The following is an explanation of symbol conventions , voltage polarities and current directions for npn and pnp BJTs. The goal is to help understand these characteristics but not on the physical level of electrons and holes. The following figure shows practical operation of each BJT in the active mode. npn or pnp? When looking [...]
Tags: base, BJT, collector, Current, Electronics, emitter, npn, pnp, transistor, voltage
Basic BJT Equations: It is also important to know that can be modeled as . These equations are not very informative by themselves so a few examples are demonstrated below. In both examples we will assume is very large. What this means for our calculations is . Since we also assume that . Finding missing [...]
Tags: alpha, base, beta, bipolar, BJT, collector, Current, emitter, junction, npn, pnp, transistor, voltage
Sometimes it can be complicated understanding and calculating hole and electron concentrations. My intent in this article is to briefly, but thoroughly describe what the variables used in these calculations mean and how to use them. To begin I will introduce our variables: concentration of free electrons (donors) concentration of holes (acceptors) = number of [...]
Tags: acceptor, atom, calculate, concentration, donor, electron, hole, junction, n, n-p, n-type, p, p-n, p-type
The 3 common methods of describing a point in a three dimensional coordinate system are Cartesian, Cylindrical and Spherical. The most simple is Cartesian but certain teachers find it necessary to use the others. There are a few simple conversions between them but first it is necessary to know their notation. Cartesian: Cylindrical: Spherical: In [...]
Tags: cartesian coordinates, cartesian to cylindrical conversion, cartesian to spherical conversion, cylindrical coordinates, spherical coordinates
Suppose you are interested in finding the unit vector between two points, and , which are described in cartesian coordinates as and , respectively. You would begin by finding the vector between these two points. The direction of this vector may be important so look for key words such as . Once we have established [...]
Tags: find unit vector, unit vector, unit vector between two points, vector
