Resistor Placement and Confusion Regarding PrattSchematics

Discussion in 'General Electronics Chat' started by kprime, Feb 10, 2015.

  1. kprime

    Thread Starter New Member

    Feb 10, 2015
    I'm following along in Platt's Make: Electronics and I can't understand something very basic:

    "The triangle inside the diode always points from positive to negative."


    In the illustrated example prior to this, the resistor is attached to the black wire from the battery pack, which I thought was negative. Therefore, I thought the resistor went between the negative ground wire and the LED. Now he says it attaches to positive.

    I'm very confused. Do resistors go between the LED and the ground wire or not?

    Also, does it matter which direction they're facing?
  2. kprime

    Thread Starter New Member

    Feb 10, 2015
    My colossally useless fingers decided to hit "post" before I could edit the title. Apologies to Platt. I cannot figure out how to change it.
  3. Retiredguy


    Feb 24, 2007
    It does not matter which side of them LED ( light emitting diode) that the resistor is on in the circuit. The only reason it is there is to limit the current which flows thru the LED and the resistor can limit the current on either side of the LED provided that it is a series circuit.
    Lundwall_Paul and kprime like this.
  4. kprime

    Thread Starter New Member

    Feb 10, 2015
    Thank you!
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
    But conventional (not electron) current does flow in the direction implied by the LED arrow.

    The snap-connectors that attach to 9V batteries have the red wire connected to battery + and blk wire connected to battery -