Series of posts revising electronics DC theory
Y to Δ (T to π) Network Conversion Before reading this page I strongly suggest that you have first read and understood the complementary page on Δ to Y Network Conversion. The working out on this page is based on the results of that page. Previously we looked at how to calculate the values for […]
Voltage Sources What is a voltage source? This may seem like a redundant question. After all, we know intuitively from our modern lives that voltage sources are plentiful and come in a variety of different forms… and they do. For example: All of the above are indeed sources of electricity, and hence voltage sources. However, […]
Thevenin’s Theorem We have already looked at what a voltage source is in a previous article on Voltage and Current Sources. Thevenin’s theorem builds on that knowledge stating that: Any linear electrical network containing only voltage sources, current sources and resistances can be replaced at terminals A–B by an equivalent combination of a voltage source Vth in series with a resistance Rth. As a reminder. Here is a schematic […]
Norton’s Theorem We have already looked at what a current source is in a previous article on Voltage and Current Sources. Norton’s theorem builds on that knowledge stating that: Any linear electrical network containing only voltage sources, current sources and resistances can be replaced at terminals A–B by an equivalent combination of a current source IN in parallel with a resistance RN. As a reminder here is a schematic for […]
Millman’s Theorem Millman’s theorem says that: when a circuit contains a parallel connected network of practical voltage sources (they MUST have a series internal resistance), they can be replaced by a single equivalent voltage source with a series resistance. This theorem is not so much about performing circuit analysis directly, as it is about simplifying […]
Superposition Theorem The Superposition theorem is a basic circuit analysis technique that is only useful where there are more than one voltage or current sources in the same circuit. It states that: The current in any element is equal to the sum of currents through it produced by each source acting independently while the other […]
Mesh Current Analysis (a.k.a. Loop Analysis) The motivation for Mesh Analysis is that sometimes you have a circuit which is too complicated to solve using a simplification method, such as superposition. Mesh analysis on the other hand will work for any circuit that has just resistors and voltage and or current sources in any configuration. […]
Nodal Analysis The motivation for Nodal Analysis (a.k.a.the Branch Current Method) is that sometimes you have a circuit which is too complicated to solve using a simplification method, such as superposition. Nodal analysis on the other hand will work for any circuit that has just resistors and voltage and or current sources in any configuration. The […]
Capacitance What is Capacitance? Before I answer that question, let me start by clearing up something which has the potential to be very confusing… Capacitance has been given the designation C, which, as you will remember from the article on electricity, is also the symbol used for the unit of coulombs. I have no idea […]
Series & Parallel Capacitors Series Capacitors First of all consider what is happening. So we can say that: and from Kirchhoff’s Voltage Law we can also say that: and substituting for we get Then by dividing both sides by QTotal we get: If that last equation looks eerily familiar, it should. It’s the same equation […]