Types of Transistor
A number of transistors types are employed mainly for switching purposes. While others can be employed for both amplification & switching purpose. Below is a listing of the different sorts of transistors:
- Bipolar Junction Transistors – Bipolar junction transistors are made up of 3 areas, the base, the collector & the emitter. There transistors are current controlled. Bipolar junction transistors are of 2 types- PNP & NPN.
- Field Effect Transistors – Field effect transistors are made up of 3 areas namely- a drain, a gate & a source. These are voltage controlled devices. A voltage supplied at the gate controls flow of current from the source to the drain of transistor. Field effect transistors are of two types- JFETs & MOSFETs.
Types of Transistor by Function:
- Small Signal Transistors: Small signal transistors are transistors that are employed mainly to intensify low level signals but can even work well as switches.
- Small Switching Transistors: Small Switching Transistors are transistors that are used primarily as switches but which can also be used as amplifiers. They come in NPN and PNP forms.
- Power Transistors: Power transistors are appropriate for the purpose where a large number of power is being consumed- voltage & current. The transistor’s collector is united with a metal base that behaves like a heat sink to disburse surplus power.
- High Frequency Transistors: RF transistors are transistors that are employed for minute signals that flow at high frequency for high speed switching purposes. High frequency transistors are employed in VHF, HF, CATV, UHF, and MATV amplifier and oscillator purposes.
- Photo-transistors: These transistors are light sensitive. Photo-transistors resembles like a bipolar transistor with its base leg eliminated and substituted with a light-sensitive region.
- Uni-junction Transistors: Uni-junction transistors are three legged transistors that perform entirely as electricity controlled switches; these transistors are not employed as amplifiers.