LEDs IN SERIES PARALLEL
LEDs IN SERIES LEDs can be placed in series providing some features are taken into account. The main item to include is a current-limiting resistor. A LED and resistor is called a string. A string can have 1, 2, 3 or more LEDs. Three things must be observed: 1. MAXIMUM CURRENT through each string = 25mA. 2. The CHARACTERISTIC VOLTAGE-DROP must be known so the correct number of LEDs are used in any string. 3. A DROPPER RESISTOR must be included for each string. The following diagrams show examples of 1-string, 2-strings and 3-strings: LEDs IN PARALLEL LEDs CANNOT be placed in parallel - until you read this: LEDs "generate" or "possess" or "create" a voltage across them called the CHARACTERISTIC VOLTAGE-DROP (when they are correctly placed in a circuit). This voltage is generated by the type of crystal and is different for each colour as well as the "quality" of the LED (such as high-bright, ultra high-bright etc). This characteris...