Switching problem

Discussion in 'The Projects Forum' started by jjj, Jan 13, 2009.

  1. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    I'm having yet another switching problem:
    I want to make footswitch, which turns on an effect. The problem is that, when the effect is switched on, it requires to activate the switch another time to turn the effect off.

    I want to eliminate the latter. That means, I want to press the pedal only for as long as the effect is needed and when I let the pedal go, the effect should turn off.

    That also means that the switching circuit needs to automatically activate the switch another time to turn the effect off.
    How can that be done?
     
    Last edited: Jan 13, 2009
  2. mik3

    Senior Member

    Feb 4, 2008
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    What is this effect?
    How it is controlled?
    Does it matter if you have the switch all the time pressed? Or the device will fail?
     
  3. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    It's a 244/245 KeyControl (via PC Kbd) for Live-Styler.de accompaniment (long story...)

    [​IMG] Click Image to Enlarge Image Hosting
     
    Last edited: Jan 14, 2009
  4. mik3

    Senior Member

    Feb 4, 2008
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    So if you push the switch the effect turns on and when you release it the spring pulls the switch back and the effect turns off, right? Isn't that you want?
     
  5. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    Yes... as you see on the mechanical switch. First I push the effect on and then, when I release the pedal, the switch contact goes briefly into "nothing" and then briefly touches the second contact and then ends up in nothing/off.
    Of course switching electronically will last longer.
     
    Last edited: Jan 14, 2009
  6. mik3

    Senior Member

    Feb 4, 2008
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    I got confused now!! Here you said you want it like that. What do you want to do?
     
  7. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    I want to eliminate the latter, means I don't want to press the pedal twice to switch off the effect.

    That means, I want to press the pedal only for as long as the effect is needed and when I let the pedal go, the effect should turn off.
    To clarify it I sent this mechanical switch... The exact action of this mechanical switch I want to create electronically.
     
  8. mik3

    Senior Member

    Feb 4, 2008
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    Ok connect the input voltage to the common of the switch, connect the normally open contact to the effect and then connect the normally closed contact to the normally open contact. With the switch you show it should turn off when you release the pedal.
     
  9. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    In switching terminology that is called momentary action, just like a spring loaded push button switch, press in and it turns on, release your finger and it turns off.

    Lefty
     
  10. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    Not quite, because to turn the effect off the switch has to be another time (briefly) activated.
    A momentary or pushbutton switch only switches momentarily on and off.

    The mechanical switch shows it very precisely.
     
  11. mik3

    Senior Member

    Feb 4, 2008
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    When you press the petal the switch touches the left contact (according to diagram) and when you release it touches the right contact momentary and then goes to the final position. The effect should turn off, however, maybe the switch moves to fast and the effect response time is not enough to detect this momentary touch. Find another switch with normally open and closed contacts, connect it as I told you in post #8 and it will work.
     
  12. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
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    The built-in sensing circuit latches the action of the petal into either of the two stable states. As it is now it requires one "press & release" operation to change into another state.

    What the OP wants is "something" between the petal and original connection that will send a pulse when the petal is depressed and send another pulse if it is released.
     
  13. tokoroatech

    New Member

    Jan 14, 2009
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    First of all, does the existing switch lock in one position and get released on the next press. If so, a simple spring-loaded on/off switch would do.

    Otherwise, the existing effect, whatever it is, has a push on/push off operation, as used in many modern appliances, which needs to be replaced with a push on/release off electronic switch.

    If this is the case your footswitch need to generate a pulse, of the same polarity, when turned either on or off (assuming the original switch is not a mechanical push on/push off switch).

    I'll get back to this later, I've run out of beer so it must be time for bed!

    Hope this helps to clarify what seems a confusing query on first reading.

    Cheers all,

    Tokoroatech
     
  14. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,577
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    It appears that he needs is an "edge detector". Not sure of the polarity, voltage, or timing in the pedal circuit, but the attached will provide a pulse on each press and each release.

    Ken
     
    Last edited: Jan 14, 2009
  15. jjj

    Thread Starter Senior Member

    Feb 25, 2007
    111
    0
    The way it looks, maybe I need to reveal "the whole, boring story" how I want to apply this switch/ switches.

    It's actually not a footpedal, but a knee lever control, which has to do with www.live-styler.de PC Key Control 244/245. Confusing and boring, I know! :)

    Now it allows me to switch the YamahaStyles accompaniment via 2 switches (from the PC-Keyboard) from major to minor or 7th chords.

    The trouble is that when I want to switch the accompaniment from major chord to minor or 7th chord, I need to press the PC switch another time to cancel the previously chosen minor or 7th chord, before I can switch back to a major or over to a 7th chord.

    I hate that, because there's no time for it; also it would be pretty confusing.
    That's why I want to only have to press the knee lever once for either minor or 7th and when I release (or don't touch) the lever, the lever stays invariably in (the center) major chord position.

    [​IMG] Click Image to Enlarge Image Hosting
    Operation: First I push the effect on and when I release the pedal, the switch contact goes briefly into "nothing" and then briefly touches the second contact (canceling the chord) and then ends up in nothing/off.
    Electronics switching will of course last longer.

    Today I wanted to open my cheapo-China PC-Kbd to see how to get the two skinny wires of its keys wired up. I'm worried that this will be almost impossible. Soldering not on? Any lateral ideas on that?
     
    Last edited: Jan 14, 2009
  16. mik3

    Senior Member

    Feb 4, 2008
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    Use a switch where the moving contact does not stop into nothing but stops on the second contact. Thus the switch will always touch one of the two positions except the time you push it. This is a SPDT switch which has normally open, normally closed and common contacts. Connect as in post #8 and it will work.
     
  17. jjj

    Thread Starter Senior Member

    Feb 25, 2007
    111
    0
    That would make the PC-Kbd Sw continuously on and off.
    Oh... Thx for kicking me to get me realized that my mechanical switch is wrongly drawn as well, because the PC-Kbd keys can only be momentarily switched!!
    That means: first, when I press the knee lever the PC-Kbd key has to be briefly activated (to turn on the effect) and when I release the knee lever, the same PC-Kbd key has to be briefly activated (to turn off the effect).
     
  18. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Ok just disconnect the left contact from the right contact and leave the wire going to the effect only on the right contact (according to the diagram).
     
  19. italo

    New Member

    Nov 20, 2005
    205
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    To do what you want you need a switch. turn it on it stay on. disable your timer and it should work.
     
  20. jjj

    Thread Starter Senior Member

    Feb 25, 2007
    111
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