Weight triggered, delayed, LED fade in.

Discussion in 'General Electronics Chat' started by Jesanicholls, Feb 11, 2015.

  1. Jesanicholls

    Thread Starter New Member

    Feb 11, 2015
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    Hey!

    I'm looking to turn on a strip of led lights (about 1' long). Here's the setup though... I want to turn them on via a weight triggered switch, a switch that when pushed would start a timer for 45 minutes, and once the 45 minute timer finishes, the LED's begin to fade in to full power over 2 minutes.

    Also, I would like to keep it as compact as possible.

    How can I do this?
     
  2. #12

    Expert

    Nov 30, 2010
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    This is the block diagram of how you do it. Now, do you have an hour or two to do the design work?
     
    Reloadron likes this.
  3. Reloadron

    Active Member

    Jan 15, 2015
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    There are weight triggered mats out there or actually pressure alarm system mats as a start if that is what you mean by "weight triggered". The 45 min delay on make is a long time but there are commercial timers that can do it. That would be a delay on make timer, a Google of "delay on make timer" will bring up dozens of hits. So we have the mat trigger the timer, we time out after 45 min and then fade in a LED string over 2 min. LED fade in and out circuits are pretty common. Afer all of this, then what as we are left with the LEDs lit? Rather than a mat that senses weight there are also IR prox sensors.

    Building the pressure sensor and DOM timer would be difficult, the timer only because of the time period involved.

    Another solution would be to use a micro controller and simply program it. This is likely the best approach and will keep things small and the parts count down. I am not a programmer type but we do have a forum section dedicated to micro controllers and programming them.

    Ron
     
  4. Reloadron

    Active Member

    Jan 15, 2015
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    Yeah, just that simple. :)

    I was busy typing while you got that out.

    Ron
     
  5. #12

    Expert

    Nov 30, 2010
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    It seems we all take turns stumbling over each other here. :p
     
  6. Jesanicholls

    Thread Starter New Member

    Feb 11, 2015
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    Thanks for the reply. I should clarify a few things...

    I'd like the weighted switch to be triggered by the weight of a full glass of water, and it cant rely on the wieght remaining on the switch. I need to be able to put down the glass on water on the switch, have the timer started, and be able to remove the glass and putting it back down without the circuit resetting. Is this possible?
     
  7. Jesanicholls

    Thread Starter New Member

    Feb 11, 2015
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    So... here is the exact scenario:

    A user puts a full glass of water on the trigger. The trigger starts the 45 minute timer. The user drinks the water (lifting the glass off and on the trigger which wont activate the weight trigger as the weight is reduced through the consumption of the water), and then after 45 minutes the led starts to fade in over 2 minutes. The user would then fill the glass of water and set it back on the trigger (the full glass now has the required weight to activate the trigger) which would turn off the LED and restart the cycle.
     
  8. #12

    Expert

    Nov 30, 2010
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    Add a latch and use a more sensitive switch.
     
  9. #12

    Expert

    Nov 30, 2010
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    And you changed the requirements again.
     
  10. Jesanicholls

    Thread Starter New Member

    Feb 11, 2015
    5
    0
    Sorry, I'm bad at this. Thanks for your help!
     
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