#28 VOLT METER SERIES#

The combination of a series resistance with the moving-coil meter movement forms a DC voltmeter which can give accurate results once calibrated. This is helpful for measuring voltage of either polarity.Īlthough this PMMC meter movement responds linearly to the flow of current in the moving coil, it can be adapted for measuring voltage by the addition of a resistance in series with the coils movement. Some meter movements have a spring-centered pointer with the zero rest position being in the middle of the scale allowing for pointer movement in both directions.

Generally the pointer movement is between zero on the left and full-scale deflection (FSD) at the far right of the scale. Thus the pointer of a galvanometer moves in response to current.Ĭommonly thin helical watch movement type damping springs are used to control the angle of deflection preventing oscillations or rapid movements which could damage the pointer as well as keeping the movement of the coil in rest when no current passes through the coil. Generally there is a pointer, or needle, connected to the coil so the movement of the coil causes the pointer to be deflected over a linear scale to indicate the value being measured with the deflection angle being proportional to the input current. The amount by which the electromagnetic coil moves, called “deflection”, is proportional to the strength of current flowing through the coil needed to produce the magnetic field required to deflect the needle. Voltmeters can be used to measure the voltage drop across a single component or supply, or they can be used to measure the sum of voltage drops across two or more points or components within a circuit. To measure a voltage (potential difference), a voltmeter must be connected in parallel with the component whose voltage you wish to measure. Voltmeters can also be used to measure DC voltage as well as sinusoidal AC voltages but the introduction of a voltmeter as a measuring instrument into a circuit can interfere with its steady state conditions.Īs its names implies, a “Voltmeter” is an instrument used for measuring voltage (V), that is the potential difference present between any two points within a circuit. Voltmeters used for the measurement of voltage come in many shapes and sizes, either analogue or digital, or as part of a digital multimeter more commonly used today. When analysing the operation of electrical and electronic circuits, or trying to understand why a circuit does not work as expected, eventually you will need to use a Voltmeter to measure the various voltage levels.

28 volt meter