Make: Electronics - Figure 2-35

Discussion in 'Homework Help' started by Sternschnupper, Jun 1, 2013.

  1. Sternschnupper

    Thread Starter New Member

    Jun 1, 2013
    2
    0
    I recently bought Charles Platt's Make: Electronics (first edition) as my first introduction to electronics. I have no prior experience whatsoever.

    Under Introducing Schematics on page 50 is a schematic (Figure 2-35) of a two-switch circuit. The positive end of the 3V power source leads to a 220Ω resistor, then an LED, the two SPDT switches then ending in the negative pole. When I built this according to the schematic, it didn't work. Only after reversing the poles (negative/black wire leading to resistor) as illustrated in picture form in Figure 2-17 did the LED illuminate.

    I would like to know if Figure 2-35 is simply misprinted or if there is some conventional flow/electron flow distinction I'm missing.

    If I'm posting this in the wrong forum, I'd appreciate advice on where to go. Otherwise, thanks in advance for your response.
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,960
    1,097
    I don't see any diagram? You need to add a circuit diagram.
     
  3. screen1988

    Member

    Mar 7, 2013
    310
    3
    Here are the circuits:
    [​IMG]
    [​IMG]
    I believe that these circuits are right. You need to reconsider your LED poles connection.
     
    Sternschnupper likes this.
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,960
    1,097
    Yes, the circuit diagrams are OK.
    All you need to do is double check how you connect the LED.

    [​IMG]
     
    Sternschnupper likes this.
  5. Sternschnupper

    Thread Starter New Member

    Jun 1, 2013
    2
    0
    Jony130 - I've attached the page with the schematic, though I just saw screen1988 posted a much better view.

    screen1988 - I've noticed on Figure 2-17 of your image that the blue and red wires are reversed compared to 2-17 in my book. Here's what I think has happened:

    screen1988's images are from a more recent edition in which the publisher has changed Figure 2-17 so that it matches the schematic in Figure 2-35. In my first-edition copy, Figure 2-17 has reversed the polarity leads AND the a-k direction of the LED. My confusion - and I should have seen this myself, but I'm dumb and new - came from assuming the two figures were identical set-ups, and I ignored the reversal of the LED leads. I hope this makes sense.

    Thanks to both of you for responding, and sorry for wasting your time. I'm looking for a forum where posting legitimate and dumb beginner questions is accepted, as I really am starting from zero here.

    Cheers
     
  6. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,960
    1,097
    So this forum will suit you well.
     
    Sternschnupper likes this.
  7. sheldons

    Active Member

    Oct 26, 2011
    616
    101
    obviously the low voltage led version of 2way switching-something i come across regularly only the 240v ac version .
    The last one was where someone had changed a light fitting and got the switch wire in the wrong place and dropped a neutral( behind the light fitting not in the ceiling rose) with the result that lights in other rooms didnt work and there was tripping breakers on operation of the light switch....
     
Loading...