REPLACING OF LATCHING SWITCHES

Discussion in 'Digital Circuit Design' started by Nanda Kumar 1, Aug 25, 2016.

  1. Nanda Kumar 1

    Thread Starter Member

    Aug 25, 2016
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    Hi every one .Is there any electronic circuit to replace the latching switches(push to /push to off)?
     
  2. crutschow

    Expert

    Mar 14, 2008
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    Yes.
    What do you want to control with the push on / push off?
    What power is available?
     
  3. Nanda Kumar 1

    Thread Starter Member

    Aug 25, 2016
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    just i want to control one LED. 5v power is available.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    Do you need it to come up in any particular state when the power is first applied?
     
  5. Nanda Kumar 1

    Thread Starter Member

    Aug 25, 2016
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    Thank you for u r reply @crustschow.
    My requirement is when i press the push button(Tack tile ) led will ON.And if press once again Led will be in OFF state.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    Below is the LTspice simulation of an alternate action circuit which uses a CD4013 CMOS FF that changes state every time the push-button is pressed to alternately light the LED D1.

    upload_2016-8-25_12-19-44.png
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Why not use a maintained P.B.?
    Push on- Push off?
    You can also do it with a relay circuit flip-flop using a momentary P.B..
    Max.
     
  8. Nanda Kumar 1

    Thread Starter Member

    Aug 25, 2016
    37
    0
    Thank you Crustschow.Circuit is working fine ,I checked with simulation. If i want to contol 7 leds with different 7 tactile switches ? For these i want to use single ic or 7 number of CD4013?
     
  9. Nanda Kumar 1

    Thread Starter Member

    Aug 25, 2016
    37
    0
    Hi MaxHeadRoom , thank you for u r reply . Presently iam using same (maintained P.B). I want to eliminate using of maintained P.B ,because some time mechanical switch will give problem. so i thought use simple tactile switch with latch circuit.
     
  10. Kjeldgaard

    Member

    Apr 7, 2016
    71
    16
    If the D flip / flop circuit to be realized, then it may be easiest to use a MOS 4013 with Schmitt Trigger Clock Input, such as NXP HEF4013.
    Then it requires only a pull down resistor and a R/C filter to get a safe switching the output.
     
  11. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    The circuit you are after is called a toggle or T flipflop. Most general purpose J-K or D flipflop chips can be configured to do this. You also can do it with a hex inverter or any other inverting logic gate like a quad NAND or quad NOR chip. Search for 'toggle flip flop circuit' and you will get many schematics. Here is a 2-transistor circuit I lifted from somewhere in the past. Replace the LOAD resistor with a resistor and LED. You can delete the RESET switch.

    Transistors = 2N7000 or 2N7002
    No need for 1% tolerance resistors. 5% or 10% will work fine.

    ak
    Toggle-1-c.gif
     
    absf likes this.
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Not if you use an industrial version, Telemecanique etc, and also if you wish to reduce any load on the switch contacts, a small simple relay would do it.
    Or use the single switch to operate a Mosfet direct.
    Max.
     
    Nanda Kumar 1 likes this.
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