As the symbol hints the varistor is a voltage dependent resistor. Primarily it is used for taking care of voltage transients of different shapes. Unlike thermistors it has no practical time delay of its function. R 5.3.1 Function and design Just as thermistors the varistor is fabricated from a compressed ...
R 5.1 NTC THERMISTORS In this section we shall describe some non-linear resistor styles, meaning that they don’t follow Ohm’s law. Simplified, the resistor material consists of doped granule compounds containing various oxides that by means of binders have been pressed to a desired shape and then sintered. The terminals ...
The need for small, adjustable resistors created trim potentiometers. They lack the potentiometer shaft and are operated through an adjustment screw or a rotor. The setting needs to be maintained during handling and environmental influence. Thus, the contact pressure of the wiper is high. The setting stability is specified as ...
According to IEC precision potentiometers are classified as Type 1. They exist in both bushing mount styles and in servo applications. In the latter case high demands are made for rotational life and low torque. Such potentiometers are supplied with ball bearings. If they in addition are sealed against moisture ...
R 4.2.1 Power potentiometers Power potentiometers are as a rule wirewound. They are wound on a ceramic body and lack, due to heat dissipation concerns, encapsulation in casings or housings. Often they have a touch protection of silicone lacquer, cement or enamel and they are readily used as rheostats. If ...
by Stephen Oxley M.Eng C.Eng MIET, TT Electronics UK presented by S.Oxley at the 2nd PCNS 10-13th September 2019, Bucharest, Romania as paper 1.3. Abstract Film resistor technologies have come a long way since metalised glass and cracked carbon films were first offered over eighty years ago as alternatives to ...
R 4 POTENTIOMETERS R 4.1 CONCEPTS AND DEFINITIONS Potentiometers are electromechanical components and therefore exposed not only to the weaknesses of fixed resistors but also to all the failure possibilities of electromechanics. The reliability is comparatively poor. It will be even lower if we try to tool the shafts for ...
R 3.7 CARBON FILM Carbon film resistors sometimes are called surface layer resistors. Better qualities are classified as “stable” with a ΔR/R that will stop at ≤1%. Their role has, to a great extent, been taken over by the metal film but they still have a market, especially as cheap ...
R 3 NON-WIREWOUND RESISTORS R 3.1 OVERVIEW Non-wirewound resistive elements may be produced and arranged in a lot of different ways. We shall present the following types, differentiated by constructional material or specific design: R 3.2 Film resistors, in generalR 3.3 Metal film / thin filmR 3.4 Metal foilR 3.5 ...
R 2 WIREWOUND RESISTORS R 2.1 GENERAL COMMENTS As the name indicates wirewound resistors consist of a resistive wire wound on a bobbin and supplied with a protective coating. Since the resistance wire never can serve as a termination wire because of solderability requirements, it has to be connected to ...
