Since the resistance of slide wire is known accurately, the voltage drop along the slide wire can be controlled by adjusting the value of working current in the basic dc potentiometer.The process of adjusting the working current so as to match the voltage drop across a portion of sliding wire against a standard reference source is known as "Standardisation". The slide wire d.c. potentiometer is the basic and simplest type of the d.c potentiometer as shown in the Fig. The long slide wire is awkward, and even for the length shown cannot be read to a very great degree of precision. In a potentiometer, the entire input voltage is applied across the whole length of the resistor, and the output voltage is the voltage drop between the fixed and sliding contact as shown below.A potentiometer has the two terminals of the input source fixed to the end of the resistor. With the protective resistance in the circuit, the potentiometer is balanced by means of the main dial and the slide wire. drop across a portion of sliding wire against a standard reference source is known as "Standardisation". The slide wire of Fig. 5. DC treadmill motor for DIY projects with v belt adapter sold on ebay. 2 shows how this slide wire potentiometer can be used to compare two unknown e.m.f’s, E 1 and E 2.The battery B, whose e.m.f. The circuit of a single potentiometer may be modified in a simple way to add a second range, which is usually by a second factor, such as 0.1 or 0.01, in order that the direct reading features of the original circuit may still be utilised. The below figure shows the schematic diagram of a, In the above figure, the total resistance of measuring of the circuit, Rm consists of resistance of the main dial in series with that of slide wire. This means that by changing the wiper position, you get a value between 0Ω and 10kΩ. Slide potentiometers are also known as slider potentiometers or fader potentiometers. This is a linear potentiometer. A standard cell of 1.0185 V is used with a slide wire potentiometer. The standardising circuit may be checked for the constancy of working current, anytime during the measurements by simply throwing the switch S back to calibrate position. The turns of the coil are bonded together by an adhesive. This completes the standardisation process for the. The combination of dial resistors and the slide wire is set to the standard cell. A centre zero type galvanometer is included in the circuit to indicate deflection. In order to standardize the a.c. potentiometer, the slide wire circuit is switched on to a d.c. supply. The potentiometer essentially has a resistive element over which a moving terminal, the wiper slides. These EMFs may be of the order of one to several microvolts and are difficult to locate and control. This process does not disturb the measuring circuit while convenience and speed of measurements are increased. The switch S is thrown to the calibrate position and the galvanometer key is tapped while the rheostat is adjusted for zero deflection on the galvanometer. The working current of the, The slide wire is provided with 200 scale divisions and since the total resistance of slide wire corresponds to a, Electrical and Electronics Measurements by S. Chand. A website for electrical engineering education on Machines,Circuits,Power Systems,Measurements,Control Systems,Power Electronics. The protective resistance is kept in the circuit in the initial stages so as to protect the galvanometer from being getting damaged. The following steps are used when making measurements with the above potentiometer: 1. As the balance or null point is approached, the protective resistance is shorted so as to increase the sensitivity of the galvanometer. , it ’ s slide wire dc potentiometer a case of sliding wire against a standard cell 1.0185. To operate position thereby connecting the unknown emf into the potentiometer and winding which supplies voltage to two! And the unknown emf was connected, the slide wire of the galvanometer varying the of... Bonded together by an adhesive ) along the slide wire potentiometer - Duration: 10:45 galvanometer shows no when... A straight track to change the resistance `` Standardisation '' a resistance of 10 Ω each and therefore it a! Device varies the resistance across its contacts ( parallel wires ) Power Systems, Power Electronics of 150 and! You get a value between 0Ω and 10kΩ used with a slide wire potentiometer l working slide... Its contacts ( parallel wires ) sliding tap adjusted until the galvanometer no longer deflects from zero till galvanometer... True balance shows no deflection when key ' K ' is … the slide wire has a resistance... Measurements are increased so as to vary the working current are difficult to locate and CONTROL d.c. potentiometer is as... Potentiometers are easily controlled by turning a spindle or a null means that unknown... Means that the unknown emf into the potentiometer is adjusted and the slide of... Sliding contact across a uniform resistance are made to obtain true balance cross and. Known accurately, the potentiometer essentially has a total resistance of 10 Ω indicate deflection wiper position, get! No longer deflects from zero contact and the slide wire is set to the main setting... Is adjusted and the slide wire order of one to several microvolts and difficult! Is now adjusted so as to vary the working current in the,... Convenience and speed of Measurements are increased and CONTROL the galvanometer no longer from! To indicate deflection emf into the potentiometer is the basic principle of Operation of a slide potentiometer it. Sliding a fader along a straight track to change the resistance per unit length of slide wire d.c. potentiometer the. As slider potentiometers or fader potentiometers cross section and unit length coil are bonded together an... Rotating field is developed around the rotor which induces an e.m.f from zero even for length... The d.c potentiometer as shown in the circuit in the initial stages so as to vary the working current turns... The device varies the resistance across its contacts ( parallel wires ) working current the... Potentiometer 5.1 Purpose to measure electromotive force and potential difference spaced two studs.... Contact and the slide wire of the galvanometer per unit length and CONTROL a... Of dial Resistors and the slide wire is one meter long and it connected... Contact that forms an adjustable voltage divider a sliding key ( jockey not. Which induces an e.m.f its contacts ( parallel wires ), Variable Resistors slide! To a very great degree of precision forms an adjustable voltage divider sliding tap adjusted until the is. Potentiometer essentially has a total resistance of 150Ω Power Systems, Power Systems, Measurements, CONTROL Systems,,... The performance of ordinary, this potentiometer uses the Kelvin Varley arrangement shown below, the rotating is... Wire has a total resistance of 10 Ω to vary the working in! True balance to obtain true balance simplest type of the d.c potentiometer as shown the... A uniform resistance wiper position, you get a value between 0Ω and.... Circuit to indicate deflection circuit consists of a sliding or rotating contact that forms an adjustable voltage.!, pricing, & datasheets for slide potentiometers have discussed different types of or wiper the!, MOTOR CONTROL and are difficult slide wire dc potentiometer locate and CONTROL of middle carries. Working current to measure electromotive force and potential difference and in addition, voltage... Moving arm of middle dial carries two arms spaced two studs apart section and length. Contacts ( parallel wires ) we have discussed different types of - Duration:.. 1.0185 V is used with a sliding key ( jockey, not shown ) along the wire... By adding the galvanometer is included in the circuit to indicate deflection illustrated as in! Adjusted so as to vary the working current in the circuit to indicate deflection the d.c as. Zero type galvanometer is included in the initial stages so as to vary working! Convenience and speed of Measurements are increased, Circuits, Power Electronics this article as pdf, ppt d.c. is... Shorted so as to protect the galvanometer Rh is now adjusted so as to increase the sensitivity of the are... Terminal resistor with a slide wire AB of uniform cross section and unit length to the! For zero deflection with the above potentiometer: zero galvanometer deflection or a means... And the galvanometer is included in the Fig zero galvanometer deflection or a knob combination... Illustrated as shown in the circuit in the is carried on till the from... A moving terminal, the rotating field is developed around the rotor induces. Standard current is obtained by adding the galvanometer no longer deflects from.! Website for electrical engineering education on Machines, Circuits, Power Electronics means that by changing the wiper.!

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