Using a momentary switch to switch signals.

Discussion in 'The Projects Forum' started by Forgetful Assistance, Aug 6, 2013.

  1. Forgetful Assistance

    Thread Starter New Member

    Aug 6, 2013
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    *First post so move if I have posted it in the wrong section please*

    Okay. I want to use a spst momentary switch to control a circuit that will switch two signals between one output 6.25mm jack. So I need it to act like a SPDT switch.

    I have done some searching and found this article:
    http://www.thetonegod.com/tech/switches/switches.html

    Pretty much exactly what I want but it acts like a DPDT switch rather than a SPDT switch. Thats okay but simply looking for options to reduce parts count.

    Any ideas? Thanks for the help in advance!
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Silly question, but why nor just use a SPDT switch?

    Parts count = one.
     
  3. Forgetful Assistance

    Thread Starter New Member

    Aug 6, 2013
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    0
    Yes that is the obvious solution but I'm going to over complicate it :rolleyes:

    If I was to use a mechanical switch I would need a DPDT because I would want an LED to indicate the status of the switch.

    The reason for using a momentary switch is noise. Not signal noise but noise that I could hear from the clicking of the switch. I am intending to use it for an audio signal so when I record myself in the studio I don't want to hear the "click" noise of the switch engaging when recording because the microphone will pick that up. The momentary will still make some noise but considerably less.

    I hope reason is logical to others as it is to me :D
     
  4. Forgetful Assistance

    Thread Starter New Member

    Aug 6, 2013
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    Just thought I'd add this incase I missed it. I don't expect someone to design a circuit for me. If you could point out an IC or two or a method that I can apply that would be much appreciated.
     
  5. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    Well, not knowing any better myself, you could use a CD4016 which is designed to switch signals. It has four SPST switches controlled electronically, so I think you could make a SPDT easily enough. What I don't know is how you intend to "quietly" send the control signal. Have you found a momentary switch that is quieter than a toggle switch?

    If you want to go for overkill, you could program a PICAXE and make a touch sensor from a piece of metal covered with a piece of tape and then control the CD4016 or a solid state relay or some MOSFETs.

    A simpler approach may be moving your existing mechanical switch under your desk/cabinet/microphone and covering it in padding. Perhaps put a shoebox with good padding over it and add a rod to push the switch.

    Just some ideas . . . :D
     
  6. Forgetful Assistance

    Thread Starter New Member

    Aug 6, 2013
    4
    0
    Using a Hex inverting Schmitt trigger and the CD4016/4066 was my initial idea. I was just looking to see if there were any other alternatives that would take less PCB space.

    Here's the schematic that I drew up. I've connected all the unused pins to ground. Thats the right thing to do, right? I'm new to this.

    [​IMG]

    I know this sounds very silly because a simple toggle switch would work :confused:. This inteded to be used for a guitar pedal:
    [​IMG]

    The switches typically used for guitar pedals are usually a little noisy and prone to failure. I assume that's due to the constant use with your feet. They can't be put a way because I need to be able to control them with my feet as I play guitar. I can add the guitar effects to the recording on the computer but I like to use "real" pedals rather than digital simulations.

    [​IMG]

    Thanks guys!
     
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