Technical articles on Electronics and Electrical Engineering topics focused on Basics of EE, Electronic components, power systems and equipment used for generation, transmission, operation, and controls of electricity.
If some percentage of an amplifier’s output signal is connected to the input, so that the amplifier amplifies part of its own output signal, we have what is known as feedback. Feedback comes in two varieties: positive (also called regenerative), and negative (also called degenerative). Positive feedback reinforces the direction of an amplifier’s output voltage change, while negative feedback does just the … Read more
Stable emitter bias requires a low voltage base bias supply, Figure below. The alternative to a base supply VBB is a voltage divider based on the collector supply VCC. The design technique is to first work out an emitter-bias design, Then convert it to the voltage divider bias configuration by using Thevenin’s Theorem. [TK1] The steps are shown graphically … Read more
Inserting a resistor RE in the emitter circuit as in Figure below causes degeneration, also known as negative feedback. This opposes a change in emitter current IE due to temperature changes, resistor tolerances, beta variation, or power supply tolerance. Typical tolerances are as follows: resistor— 5%, beta— 100-300, power supply— 5%. Why might the emitter resistor stabilize a change in … Read more
Variations in bias due to temperature and beta may be reduced by moving the VBB end of the base-bias resistor to the collector as in Figure below. If the emitter current were to increase, the voltage drop across RC increases, decreasing VC, decreasing IB fed back to the base. This, in turn, decreases the emitter current, correcting the original … Read more
The simplest biasing applies a base-bias resistor between the base and a base battery VBB. It is convenient to use the existing VCC supply instead of a new bias supply. An example of an audio amplifier stage using base-biasing is “Crystal radio with one transistor . . . ” crystal radio, Ch 9 . Note the resistor from the base … Read more
In the common-emitter article, we saw a SPICE analysis where the output waveform resembled a half-wave rectified shape: only half of the input waveform was reproduced, with the other half being completely cut off. Since our purpose at that time was to reproduce the entire waveshape, this constituted a problem. The solution to this problem … Read more
The cascode amplifier is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage. In this post you’ll learn basic concepts and fundamentals of cascode amplifier. While the C-B (common-base) amplifier is known for wider bandwidth than the C-E (common-emitter) configuration, the low input impedance (10s of Ω) of C-B is … Read more
The Raspberry Pi is a small computer that can do a lot of things. You can use it to design a telescope, can make robots of it, can plug it into a monitor, and attach a keyboard and mouse. In this list, we have compiled 50+ Raspberry Pi Projects. You can take these as project … Read more
