5/1/2021 0 Comments All Transistor Data
Choosing a replacement transistor with a similar can style will often mean that both transistors have a similar power dissipation.Either the type of transistor may not be to hand, or it may not be available.
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. 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. Their specifications are not particularly exacting and a variety of general purpose transistors could be used. Today, the performance of even general purpose transistors is exceedingly high and they can be used in a variety of applications. Their specifications need to be examined more closely to ensure that any substitutes will have a similar specification. Other types are normally only used in very specialist applications. For germanium it is around 0.2 - 0.3 volts and for silicon it is around 0.6 volts. 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. 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. Although they are slightly different, for all circuit equivalences of this nature these transistor parameters are the same. Normally it is not a problem to choose a replacement transistor with a higher gain. It is normally important to ensure that the transistor can meet any frequency limits. 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. Differences in the package for small signal transistors is not normally an issue, but for larger ones where there may be heatsinks, etc involved, different packages can cause significant issues. For many transistors the pinout is EBC, but there are other configurations for the pinout that can easily trap many people. Current gain values normally vary widely even for transistors of the same type so some variation will be acceptable. Dont go for a transistor with a much higher Ft as this may increase the risk of oscillation.
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