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Toggle switch

Discussion in 'General Electronics Discussion' started by zenith, Nov 3, 2012.

  1. zenith

    zenith

    29
    1
    Nov 3, 2012
    Hi,
    I'm after some advice/help with a toggle switch, sounds simple doesn't it.

    What I'm looking for, is a switch that will turn on 3 arrays of 9 leds one at a time,
    so I can have 1, 2 or 3 arrays lit.

    However, the way the lights are set up, I need the center set to light alone, the 2 outer sets
    to light together and all 3 to light together.

    Is there a simple way to do this, with just one toggle switch? if so, how would I wire the
    switch? and what type of switch would I require?

    This is a 12v battery system, with a buck converter dropping the voltage to 4.5v.

    I have basic electric knowledge, but limited electronics, so any help advice would be useful.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,214
    2,695
    Jan 21, 2010
    You need a toggle switch with three "throws". Here is a SP3T toggle switch. There's plenty more of these.

    This and a few steering diodes will do the trick.
     
  3. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    A simple toggle switch, no...
    A simple toggle switch and some backend logic, sure...
    A Single Pole, - Triple Throw, toggle switch, sure... (no off position unless you increase the throw to quad)
    A rotary switch, possible...
    A multi-position slide switch possible...
     
  4. zenith

    zenith

    29
    1
    Nov 3, 2012
    Thank you both for your replies, I was pretty sure there wouldn't be a simple answer :eek:

    Thanks for the link, I will have to read up on steering diodes and see if I can find a circuit diagram that I can follow, I have the ability to build a circuit from a diagram, but not to design a circuit yet.

    I would prefer a toggle switch, I need to be able to use it with just my thumb, it will be mounted on a bikes handlebar.
    The off position I would presume could just be disconnecting the power supply, from the light unit.
    If either of you know of a diagram that I could use, or a site that could explain it in easy terms, I would be grateful.
     
  5. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Here is a quick schematic using a SP3T switch...

    Note the 'steering' diodes are the two located on the third switch position... The 'grey' steering diodes are 'optional' but if used they will maintain 'brightness' levels if the LEDs are balanced with resistors for a specific voltage... Or another way of saying it with the optional diodes all switch positions will have the same slight voltage drop resulting from the steering diodes, without the optional ones only the last position will experience this slightly less voltage... This might or might not effect LED brightness... For the two pennies it cost to get a few extra 1N00x diodes it's IMO best to include them just for consistency...

    [​IMG]
     

    Attached Files:

  6. zenith

    zenith

    29
    1
    Nov 3, 2012
    CocaCola, thank you for the diagram, now that I've seen the circuit it looks so easy and yet for some reason, I just couldn't get my head around it. :eek:

    As soon as I pickup the switch, I will get it all wired up.

    Just one more question if I may.
    The diodes drop 0.7v, so would I be right in thinking that I can increase the voltage out of the buck converter to compensate for that?
     
  7. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Yes, if the LEDs are balanced to the input voltage with resistors, and you use all the steering diodes I pictured you can assume the LEDs are now getting 0.7 volts less... You can increase the input slightly, lower the resistors slightly or simply leave it as is and it will still likely work...
     
  8. zenith

    zenith

    29
    1
    Nov 3, 2012
    Thank you for your help CocaCola, I am unable to build this circuit until I replace my soldering iron, since it died half way through :( . at least I know how to spend my end of year bonus now :) on a decent soldering station.
     
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