Series of posts revising electronics DC theory
Charge and Volts To avoid a long excursion into fundamental physics and the history of it’s discovery we will accept on faith two fundamental facts: Before we go any further. Yes I am aware that this is not really how atoms look, but it is the classic model and it works for my purposes here. […]
Resistance Resistance, as it’s name suggests, is the property of resisting the flow of electricity. In our water analogy it is the cross sectional area of the pipe along with how smooth, straight and long the inside of the pipe is that restricts the flow. In the case of our free electrons flowing through the atoms of […]
Practical Resistors Materials Resistors can be made from a wide variety of materials. Here are some examples of the most common types produced, along with a brief description of how they are made. Wire Wound Typically made by winding a resistive wire (such as nickle-chromium alloy) in a spiral around an insulating core (such as […]
Power and Joules Law Intuitively we all know what power is. A more powerful motor can turn a heavier load, or turn it faster; A more powerful torch will shine brighter; A more powerful heater will heat a larger volume faster. What these scenarios all have in common is to show that more power equates […]
Maximum Power Transfer Theorem This one of the simplest theorems that there are. It simply states that: Maximum power will be transferred when the internal source resistance is equal to the load resistance. This sounds counter intuitive to most people so some proof is often useful. However, the full proof requires the use of calculus […]
Series Resistor Circuits Making further use of our analogy with water circuits. Resistors are like pipes and when you connect pipes together in series (end to end) they provide only a single path for the water. Hence they all carry exactly the same volume of flow. Thinner (higher resistance) pipes may have a higher pressure […]
The good news is that this law is just a very simple concept with no complicated equations to remember. Even if you never heard of Kirchhoff, you probably already know this law intuitively. I tried really hard to think of a suitable analogy with water, but I came up short. Instead I will use the […]
Parallel Resistor Circuits Parallel resistance is when two, or more, resistors are each directly connected between the same two nodes of a circuit. We can revert back to our default of using water analogies for this one. Consider a pipe that branches in to two or more pipes before finally re-merging back in to a […]
Like Kirchhoff’s Voltage Law (KVL), Kirchhoff’s Current Law (KCL) is also just a simple concept (arguably even simpler than the KVL). It simply states that: The sum of the currents in to a node are equal to the sum of the current going out of a node. Alternatively represented as: The algebraic sum of currents […]
Δ to Y (π to T) Network Conversion Many circuits contain sub-circuits comprising of a three terminal network connected in one of two ways: The Δ (or π) and Y (or T) networks can be configured to be electrically identical to each other. However, depending upon context one may be simpler to analyse than the […]