Turn power on and off using a Tactile button only?

Discussion in 'General Electronics Chat' started by Fuji, Nov 12, 2014.

  1. Fuji

    Thread Starter Member

    Nov 8, 2014
    100
    1
    Is there a simple circuit to allow a tactile button to turn on and off power in a circuit instead of using a relay or old toggle switches?
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    Yes. They're called a latch circuit, sometimes a flip-flop, toggle or bistable. There are many ways to build them and which you choose will depend on the load voltage and current and on how you prioritize the factors such as cost, size, component count, etc.
     
    Fuji likes this.
  3. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    You could use NE555.
     
    Fuji likes this.
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Turn on and off what circuit?

    I did this when I needed a simple low (zero was the goal) power way to turn on and off a battery powered device. I used a low dropout regulator that had an enable pin. The tact switch would enable the LDO then the circuit would hold that pin on while it did its thing.

    It was most helpful here that the circuit was microcontroller controlled, but I don't think that is essential.
     
    Fuji likes this.
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    I have some very small mechanically-latching on-off push switches that have a red flag to indicate on. They are ideal for battery powered equipment because they take no power in the off state. I don't remember where I got them....

    Allelectronics seems to have plenty to choose from...
     
    Last edited: Nov 13, 2014
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    tactile switches are used mosltly as on off switches in microprocessor operated devices like mobile radios from icom, yeasu and such. the work as an input to the processor to start up the radio with a relay. those radios pull current all the time to keep the processor running. any kind of latch ic would have to be pulling power to recognise the switch was pushed.
     
    Fuji likes this.
  7. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Last edited: Nov 13, 2014
    Fuji likes this.
  8. wayneh

    Expert

    Sep 9, 2010
    12,094
    3,033
    I recently fixed an appliance (a wine chiller) that uses capacitance switches under a glass control panel. No moving parts. The part I though was cool was that the switches (sensors?) were mounted on the PCB but had springs to hold them firmly against the glass. Nice solution that eliminates trying to fit them by positioning the PCB relative to the glass. Using the springs allowed a sloppy fit without ruining the function of the switches.
     
  9. Fuji

    Thread Starter Member

    Nov 8, 2014
    100
    1
    Thanks for the schematic. Looks pretty simple. I looked up Logic gates for toggle buttons, this seems more efficient when using NAND logic gates.
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    The concept is not just a toggle switch function, but also a power switch. Logic toggle functions need to be continuous powered...unless you've found a link to one that doesn't. ?

    Ken
     
  11. Fuji

    Thread Starter Member

    Nov 8, 2014
    100
    1
    Thanks for the reply!

    Are you speaking similar to SR Logic gate? That one looks like it needs to be continuously powered.

    There is a few latching toggle switch schematics I found here using logic gates, i might have to use fets or mosfets with it. A bistable logic needs continuous power as well?

    http://www.mosaic-industries.com/em...n-switch-turn-on/latching-toggle-power-switch
     
    Last edited: Nov 14, 2014
  12. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Interesting find!

    Ken
     
Loading...