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I am wiring a 6 channel camera switcher (http://www.brandmotion.com/360-vision/blind-spot/6-way-video-switcher-9002-6118.html)

And in addition to the automatic triggers (there are 6 trigger wires, when one receives 12v, it switches to that camera) I want to add a manual switch. I've looked and looked for a 7PST (I think thats the term) ideally in a push button format (7 individual buttons) but I cannot find anything.

So my question is either 1) do these switches exist? or 2) How can I wire 7 individual switches so that only 1 circuit/switch can be putting out 12v at a single point in time?

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  • \$\begingroup\$ I've seen rotary switches like that, but no interlocked pushbuttons that weren't already installed in some piece of equipment. You might try to scrounge some, or you might do some googling with that term and see what you find. \$\endgroup\$ – AaronD Jul 6 '17 at 1:21
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    \$\begingroup\$ What you want can also be done with momentary buttons and relays, and can have lights added to indicate where it is (because the buttons won't). It's basically the same concept converted from a mechanical interlock to an electrical circuit, but that might be more complexity than you want to tackle. \$\endgroup\$ – AaronD Jul 6 '17 at 1:25
  • \$\begingroup\$ how would the relays communicate to each other to only allow one "talking" at a time? I only see the need for relays if using momentary switches, but still doesn't address the need for only one active at a time \$\endgroup\$ – JBlake Jul 6 '17 at 1:34
  • \$\begingroup\$ It might take some creativity and maybe two stages of relays to make it work, but the idea is that each relay latches itself on while simultaneously blocking all of the others. For example, a button could force its own relay on regardless of anything else; otherwise each relay is held on via all buttons released AND its own contacts closed. Technically, this arrangement could end up with multiple relays latched on, but only if you release their buttons at the exact same time compared to the relays' switching speed. Mechanical interlocks are actually easier to get "stuck" like this. \$\endgroup\$ – AaronD Jul 6 '17 at 1:45
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    \$\begingroup\$ But like Michael says, your best bet is probably a microcontroller that you can hook up buttons and relays to, and let the software do the work. I know you said you're not good at them, but they're so mind-bogglingly useful that it's really a good idea to learn. For example, I started out designing an analog circuit to automatically reset a Pi as part of a custom battery backup, just to be sure it was on when I wanted to use it. After getting mildly frustrated with the one little sub-feature that just would not work, I switched to an 8-pin uC with internal clock. Worked beautifully! \$\endgroup\$ – AaronD Jul 6 '17 at 1:56
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You are wanting a push button selector switch that works like the old style car radio channel selector buttons. These are available as a series of push button switches that have an interlock mechanism such that when any one button is pressed it causes any previously set button to pop out. Finding the exact correct thing for your application could be a challenge though.

You may be better off designing a thing with a small micro controller that accepts the necessary switch selector input signals and in turn drives outputs to some electronic signal analogue mux/switches that manage the video signal routing. Then you can have the software control the behavior as needed and the switches can be very simple momentary push button tact buttons.

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  • \$\begingroup\$ "push button selector switch" sounds like the right term, but google isn't giving me anything. A micrcontroller would do the job, but it's a lot of added complexity and I have no experience with them \$\endgroup\$ – JBlake Jul 6 '17 at 1:39
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    \$\begingroup\$ @JBlake - selector switches with the pop-out buttons are becoming more and more rare. The mechanical nature of these and their size makes then rather expensive. The MCU solution that I described is the way it is done these days as it is way less expensive. Usually these days I only see the push button type selectors on products where they have been specially designed and are manufactured in the 100's of thousands to drive the cost way down. Take for example the speed selector on a typical low cost kitchen blender. \$\endgroup\$ – Michael Karas Jul 6 '17 at 1:46
  • \$\begingroup\$ Makes sense. Microcontroller could be the way to go and a fun way to learn something new. Noob question, but maybe there is a pre-programmed IC chip that serves as a SP7T switch? Basically whenever it receives a new 12v signal, it switches to that one and shuts off all the others. How would I go about finding it? \$\endgroup\$ – JBlake Jul 6 '17 at 1:58
  • \$\begingroup\$ There might be some chip that would do part of that......however there are one channel chips that can be laid down on the circuit board that can perform the proper selection based upon how the MCU controls the. BTW you are unlikely to be able to find any switching type chip that can survive having 12V put to its inputs. You will have to so a design of some sort that steps the 12V down to the 5V of 3.3V that a microcontroller or other chip can typically handle. \$\endgroup\$ – Michael Karas Jul 6 '17 at 2:05
  • \$\begingroup\$ Dang, I forgot about the voltages... hmm this seems like a lot of added complexity for such a simple feature, but I can't think of any other way to do it. \$\endgroup\$ – JBlake Jul 6 '17 at 2:22

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