ST2001HI PDF

Мануалы Справочник Программы Радиосамоделки Медтехника Библиотека Транзисторная база данных по радиокомпонентам Небольшая информационная база по зарубежным полевым и биполярным полупроводниковым приборам, создана радиолюбителями для облегчения поиска информации по зарубежным транзисторам, особенно это становится актуально в случае отсутствия доступа к интернету. Типы корпусов современных транзисторов Корпус - это основная и самая габаритная часть конструкции абсолютно любого полупроводникового прибора, выполняющая защитную функцию от внешних воздействий и используемая также для соединения с внешними электрическими цепями с помощью металлических выводов. Типы корпусов зарубежных транзисторов стандартизованы для простоты процесса изготовления и применения изделий в радиолюбительской практике. Число типичных полупроводниковых приборов в настоящее время исчисляется сотнями, если уже не тысячами.

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Note that transistors with built-in damper diodes also are likely to have a base to emitter resistor of about 50 ohms - keep this in mind when testing a HOT with a multimeter - that 50 ohm resistor will look like a shorted junction on the diode test scale. In nearly all the above cases, the devices will plug-in substitute for each other within a category. For designs with larger screen sizes and higher frequencies the device selection is not so straightforward as some designs which split the horizontal deflection and high voltage generation circuitry.

Continuous dissipation is hardly ever the cause of failure. Failure is usually due to some infrequent transient condition. When repairs are made it is wise to cycle through a mode-change sequence. Delays of about 1 min. As a rule, once an engineer has a bad experience with mode change he takes greater care in the small-signal circuitry of his next design. This has led to mode change, in general, becoming more benign in the last couple of years. To "cook" a device by mode changing would take at least 30 mins.

If a device fails during such a sequence the old spit test is good indicator of why a device fails. Also if the device is on a grounded piece of metal as heatsink try adding another radiator twisted vane is my preference.

Some TV manufacturers introduce post production mods to change resistance values to provide more drive into the base, this may be in the base or emitter. Scope the waveform for parasitic high frequency oscillation and check that the waveform looks clean.

Check voltage rails, supply and derived, and that the set is not over scanning. Check all the components around the horizontal output stage, it may be the manufacturer. When looking for suitable transistor replacements it is necessary to look at the main specifications for the transistor. Once the transistor specifications and parameters have been ascertained, it is possible to check for other replacement transistor types with similar parameters that will be able to operate within the circuit in question.

When considering any possible replacement transistors, it is necessary to look at a variety of parameters. These will include the basic parameters of the transistor operation performance. They will also include the environmentally related parameters, and the physical parameters. All these need to be taken into account when choosing a suitable replacement transistor.

The other way around leaving it out entirely will likely result in instant - i. This is because in modern deflection system designs, the damper carries the horizontal yoke current for a significant portion of the scan.

The damper is a special high voltage fast recovery type of diode - a 1Nx type will not work in its place. BTW, many of these HOTs have a D after the part number to indicate that they have the internal damper and include a B-E resistor which may confuse transistor testing of about 50 ohms. However, the D is not a sure indication of an internal damper - nor is its absence an indication of a lack thereof.

The entire part number must be checked to be sure. These may go by the name flyback, high voltage, snubber, or deflection capacitors. When the HOT is shut off, the current flowing in the inductance of the flyback primary and horizontal deflection yoke cannot be stopped instantly. These capacitors provide a place for this current to go and is part of a tuned circuit in combination with the flyback and yoke which needed to accomplish the flyback function. If this capacitor is open or missing, excessive flyback voltage will result probably killing the HOT.

If the HOT does not fail, the result will likely be greatly increased high voltage. For proper operation and continued safety, only proper exact replacements should be used for these parts. Typical HOT Dissipation: Just measuring the actual power dissipation in a HOT is not trivial due to the nasty shapes of the voltage and current waveforms.

A couple of ways of doing this are: Monitor the voltage and current waveforms for the HOT. Mount the HOT and a fixed power resistor on identical heat sinks so that their thermal enviroments are the same. Then, adjust the current through the resistor and thus its power dissipation so that the temperature rise of the heat sinks for the two are equal. It is often surprising that replacing a horizontal output transistor with one that has overall better specifications does not work out - it may run hot and fail.

There is more to characterizing a transistor than just maximum voltage, current, and power dissipation. One important parameter is current gain: Too low a gain for a particular operating point may result in incomplete turn-on during scan resulting in high dissipation. You want the transistor to be in the fully saturated state. A larger HOT is more likely to have a lower current gain.

If you read the app notes put out by the manufacturers like Motorola you will also find that fast turn off based drive negative step is actually not what you want since this traps excess carriers in the high resistivity collector region which leads to continued conduction and heating. The ideal waveform also provide adequate drive during scan but not excessive overdrive and is thus an increasing ramp to account for the increasing collector current during scan.

Characteristics like this are not dealt with by the basic specs but can differ substantially among otherwise similar transistors. Other types are normally only used in very specialist applications. It is important to know what type the transistor is because there is a difference in the base emitter forward bias voltage drop. For germanium it is around 0. The circuit will be designed around a particular voltage drop.

Install the incorrect type and it experience the inverse of all the voltages it would expect and is likely to be destroyed. Possible application types may include: switching, analogue, low power, RF amplifier, low noise, etc.

Put in the correct type and it may not perform well. For example a low power general-purpose transistor is unlikely to work well in a switching application even if it has a high ft or frequency limit. It is often necessary to match the replacement transistor package as closely as possible to enable the transistor to physically fit. Also the package may give an indication of other parameters.

Transistor parameters such as Vceo, etc need to be checked. Although they are slightly different, for all circuit equivalences of this nature these transistor parameters are the same. Choosing a replacement transistor with approximately the same current gain is necessary. Normally it is not a problem to choose a replacement transistor with a higher gain. Often a lower current gain may be acceptable. It is normally important to ensure that the transistor can meet any frequency limits.

Often the package type is a good indication of this. These are the main parameters that are of importance in most applications, but be on the look out for any other transistor parameters that may need to be included in the selection of the replacement transistor. Picking a replacement transistor When choosing a suitable replacement transistor for use within an electronic circuit, there are several stages that must be considered when making the choice.

These can be progressed in a logical order to narrow down the choice and enable the best alternative for the replacement transistor to be made. As bias voltages and other features are different it is necessary to select a replacement transistor with the same material.

The replacement should have the same application if possible. Ensuring with pin-out is the same most but not all transistors have their leads in order - EBC will save many problems with fitting. Current gain values normally vary widely even for transistors of the same type so some variation will be acceptable. Choosing a replacement transistor with a similar can style will often mean that both transistors have a similar power dissipation.

These are normally required when transistors are used in specialist applications. Once the choice of replacement transistor has been made, then it can be installed in the circuit, and the performance checked. In most cases it will operate satisfactorily, but occasionally there may be a problem. If this is the case, it is necessary to re-visit the way in which the choice of the replacement transistor was made and see if any mistakes were made or look for other parameters that may affect the operation of the transistor circuit.

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