Stopping circuit with switch.

Discussion in 'The Projects Forum' started by z00ze, Feb 21, 2012.

  1. z00ze

    Thread Starter New Member

    Feb 21, 2012
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    y0,

    I have little problem, and that is that I don't have any education about electronics, so I am complete noob/newbie/idiot. So sorry about that ;) Only thing I can do is to weld/solder pretty good :)

    I want to have system which main purpose is to stop circuit when switch has been pressed...

    Look at the picture I uploaded, here is my explanation.

    When Switch A connects it stops B circuit. For some time, between 50ms and 100ms.
    If Switch A keep pressed down, it won't stop B circuit totally, just first time switch A is pressed.
    The time must be adjustable from the rotating switch C.
    If main power from D has been disabled from the switch, it must have allow B circuit to connect.

    How to do it, what components I need, wiring diagram? Help? :(
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    488
    Just to get this right:

    1. When the switch connected to D is open, B is closed. Pressing switch A does do nothing then.

    2. When the switch connected to D is closed pressing switch A will interrupt B for about 50 to 100ms, but only the first time A is activated. Activating switch A again will do nothing.

    3. A is a momentary push button.

    Can you confirm these 3 assumptions?

    What is voltage/current for B?
    What voltage is D?
     
  3. z00ze

    Thread Starter New Member

    Feb 21, 2012
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    Sorry, forgot to tell the volts :) Also I'm not so good at english so I assume when you are speaking about "closed" the switch is "ON" and transfers energy and "open" means it doesn't transfer.

    1. Correct.

    2. Correct, expect keeping down switch A will not keep B open all the time. It will only make B open for that 50-100ms. But if the switch A is released and pressed again, it will work like before, making the B open for 50-100ms.

    3. Actually the switch what I am using is "PULL". So when I pull from the switch's rod, it will connect. But yes it is momentary, but it will keep connecting for like 1second so on first time it connects it opens B for 50-100ms. Even if A is longer connected than that 50-100ms.

    B is 4.7 Volts.
    D is 12 Volts.

    Hope you understand what I mean, also thanks for quick reply! :)
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    This can be done with a 555 monostable. I will draw something up later , if nobody else does.

    What's the current for B? Depending on the current you may or may not need a transistor.

    Is B galvanically isolated from D or can they have the same reference, i.e. Ground?
     
  5. z00ze

    Thread Starter New Member

    Feb 21, 2012
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    D is battery, 4Ah 12V. But I don't know exact current for B, my meter doesn't read it... I only know volts for (exact volts is 4.36V) but lets assume amperes are same as on battery?

    D and B are totally different systems. B gets power from D but through other switches/relays/boxes and so on. So let's say they are isolated from each others... B acts just as signal to other system.
     
  6. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    You still didn't say how much current is needed for B.

    This is necessary to determine the switching device.

    Note that in the following circuit "K" is not a normal relay but a solid state relay or optorelay. These contain MOSFETs that switch the load. They are available as normally closed versions.
    It depends on your load if you can use a normal relay or not. If you connect a normal relay , then you will need a flyback diode on it. Also, you have to make sure not to exceed the maximum output current of the 555.

    [​IMG]
    Have a look here for relays apply the necessary filters: http://search.digikey.com/us/en/cat/relays/solid-state/1048664
     
  7. z00ze

    Thread Starter New Member

    Feb 21, 2012
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    I tested my meter and looks like it is broken, I'll get new meter and try to get right current.
     
  8. z00ze

    Thread Starter New Member

    Feb 21, 2012
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    Will take day or two until I get new meter...
     
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