Resistors

• Resistors in series:

  RT = R1 + R2 etc...

  Resistors in parallel:

  1 / RT = 1/R1 + 1/R2 etc...
• When selecting an appropriate resistor:

  • Find the closest value to the required resistor in the series
  • Choose the next size up to ensure the component is adequately protected.
• A pre set potentiometer has a resistance control that is adjusted (normally with a screwdriver) and then fixed.  These resistors are normally only adjusted once.
• Remember pull up / down resistors also are needed, but this was learnt in electronics.