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PTC Thermistors: Positive Temperature Coefficient

On September 5, 2017, in Capacitor, Electrode Products, by Lambert

The positive temperature coefficient, PTC thermistor has two types: silistor & switching PTC have very different characteristics.

 

As the name indicates a positive temperature coefficient, PTC thermistor has a response in which the resistance rises with increasing temperature.

 

There are two types of PTC thermistor which have very different characteristics, one showing a linear increase, whilst the other shows a sudden change in resistance.

 

PTC thermistor outline

 

PTC thermistors can be divided into two types according to their structure and the materials used. The two types of PTC thermistor have very different characteristics:

 

  • Switching PTC thermistor:

This form of PTC thermistor is used in heaters, sensors and specialized versions are also used as resettable fuses. Switching type NTC thermistors have a highly non-linear curve. The resistance at first falls slightly with increasing temperature, and then at a critical temperature the resistance increases dramatically, thereby acting virtually as a switch. This makes it ideal in many protection devices.

  • Silistor:

The silistor PTC thermistor uses a semiconductor as its base material and it is characterized by a linear characteristic and as a result, the silistor is used in temperature sensors. The silistor PTC thermistor is generally manufactured from doped silicon, the level of doping determining the exact characteristics.

 

Switching PTC thermistor basics

 

As the switching PTC thermistor is very widely used form, it warrants further explanation as it has an unusual characteristic.

 

Switching PTC thermistors are typically fabricated from polycrystalline materials including barium carbonate or titanium oxide with added materials including tantalum, silica, or manganese, etc.

 

The materials are mixed and ground to fine powders and finally compressed into the required shapes before being sintered. Contacts are then added and the thermistor is encapsulated.

 

The characteristic of the switching PTC thermistor shows that the device has a highly non-linear characteristic. As the temperature increases, the resistance first decreases, then rising slightly before it reaches a critical temperature, TC. At the critical temperature the resistance increases sharply for any increase in temperature, before finally leveling off and falling slightly.

 

A similar type of device is known as a Polymer PTC. These devices consist of a plastic element into which carbon grains are embedded. When cool, the carbon is able to conduct electricity, but as the temperature increase the carbon grains move further away as a result of expansion and conduction falls rapidly. In this way the device acts like a switch in the same way as the more traditional PTC thermistors.

 

PTC thermistor operational modes

 

There are two main ways in which switching PTC thermistors are generally used.

 

  • Self-heating mode:

When used in the self-heating mode, current is passed through the thermistor, often in series with the item being controlled. As it heats up as a result of the current, it reaches a point where the critical temperature is reached and the resistance increases significantly. In this way it operates in a self-heating mode and can be used as a safety cut-out or regulator.

 

  • Sensor mode:

In this mode, a minimum amount of current is passed through the device and PTC thermistor senses the surrounding temperature. Keeping the current to a minimum ensures the self-heating effect is negligible and only the surrounding temperature affects the device. As the surroundings heat the device it may reach its critical temperature at which point the resistance will significantly increase.

 

Switching PTC thermistor applications

 

Switching thermistors are a very useful form of electronic component. It can perform functions with a single component that would require far more complex circuitry should any other technique be used.

 

  • In-rush protection:

Some electrical items like motors and transformers have a large surge of current at switch on. This gives rise to very high peaks of current which can cause spikes on the power line, or cause damage in some instances. PTC thermistors can be used to reduce the level of the inrush current and thereby prevent the spikes or damage occurring.

 

  • Overcurrent protection:

In this application, the PTC thermistor is placed in series with the load and uses the self-heating effect. The current taken under normal conditions should enable the thermistor to operate in its flat resistance curve area. However if an over-current condition arises, then the thermistor will carry more current and the temperature will rise more causing it to rise beyond the critical temperature when the resistance will rise significantly causing the current to drop.

 

PTC thermistor circuit symbol

 

It is sometimes necessary to indicate the type of thermistor being used on a circuit diagram. Accordingly the IEC have a special PTC thermistor circuit symbol that can be used.

 

As seen the circuit symbol utilizes the characters +t° to give an indication of the positive temperature coefficient.

 

Positive temperature coefficient, PTC thermistors are used in many electronic circuits and for a variety of functions. It is essential to check that the correct type is selected for any given circuit to ensure that its characteristic meets the requirements.

 

Zonkas is the experienced and reliable manufacturer of specializing in capacitor, inductor, and transformer. If you are still interested in PTC thermistors, welcome to visit the website of Zonkas.

 

 

Article Source: https://www.electronics-notes.com/articles/electronic_components/resistors/thermistor-ptc-positive-temperature-coefficient.php

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Overview of Power Capacitors

On October 4, 2016, in Capacitor, by Lambert

What are they?

 

Power capacitors work by acting as a reserve power bank; they store the charge rather than being the source of power such as the battery. When you are listening to your music, and playing a heavy sub-bass note, the power will draw from the capacitor rather than from the battery so to ensure that the rest of the car will not be starved of power i.e. the headlights dimming. It will act as a buffer so that that the power being delivered to the amplifiers will not drop below the recommended voltages and be steady therefore reducing the risk of damage to the components.

 

So what power capacitor to choose?

 

After doing a bit of research, the general rule seems to be 1 farad per 1000 watts of power that your system is running at. So using that, a 1.5 farad power capacitor should be ideally suited to a 1500 watt system. There is a large selection of power capacitors available out there, for example, this power capacitor is a 2 farad power capacitor designed for smaller systems, this is not to say however that it will have a reduction in performance, however for those systems that require more power, a power capacitor with a higher farad will be able to deliver for longer and will usually be of a higher build quality.

 

How to install the capacitor

 

Ideally the capacitor needs to be installed as close to the amplifiers as possible. The capacitor requires a 12 volt positive from the battery and a separate ground, to the amplifier; so that the 12 volt positive is ‘inline’ with the terminal from the battery and the amplifier. The amplifier 12 volt positive is then taken from the capacitor while the amplifier is usually grounded separately as it is important to use as short a ground cable as possible to reduce any potential ground interference.

 

When you need to consider other alternatives

 

Power capacitors will not always be of help when you are listening to music, if the lights for example dim down, and stay dim, this indicates there is a deficiency of power and there are other methods of solving the problem, it could potentially be that the battery is not able to generate a charge sufficient enough to meet the demands, so installing a higher cranking battery is usually the common solution however it is possible that upgrading “The Big Three” may also solve the issue(see below for more details). It is also important to check that the current alternator can produce a charge that will be sufficient with a larger battery.

 

‘The Big Three’

 

The big three is a popular upgrade. It consists of upgrading three wires in the car to ones that are much thicker. As a result of using much thicker wire, more current is allowed to flow through; hence the overall effect seen will be that the voltage running through the car will be higher. The three wires that are upgraded are the wire from the alternator to the battery, the engine ground to the chassis and the battery ground to the chassis. It is common, but not always, that people will choose 0 gauge power wire when going about the big three upgrade. This is vital again to ensure that the voltage delivered to the amplifiers does not drop so low that the risk of damage is possible.

 

Conclusion

 

So in conclusion, there is no hard or fast answer to if a capacitor is necessary or not. However capacitors may have benefits if used appropriately. There are large selections of capacitors; some come with digital volt meters, distribution blocks etc., while others are purely chosen for aesthetic pleasure, I myself went for a 4 farad power capacitor with a built in digital volt meter with an LCD display so that it was something I was able to display and looks pretty damn cool.

 

If you need more details about power capacitors and capacitor supplier, welcome to visit our website and feel free to send inquiries to YUHCHANG – the outstanding and professional power capacitor manufacturer in Taiwan.

 

 

Article Source: http://EzineArticles.com/expert/Neil_Patel/563675

 

Article Source: http://EzineArticles.com/3791870

 

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An Introduction to Capacitors and Types of Capacitors

On November 5, 2015, in Capacitor, by Lambert

A capacitor is a device used in the field of electronics that is capable of storing energy and sustaining one electric field. It consists of a pair of surfaces that are conductive, usually in the form of sheets or plates, in a position to influence the total (i.e. the electric field of all the field lines that start from one electric device and connect to another) field separated by a medium that is dielectric or vacuum. These plates, subjected to a potential difference, acquire a given electric charge, one positive and the other negative, with the total charge of zero variation.

Although from the physical point of view a capacitor stores no charge or power, but simply mechanical energy that is latent; when introduced into a circuit it behaves in practice as an element that is able to store the electrical energy it receives during the charging period, the same energy yield during the period after discharge. Due to this particular characteristic, capacitors are widely used in the field of electronics to boost the capacity of electrical devices. There are a wide variety of capacitors available in the market and they are used for commercial as well as domestic purposes.

The different types of capacitors are as follows:

Variable capacitor – These capacitors typically consist of a dielectric parallel plate and encapsulated in glass. As their electric permittivity is unity, they have a very small capacity. They are used in radio and aviation radars because of which they are regarded as very important in the field of aviation.

Mica capacitors – The mica capacitors have several properties that make them suitable for things that require a dielectric capacitor. They suffer low losses, can be wrapped in thin sheets, withstands high temperatures and are not degraded by oxidation or moisture. Aluminum is deposited on one side of the mica capacitors, forming an armature. Several of these sheets are stacked alternately by welding the ends to each of the terminals. These capacitors work well at high frequencies and high voltages, but are expensive and are gradually being replaced by other types.

Paper capacitors – These capacitors consist of waxed paper dielectric, and are subjected to any other treatment that reduces their hygroscopic and increases isolation. They are made of two strips of paper that help to prevent the pores that may arise. They are very useful in devices that require handling high voltage electricity. The paper capacitors have applications in industrial environments.

Metalized film capacitors – They are also known as self-healing capacitors. When they are faced with an overload that exceeds the dielectric strength of the capacitor, the paper tears at some point, causing a short circuit between the plates, but this short causes high current density in the torn area. This current melts the thin aluminum layer surrounding the circuit, restoring the insulation between the plates.

Electrolytic capacitors – It is a type of capacitor that uses an electrolyte, which acts as a cathode. With proper tension, the electrolyte deposits an insulating layer (which is generally a very thin layer of aluminum oxide) on the second armature or anode, thus achieving very high capacities. They cannot be operated with AC power.

Varying dielectric capacitor – These types of capacitors have a movable armature which rotates about an axis. The profile of the armature is normally such that the capacitance change is proportional to the logarithm of the rotating angle. They are used in different industrial devices that require a lot of electricity.

Please visit newsmartcom.com, if you are looking for a capacitor for sale.

Article Source: http://EzineArticles.com/expert/Rajot_Chakraborty/1170702

Article Source: http://EzineArticles.com/8972138

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Inductors and Coils Manufacturer – Zonkas Electronic

On May 14, 2015, in Capacitor, by Lambert

Taiwan Inductor and Capacitor Manufacturer & Supplier

Established in 1982, Taiwan Zonkas is a professional capacitor manufacturer. It manufactures ceramic capacitor, film capacitors, electrolytic capacitor, multilayer ceramic capacitors, mini box capacitor and more. Now, Zonkas Electronic have specialized workshops for manufacturing inductors and transformers. Except inductors and capacitos, Zonkas also provide total solution service for other components.

Equipped with specialized production and inspection equipment, Zonkas also strictly carry out the ISO9001 standard. Now Zonkas have obtained UL, VDE, ENEC, NEMKO, CQC, EK certifications.
And Zonkas’s products, inductors and capacitors sell well in such
countries and regions as Europe, North America and South America.

Zonkas Electronic Co., Ltd.
http://www.zonkas-cap.com/
No.13, Ln. 65, Fuya Rd., Xitun Dist., Taichung City 40764, Taiwan
TEL:886-4-24613820
FAX:886-4-24612387

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