7 Terminal Square Trimming Potentiometers

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7 Terminal Square Trimming Potentiometers Features

  1. (Single Turn/ Cermet/ Industrial/ Sealed)
  2. (7 Terminal Styles)

7 Terminal Square Trimming Potentiometers Parameters download PDF files Download TSR-3323 - 7 Terminal Square Trimming Potentiometers PDF

7 Terminal Square Trimming Potentiometers - Electrical Characteristics
Standard Resistance Range 10Ω - 2MΩ
Resistance Tolerance ±5%, ±10%
Absolute Minimum Resistance ≤1% R or 2Ω
Contact Resistance Variation CRV≤1%or 2Ω
Insulation Resistance R1≥1GΩ(500Vac)
Withstand Voltage 707Vac
Effective Travel 250°

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Polystyrene Film Capacitors

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In these devices, polystyrene film is used as the dielectric. This type of capacitor is not for use in high frequency circuits, because they are constructed like a coil inside. They are used well in filter circuits or timing circuits which run at several hundred KHz or less.

The component shown on the left has a red color due to the copper leaf used for the electrode. The silver color is due to the use of aluminum foil as the electrode.

  • The device on the left has a height of 10 mm, is 5 mm thick, and is rated 100pF.
  • The device in the middle has a height of 10 mm, 5.7 mm thickness, and is rated 1000pF.
  • The device on the right has a height of 24 mm, is 10 mm thick, and is rated 10000pF.
  • These devices have no polarity.

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Multilayer Ceramic Capacitors

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The multilayer ceramic capacitor has a many-layered dielectric. These capacitors are small in size, and have good temperature and frequency characteristics.

Square wave signals used in digital circuits can have a comparatively high frequency component included.

This capacitor is used to bypass the high frequency to ground.

  • In the photograph, the capacitance of the component on the left is displayed as 104. So, the capacitance is 10 x 104 pF = 0.1 µF. The thickness is 2 mm, the height is 3 mm, the width is 4 mm.
  • The capacitor to the right has a capacitance of 103 (10 x 103 pF = 0.01 µF). The height is 4 mm, the diameter of the round part is 2 mm.
  • These capacitors are not polarized. That is, they have no polarity.

Ceramic Capacitors

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Ceramic capacitors are constructed with materials such as titanium acid barium used as the dielectric. Internally, these capacitors are not constructed as a coil, so they can be used in high frequency applications. Typically, they are used in circuits which bypass high frequency signals to ground.

These capacitors have the shape of a disk. Their capacitance is comparatively small.

  • The capacitor on the left is a 100pF capacitor with a diameter of about 3 mm.
  • The capacitor on the right side is printed with 103, so 10 x 103pF becomes 0.01 µF. The diameter of the disk is about 6 mm.
  • Ceramic capacitors have no polarity.
  • Ceramic capacitors should not be used for analog circuits, because they can distort the signal.

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Farad

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A capacitor's storage potential, or capacitance, is measured in units called farads. A 1-farad capacitor can store one coulomb (coo-lomb) of charge at 1 volt. A coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons. One amp represents a rate of electron flow of 1 coulomb of electrons per second, so a 1-farad capacitor can hold 1 amp-second of electrons at 1 volt.

A 1-farad capacitor would typically be pretty big. It might be as big as a can of tuna or a 1-liter soda bottle, depending on the voltage it can handle. For this reason, capacitors are typically measured in microfarads (millionths of a farad).

To get some perspective on how big a farad is, think about this:

  • A standard alkaline AA battery holds about 2.8 amp-hours.
  • That means that a AA battery can produce 2.8 amps for an hour at 1.5 volts (about 4.2 watt-hours -- a AA battery can light a 4-watt bulb for a little more than an hour).
  • Let's call it 1 volt to make the math easier. To store one AA battery's energy in a capacitor, you would need 3,600 * 2.8 = 10,080 farads to hold it, because an amp-hour is 3,600 amp-seconds.

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Capacitor Circuit

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In an electronic circuit, a capacitor is shown like this:

electrical circuit

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When you connect a capacitor to a battery, here's what happens:

capacitor connected to a battery

  • The plate on the capacitor that attaches to the negative terminal of the battery accepts electrons that the battery is producing.
  • The plate on the capacitor that attaches to the positive terminal of the battery loses electrons to the battery.

History of the Capacitor

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The invention of the capacitor varies somewhat depending on who you ask. There are records that indicate a German scientist named Ewald Georg von Kleist invented the capacitor in November 1745. Several months later Pieter van Musschenbroek, a Dutch professor at the University of Leyden came up with a very similar device in the form of the Leyden jar, which is typically credited as the first capacitor. Since Kleist didn't have detailed records and notes, nor the notoriety of his Dutch counterpart, he's often overlooked as a contributor to the capacitor's evolution. However, over the years, both have been given equal credit as it was established that their research was independent of each other and merely a scientific coincidence.

The Leyden jar was a very simple device. It consisted of a glass jar, half filled with water and lined inside and out with metal foil. The glass acted as the dielectric, although it was thought for a time that water was the key ingredient. There was usually a metal wire or chain driven through a cork in the top of the jar. The chain was then hooked to something that would deliver a charge, most likely a hand-cranked static generator. Once delivered, the jar would hold two equal but opposite charges in equilibrium until they were connected with a wire, producing a slight spark or shock.

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