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Need switching circuit

Discussion in 'Electronic Design' started by GoatBoy, Oct 2, 2005.

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  1. GoatBoy

    GoatBoy Guest

    I'm in need of a switching circuit for a project. The project will
    have 3 switches. When any one switch is pressed, it will deactivate
    the other 2 switches. This will be an audio project so I expect I may
    have to use relays which will be fine. Momentary switches are also OK.

    goatboy1GROOVINATgmail.com
     
  2. Mac

    Mac Guest

    You may think you have explained what you need, but you haven't.

    Please elaborate a little bit. For example, what do the switches do when
    they are not de-activated?

    Are you trying to build something like a Jeopardy trigger where the first
    person who presses the button gets to answer in the form of a question?

    --Mac
     
  3. Pooh Bear

    Pooh Bear Guest

    Sounds like he may simply want an equivalent of those interlocked pushbutton
    switches so commonly used as source selectors.

    Graham
     
  4. GoatBoy

    GoatBoy Guest

    This is for an audio circuit. When deactivated, the switches will
    simply bypass a section of the circuit. THe switches will be spaced
    several inches apart.
    Almost like the jeopardy trigger, except pushing a button activates
    that button and switches off the other 2. I'm thinking I may need to
    do it with relays and logic circuits.
     
  5. John Fields

    John Fields Guest

    ---
    You still haven't clearly defined what you want.

    I'm assuming you have three audio sources and you'd like to connect
    the source associated with the last switch activated to some device
    while preventing the other two sources from being connected.

    Is that correct?
     
  6. GoatBoy

    GoatBoy Guest

    This is an audio circuit using 3 footswitches. 2 switches activate or
    bypass circuitry in the signal path (section 1 and section 2). Again,
    when activated each switch will deactivate the other 2. The 3rd switch
    bypasses all the circuitry when activated and deactivates the other 2.
    Think of it as a straight audio path with input>section 1 >section 2
    I'll see if I can put a block diagram together today and post a link.
     
  7. You may quite possibly not need to do that. You need to tell us exactly
    what is being switched. For example, is one signal switched to any one
    of three points or are three signals to be switched to one point? Does
    one switch have priority over the others or do you want it so that any
    switch that is ON has to be set to OFF before another switch can be set
    ON?

    If you can do a simple ASCII art diagram here, or put a graphic on
    a.b.s.e., showing the basic switching without the interlock feature,
    that would help a great deal.
     
  8. Use a BASIC STAMP.

    --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     
  9. GoatBoy

    GoatBoy Guest

    Here's a diagram of the circuit:
    http://www.ronsound.com/ebay/circuit.jpg

    Anytime one of the switches is closed, the other 2 should open. I know
    it looks a bit redundant, but it's for a friend and that's how he wants
    it. He wants to just be able to hit a switch and go to that setting.
    To make it more difficult, each switch will have an LED that lights to
    indicate the active switch.
     
  10. GoatBoy

    GoatBoy Guest

    Here's a diagram of the circuit:
    http://www.ronsound.com/ebay/circuit.jpg

    Forgot to mention that in order to make more difficult, each switch has
    an LED to indicate active status.

    Here's the basic switching idea:

    Switch 1 open (LED on) causes Switch 2 to open and Switch 3 to close
    (LEDs off)
    Switch 2 closed (LED on) causes Switch 1 to close and Switch 3 to close
    (LEDs off)
    Switch 3 open (LED on) causes Switch 1 to close and Switch 2 to open
    (LEDs off)

    Switches 1 and 3 need to be double pole to completely disconnect the
    sections from the audio path. I guess Switch 2 could simply be a
    cancel switch, causing Switches 1 and 3 to close.
     
  11. GoatBoy

    GoatBoy Guest

    Here's a diagram of the circuit:
    http://www.ronsound.com/ebay/circuit.jpg

    Made a mistake in stating my needs.

    Switch 1 - open (LED on) equals switch 3 closed, switch 2 open (both
    LEDs off)
    Switch 2 - closed (LED on) equals switches 1 and 2 closed (both LEDs
    off)
    Switch 3 - open (LED on) equals switch 1 closed, switch 2 open (both
    LEDs off)

    I guess Switch 2 could be a cancellation switch that causes 1 and 3 to
    close. Switches 1 and 3 would need to be double pole switches to
    disconnect the sections entirely from the audio path when they are
    closed.

    This is a device for his guitar. When not in use (Switch 2 LED on),
    there will be a straight path thru the device for the signal with no
    other circuitry bleeding off tone.

    I think that's about as clear as mud.
     
  12. John Fields

    John Fields Guest

    ---
    It still doesn't make a lot of sense to me.

    Here's your sketch in ASCII. View it with a fixed pitch font like
    Courier:



    +-----------+ +-----------+
    IN>--+--| SECTION 1 |--+--| SECTION 2 |--+--->OUT
    | +-----------+ | +-----------+ |
    | ___ | ___ |
    +------O O--------+-------O O-------+
    | 1 ___ 3 |
    +----------------O O----------------+
    2

    You say that, "Anytime one of the switches is closed, the other 2
    should open."

    So, if 1 is closed, then 2 and 3 will be open and the audio will be
    routed around SECTION 1 and won't be allowed to get to OUT through
    2, but will have to go through section 2 on its way to the output.

    Similarly, if 3 is closed, 1 and 2 will open and the audio will have
    to go through SECTION 1 and then make its way to the output through
    3.

    Now, if 2 is closed, 1 and 3 will open and the audio input will be
    connected to OUT through 2 as well as being forced to travel through
    SECTION 1 and SECTION 2 and eventually connect to OUT as well.

    Is that what you really want? I don't think so, unless your friend
    wants a lot of feedback.

    Why don't you just come clean and tell us what he wants to do?

    Does he have a couple of [guitar] effects that he wants to engage
    with foot switches, like hit switch 1 and effect 1 comes out, hit
    switch 2 and effect 2 comes out and hit switch 3 and both effects
    (or neither) come through? Inquiring minds want to know!-)
     
  13. GoatBoy

    GoatBoy Guest

    "You say that, "Anytime one of the switches is closed, the other 2
    should open.""

    Yeah, I said that but I was wrong. Switches 1 and 3 are closed when
    switch 2 is closed. Been a long and busy weekend.


    "Does he have a couple of [guitar] effects that he wants to engage
    with foot switches, like hit switch 1 and effect 1 comes out, hit
    switch 2 and effect 2 comes out and hit switch 3 and both effects
    (or neither) come through? Inquiring minds want to know!-) "

    That's exactly it, but at no time should both effects be working.
    Switch 3 (switch 2 in the diagram) would simply be a bypass switch for
    the entire device. Once either effect switch is engaged the bypass
    switch would open.

    I haven't meant to be so vague. You just put it in better words than I
    did. For that, I thank you.
     
  14. John Fields

    John Fields Guest

     
  15.  
  16. GoatBoy

    GoatBoy Guest

    John,
    You had it right. I need 2 switches, one for each effect. Engaging
    one effect turns the other off. There is also a 3rd switch, a bypass
    switch which turns both effects off but can be cancelled by engaging
    one of the effect switches. Each switch has an LED to indicate active
    status.
    I'm really sorry if I'm making this difficult. I'm trying to put it
    as plain as I can with all the pertinent info. I realize that in my
    initial post I got my info wrong. I posted it as a last minute thing
    before I went to bed so that's my bad.
     
  17. John Fields

    John Fields Guest

    ---
    OK.

    So, if switch 1 was engaged, the output of effect 1 would go to the
    amp, if switch 2 was engaged, the output of effect 2 would go to the
    amp, and if neither switch was engaged the guitar's unmodifed output
    would go to the amp.

    Additionally, you want a lit LED to reflect that effect 1 is active,
    another mutually exclusive LED to reflect that effect 2 is active,
    and if neither LED is lit you want that to indicate that there's a
    straight-through connection between the guitar's output and the amp

    Right?
     

  18. + ---------.--------------.--------------.
    | | |
    [RELAY1] [RELAY2] [RELAY3]
    | | |
    o-------. o-------. o-------.
    | | | | | |
    [N.C.2] | [N.C.3] | [N.C.1] |
    | | | | | |
    [N.C.3] | [N.C.1] | [N.C.2] |
    | [PUSHB1] | [PUSHB2] | [PUSHB3]
    [N.O.1] | [N.O.2] | [N.O.3] |
    | | | | | |
    | | | | | |
    - ---------'-------'------'-------'------'-------'

    You can put the leds (with a resistor) parallel to the relay coils.
    Also put a diode parallel to the relay coils, anode to plus side.
    The pushbuttons should only make contact as long as you keep them
    pressed, like doorbell buttons. "N.C." are normally closed contacts,
    and "N.O." are normally open contacts.

    I have not drawn the audio path, but hopefully you can figure
    that out yourself.
     
  19. GoatBoy

    GoatBoy Guest

    You got it, John. THat's exactly it.
     
  20. ehsjr

    ehsjr Guest

    Here's my version of what I think he wants:
    2 flip flops. Switch 1 engages ff1; switch 2 engages ff2;
    switch 3 resets both ffs; ff1 on resets ff2; ff2 on resets ff1
    The on state of a ff is used to drive an LED and to gate
    some speciffic effect to some specific place


    I won't invest any time drawing it, as I'm not sure I
    understand him.

    Ed
     
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