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Several Announcements and another Qucs Video.

Qucs video Part 5

This post is an announcement of several things. As usual I am going to change direction for awhile for several reasons. First the Big Announcement. Create-and-make is the featured website for this week on an outstanding Website for the Electrical Engineering Community, EEWeb.com, A link to the feature and the

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Bipolar Junction Transistor DC Biasing Calculations Example.

The model of the circuit we are biasing.

It is Number Crunching Time! Tonight we set the DC Bias of the circuit shown in the first diagram. Once we do that we will run several Qucs simulations of the circuit with the numbers we calculate. We will do those simulations with different values for

Continue reading Bipolar Junction Transistor DC Biasing Calculations Example.

Negative Feedback to compensate for Beta Variation in BJTs.

Negative FB Biasing.

In the last post, “Using the Transistor Model – Our first circuit“, the wide tolerance of β (hFE) in the transistor specifications is making life complicated. “Complicate our life will ya!” We will fix the problem by complicating the circuit to reduce the complications. Seriously, we will add several more resistors

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Using the Transistor D.C. Model – Our first circuit.

The first circuit we will analyse.

In the post “The Basic DC Model for a NPN Bipolar Junction Transistor” we came up with a generic model for a transistor and in the last post “Reading a Datasheet for our DC Transistor Model Parameters” we assigned values to the parts of the model based on

Continue reading Using the Transistor D.C. Model – Our first circuit.

Reading a Datasheet for our DC Transistor model parameters.

The model for the active region

We have created the form of our DC model for our transistor in the last post, “The Basic DC Model for a NPN Transistor“. However, there are lots of unknown values that we need to determine to build a model for the actual transistor we are going to

Continue reading Reading a Datasheet for our DC Transistor model parameters.

Circuit simulation software – Qucs

A Simple model in Qucs

I spent a fairly large about of time trying to find some simulation software to meet the needs of this blog and the readers of this blog. Some of the criteria I used in the search were:

Free or very low cost: Most of us do not have hundreds

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Thevenin and Norton equivalent sources.

Thevenin equivalent source.

Now that we have talked a little about ideal sources it is time to get real. Yeah, I really do mean that. We are going to talk a little about real sources and modelling those. The first one I am going to talk about is the Thevenin model shown in the

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Design, Models, and Simulations

Design, if you are lucky, is based upon some calculations developed from a model of the thing you are attempting to design and construct. Often, as we have seen with the sheet metal brake project you are not lucky and we are left “flying by the seat of our pants.” Other times we know the

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Introduction to Bipolar Junction Transistors – Part II

A testing biasing circuit for a PNP Transistor

Tonight’s post is a continuation of the previous post “Introduction to Bipolar Junction Transistors“. In that post I talked in detail about the current flow in an NPN transistor, this post will start out with the same detail about a PNP transistor. Later I will extend

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Making a hinge mortising fixture.

Router Guide Bushing

In computer programming there is a term called “stuck in an endless loop”. Usually programs do the same thing over and over using different numbers and if you somehow forget to tell the program how to stop executing the loop it just continuously keeps doing the loop forever. Sometimes us humans

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