Recently Viewed:
Home > ChapterOne
Chapter One
Basic circuit elements and Methods of showing voltage and current on a schematic Fig 1a shows the schematic symbols for the basic circuit elements. Fig 1b shows current and voltage arrows which show polarity. The head of the voltage arrow is positive and the tail is negative. The small current arrow shows the direction of current flow, assumed to flow from the positive to the negative. Fig 1c shows alternate forms of showing current and voltage. The first resistor has a small black arrow showing current direction. The second resistor has a ground terminal on the bottom of it, and the voltage at the top of the resistor is indicated with the letter 'V'. This is possible when the voltage is referenced to ground. The third resistor shows what the voltage from top to ground is, and shows what the current is and where this current is measured and what it's direction is. Although this seems simple, these are very important facts about circuit elements. In the future we'll always have to be very careful where we place our arrows and exactly how they are oriented. Ideal Circuit Elements and Real Life Circuit Elements Made Up Of A Combination Of Ideal Circuit Elements Voltage/Current Polarities First step in circuit analysis Kirchhoff's Current and Voltage Laws 4a&c: The sum of the voltages around a closed current path equals zero. 4b&d: The sum of the currents entering a node equals the sum of the currents leaving a node. How close an LED circuit is to a resistive circuit Replacing an LED with a voltage source Fig 6d is a simple parallel circuit. Parallel resistors in series with an LED THE FOLLOWING IS NOT PART OF THE COURSE (YET)
Series R Tester Circuit (below) This is just something to show what we will be looking at in the future. This circuit is more advanced then we want to deal with right now, but once we get going we'll find out how easy this circuit really is! This circuit can be used to measure the series resistance of an Liion cell. The 'ground' just to the left of R2 is removed for one reading and replaced for the second reading. When this action produces twice the current 'I' through R6 when the short is removed as when it is in place (as drawn) the resistor R2 is exactly twice the value of the series resistance. The Liion's series resistance is labeled R1 in this schematic. Powered by QwikiWiki 1.5.6  www.qwikiwiki.com
