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Closing a Curcuit when plugging in TRS?
Old 15th April 2018
  #1
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Thread Starter
Closing a Curcuit when plugging in TRS?

Hey, i am building an audio Adapter with multiple inputs right now. The specifics dont matter. I want the curcuit to close whenever an In- and an output are connected and only between these two. So for example i have 4 In- and outputs and i plug in a TRS on one side and idk a Tiny Telephone on the otherside, i dont want the signal to be split to every output, only to the one connected output. How do I do that? Or how is that done in things like Patchbays?
Old 16th April 2018
  #2
Lives for gear
There are lots of switching TRS jacks, from basic normal to ones that have extra switch contacts isolated from the plug. But I'm not sure from your explanation what you're trying to do... or even what you mean by "idk a Tiny Telephone" on one side. Are all of the TRS 1/4"? Or TT? Or mini? Is the signal normally distributed to multiple outs, but should stop distributing when something is plugged in? That's a basic normal. What about if two things are plugged in? Or do you want to be able to plug freely into any output, and have the same switching occur?
Could you draw a sketch and upload it?
Old 16th April 2018
  #3
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Thread Starter
I think it is as you said a basic normal. Its supposed to be an adapter, one Channel so only one Signal either Mono or Stereo goes into it and it should only go out of the Out where something is plugged in. So no splitting occurs and there is no loss. How is that done with lets say XLR or even cinch. I have got a basic idea how it is with TT and 1/4" but you probably know more than i do.

I cannot upload a pic in here but i could PM it to you if u need it.
Old 16th April 2018
  #4
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There is no way to do what you want without building in selector switches - one for source, and one for destination - however, there is no signal degradation incurred - no splitting and no loss - by allowing the signal to simply be present at the other jacks as long as you've built your circuit in a shielded - preferably steel - box, and do your best to keep your pairs twisted internally.
Old 16th April 2018
  #5
Lives for gear
Everything Ripple says is true. I don't know if that solves your problem; I'm still not sure what you're trying to accomplish.

You want an adapter that doesn't load the source circuit when nothing is plugged in? That's inherent: an open XLR, or TRS, or Cinch or DB or any other plug doesn't "leak" signal if it's not connected to anything.
Or are you trying to provide a constant impedance to the source, which applies a loading resistor but then takes it away when you plug in? That's a basic normal.
Or are you trying to distribute a signal to multiple inputs, but not have any of the others change when you connect or disconnect one input? That's either a matter of planning appropriate bridging, or using a DA.
Old 17th April 2018
  #6
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Thread Starter
Do i need to have a selector switch for Inputs? Or is it enough for me to have a switch for selecting the output?
Jay how do i build a basic normal? Have you got a website or something where i can look how to build that?
Old 17th April 2018
  #7
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If you truly need a one-to-one configuration, then yes, you'll need both switches. If you need a one-to-many, then you want the input/source switch. If you need a many-to-one, then you want the destination/output switch. But, you can make a many-to-many without using switches at all. This assumes that your box is dedicated to performing it's function with only one signal. If you need it to perform it's function with more than one signal, then using an inexpensive patchbay between the inputs and outputs in order to assign your signals is probably the least expensive way to accomplish this. Additionally, making a "Mult" section on the bay will allow you to assign a single input to multiple outputs as well. Multiple inputs to a single output is not advised - a mixer or resistor network is required to perform this function properly - something you could build into the patchbay as well. Do a quick google image search for "patchbay normalling".
Old 17th April 2018
  #8
Lives for gear
Wondertrader, information on normals is all over the web. It's also in my books, and IIRC there's something about it in the tutorials section of my website. Click on "my recordings/credits" on the left, then use the right hand navigation panel at my studio page to go to the top of the site.

If you just want to figure it out from a drawing, here's Switchcraft's. I can't tell if that's the configuration you need (1/4"? TT? Mini?) but shows how they're built.
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