In bipolar junction transistors the factor that determines the sensitivity level of the device to base current, and the amplification level at its collector is called beta or the hFE. This also determines the gain of the device. In other words, if the BJT uses relatively higher current to switch its collector load optimally then […]
Electronics Theory
Field-Effect Transistors (FET)
The field-effect transistor (FET) is an electronic device in which an electric field is used to regulate the flow of current. To implement this a potential difference is applied across the gate and source terminals of the device, which alters the conductivity between the drain and source terminals causing a controlled current to flow across […]
Transistor Common Collector
A BJT common collector amplifier is a circuit in which the collector and the base of the BJT share a common input supply, hence the name common collector. In our previous articles we have learned the other two transistor configurations, namely the common-base and the common-emitter. In this article I have explained the third and […]
Darlington Transistor Calculations
Darlington transistor is a well known and popular connection using a pair of bipolar transistor junction transistor (BJT), designed for operating like an unified “superbeta” transistor. The following diagram shows the details of the connection. Definition A Darlington transistor can be defined as a connection between two BJTs that allows them to form a single […]
How Varactor (Varicap) Diodes Work
A varactor diode, also called varicap, VVC (voltage-variable capacitance, or tuning diode, is a type of semiconductor diode which features a variable voltage-dependent capacitance on its p-n junction when the device is reversed biased. Reverse bias basically means when the diode is subjected to an opposite voltage, meaning a positive voltage at the cathode, and […]
Tunnel Diode – Working and Application Circuit
A tunnel diode is a type of semiconductor diode which features a negative resistance on account of a quantum mechanical effect known as tunneling. In this post I have explained the basic characteristics and working of tunnel diodes, and also a simple application circuit using this device. We will see how a tunnel diode could […]