help wiring of dc power jack and spst

Discussion in 'General Electronics Chat' started by endaya_walatch, Aug 8, 2011.

  1. endaya_walatch

    Thread Starter Member

    Sep 13, 2009
    33
    0
    Hi To all,

    I need some advice in wiring the dc power jack.
    What does the terminal A,B and C responds to?
    Honestly, I don't know the positive terminal and ground in this one.
    Please help me.
    =(

    Also for the switch.
    I'm a noobie here.
    Please help.

    Thank you in advance.
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    Here's an example datasheet of a similar DC coaxial power jack. As you can see, the terminals are numbered. Terminals 1 & 2 are always used. Terminal 3 is an optional connection to another power source such as internal batteries which are disconnected when the plug is inserted.
    http://products.cui.com/CUI_PJ-035C_Datasheet.pdf?fileID=4311

    Which terminal is used for power and ground varies depending on the product design but most use a center positive arrangement (terminal 1 positive, terminal 2 negative).

    The switch is a single pole single throw (SPST) switch. It's on or off. Look at the datasheet:
    http://www.carlingtech.com/pdf/CarlingSW_F.pdf. What's not to understand?
     
    Last edited: Aug 8, 2011
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    You need the datasheet for the jack to be sure. Whats the part number/manufacturer?

    A switch like that is basically just in/out. (Either those 2 terminals are connected or not depending on the switch position)
     
  4. endaya_walatch

    Thread Starter Member

    Sep 13, 2009
    33
    0
    Thank you very much for the reply.
    Now, I understand to use the dc power jack and switch.
     
  5. bogyman57

    New Member

    Sep 1, 2011
    7
    0

    I have a very similar question that I'm having a tough time getting advice on:

    I have a d/c powered (3-AAA cells) LED lamp with a proprietary spst switch that I would like to add a 2.1mm d/c power spst jack to. (the same one as previously mention in this thread).

    a.k.a. "dual power source"

    I want the original proprietary spst switch to control the power REGARDLESS of which power source is being used.

    I've been scribbling schematics for days and can't seem to come up with an answer on my own....

    Is there a way to do this without replacing the original switch?

    Thanks
     
    Last edited: Sep 1, 2011
  6. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    Using the socket shown here: http://products.cui.com/CUI_PJ-035C_Datasheet.pdf?fileID=4311

    Wire terminal 1 to one pole of the battery, wire terminal 3 to the other pole of the battery, and wire terminal 2 to the original switch.

    When the plug is not in the socket, the battery supplies the lamp. When the plug is inserted, terminal 3 disconnects from terminal 2 so the battery is cut out and the external supply is connected. Be sure to connect the external supply the same way around as the battery!
     
  7. bogyman57

    New Member

    Sep 1, 2011
    7
    0
    Thanks for the quick reply, but, I'm afraid it didn't work.

    The original switch turns on the leds when the batteries are installed (just like normal)

    But the unit is dead when I plug in the external power source.

    Pin.1 on the jack is negative, as is the wiring on the plug - center ground, sleeve hot, 4.5 vdc wallwart, putting out 6.84 vdc unloaded)

    Here's a drawing of my interpretation of your instructions:

    What have I done wrong?
     
    Last edited: Sep 2, 2011
  8. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    That looks correct. If the plug and jack aren't sized right, especially the center pin and it's corresponding socket on the plug body, the plug will fit snugly into the jack and the sleeve will connect correctly with pin 2 of the jack but the center pin will float in the socket on the plug body without making contact with pin 1 of the jack. This is an indication that the pin is too small or the socket is too big.
     
  9. bogyman57

    New Member

    Sep 1, 2011
    7
    0
    I found the problem.

    Apparently, pin 2 & 3 are reversed on the particular model of jack I'm using.

    I switched them around, and voila! It works like a charm!

    Thank you all for your help

    edit: OOPS, the 4.5 vdc 1500ma wallwart burned out all my leds... I should have beefed up the resistor while I was at it.
    I took it for granted that a 1/2 watt resistor could handle it...
    (live and learn)
     
    Last edited: Sep 2, 2011
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