TweetThe 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
TweetBasic 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
TweetWe’ll begin with a square function, f(t), that has a an amplitude of 1, a start time of 2 seconds and an end time of 4 seconds. Next, a time shift is demonstrated. Here our function is changed from f(t) to f(t-2). Notice that subtracting 2 from t in the function results in a positive [...]
Tags: amplitude, duration, function, graph, scale, shift, signal, time
TweetCalculating hole and electron concentrations 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 [...]
Tags: acceptor, atom, calculate, concentration, donor, electron, hole, junction, n, n-p, n-type, p, p-n, p-type
TweetImportant Amplifier Properties Isolation For the biological subject, against electric shock from the amplifier’s power source(s)–or, how to not kill your patient while taking measurements! For the signal-to-noise ratio (SNR): isolation keeps the (60-Hz mains and other) noise out of the sensor pickup–and out of the amplifier input. One simple way to isolate the input [...]
Tags: AICHo, Amplifier Saturation, Amplifiers, Bandwidth, Biomedical Engineering, Biosignal, DAQ, DAQ Card, Differential Amplifier, Isolation, Pre-Amplifier, Single-Ended
