simple question possible simple answer

Discussion in 'General Electronics Chat' started by saint_jay77, Oct 19, 2006.

  1. saint_jay77

    Thread Starter Member

    Oct 19, 2006
    26
    0
    Hi,
    I am a new electrical engineering student and am a newbee at the practical stuff. My friend is restoring a classic Italia model car. He wanted me to help him design a switch for him. The switch shhould have the following spec:
    Press the momentary push button--> should turn ON the light or any component in the car with max current of 15 amps.
    Press the momentary push button again --> should turn off the component.
    He said he wanted to use a FET or an IC.
    Is there a circuit such as this?? Is it better to use IC , a FET or a combination. Would this circuit be called a flip flop!!! I would think that 2 NAND gates would do the trick set as a flip flop. The flip flop driving the gate of the FET or TIP transistor. Wondering if a lot of people can shed some light on this issue and help me think in different perpectives giving me an idea as to what to do.. any info will be helpful...
     
  2. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    2 NAND gates could be wired as an S R flip flop, but that would require 2 buttons, one to switch ON (SET) and one to switch off (RESET).
    You can however wire up a JK flip flop or D flip flop as a Toggle http://www.allaboutcircuits.com/vol_4/chpt_10/6.html/j_k_flip_flops, and use the output to drive a MOSFET which should do what you want.
     
  3. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    You'd probably need a debounce circuit as well.
     
  4. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
  5. JohnnyD

    Well-Known Member

    Aug 29, 2006
    79
    0
    hi i've made exactly this thing for my car. it only switches a few mA at the moment but can very easily be made to switch a relay. I'm only a beginner though so somebody might see lots of errors. I'd appreciate any suggestions for improvement.

    [​IMG]

    ignore the labeling of the inputs and outputs. just add a relay driver to either output of the 4013.
     
  6. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    Like... Use a low drop regulator if you want it to actually do its job ? ;)
     
  7. JohnnyD

    Well-Known Member

    Aug 29, 2006
    79
    0
    hi, could you expand a little further? I don't understand what you just said.

    The voltage regulator i used when i built this circuit for myself was a 100mA one, not the 1A one in the schematic (the program i use to make schematics only has the 1A version).
     
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