparator is positive. In the end , a digitized digital signal is generated from control registers giving us the required voltage.

Dual Slope Integrating Digital Voltmeter

It consist of an integrator circuit which takes the unknown input for certain time measured using a clock. The circuit consist of comparators ,capacitors ,clock and counters which generate the reference voltage with time. In this way we can measure the required voltage.

Working: In this, the integrator circuit receives an input signal for a specific period of time which is measured using clock frequency. During this time, the capacitor gets charged and the charge is proportional to the input voltage. At the end of this time, the switch is shifted from input voltage to a reference voltage and the charging of capacitor decreases creating a downward linear ramp voltage. This generates the required voltage.

A voltmeter is a significant device used in electronics engineering for measuring potential developed across various devices. Depending on the requirements these voltmeters can be designed into two types that being digital and analog. In this article, we will briefly discuss the two types of voltmeters. Later we will study about digital voltmeter and the working principle behind it. We will also see the block diagram of a digital voltmeter and how it works. The digital voltmeter can further be divided into certain types and we will discuss them too. This description will include talking about their specifications as well. After the discussion, we will talk about the advantages and disadvantages of digital voltmeters which are considered while using digital voltmeters in some real-life appliances. This will conclude the article with some Frequently Asked Questions for user reference.