The best tips for buying a transistor begin with knowing the right transistor characteristics and types of transistors for the electronic purpose. This means comparing relevant technical information to the needs of the electronic job, such as which transistor schematic to use and which kind of transistor array is appropriate. The right transistor brand can also be important, but most transistors are well made and inexpensive, so technical specifications are usually more important than brand. Cost, and particularly shipping cost, is another comparison item.
When buying a transistor, an electronic conductor that has three connecting prongs that attach to an external circuit will be needed. Many transistors will already be embedded in an integrated circuit, but transistors can still be purchased on their own, and they are still useful for many do-it-yourself and professional electronic jobs. Whether the do-it-yourselfer is an electronics expert or amateur hobbyist, it's essential to know which types of transistors will work best, which might take some research. A lot of research can be done online, and much can be gleaned from manuals for particular electronic parts. Useful instructional materials may also be found in the local library.
Transistors are typically used as electronic switches or amplifiers in basic electronic equipment, which means they're manufactured in massive quantities. Due to the huge number of transistors produced in factories around the world, they're easy to find in any local electronics store or on the Internet. Transistor are typically inexpensive — the cost of shipping may turn out to be more expensive than the item itself. Transistors are even less expensive when purchased in bulk.
When looking for different types of transistors, there are various key words that can help determine what the need, including surface mount, low power, and high frequency. Production materials range from graphene and germanium to gallium arsenide or silicon carbide, but more important concerns relate to polarity, maximum power rating, and operating frequency. Transistor performance is connected to a number of factors such as gain, current, and voltage, so performance should match with the job, be it a switch, some kind of audio use, a pair matching job, or just something general purpose. The amplification factor is another consideration. Depending on how technical the job is, when buying a transistor, it can be important to read all of the specifications.
Other considerations include whether a field transistor or a planar transistor is needed. Field-effect transistors, which are voltage driven, are used for efficient applications that require low-noise performance and faster response time. Planar transistors are manufactured differently. They are sometimes cheaper, and are more likely to be part of an integrated circuit. In both cases, transistors are usually relatively inexpensive.