Background: I'm working on a project that would allow a number of people to hook up their laptops to a single monitor through a KVM and use buttons on the desk to control who has control of the monitor. Originally, the plan was to use buttons with microcontrollers to send keyboard shortcuts to the KVM which would then switch to a given input based on what keyboard shortcut was sent. I've run into a problem because the keyboard switching is a little.. off. The only way to do it without installing software is to cycle through the inputs 1 by 1, and it's a requirement that the user not need to install anything. So now I'm wondering if its feasible to interact directly with the KVM hardware. Worst case scenario, we could just plant the KVMs on the table, but that's not quite as user-friendly.

Problem: I want to have a bunch of buttons on a table, ~6ft away from the KVM, which would replace the buttons on the KVM board. I'm not sure how to do this, but I have a few ideas (not sure if they're feasable):

  1. Remove the buttons and solder wires in their place, which would be connect to the buttons on the table.
  2. Connect the wires from the table buttons directly to the leads of the buttons on the board, without removing them.
  3. Some kind of tiny motor or something that could push the buttons on the KVM. (Rather avoid this)

So I guess the question is: which of these would be the easiest, and what's the best way to go about it? Also open to suggestions on entirely different solutions..

First picture is of the top of the KVM, where the buttons are soldered onto the board, the second is the underside of the board. The button connections can be seen sticking out of the board. Top of KVM board Bottom of KVM board

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    \$\begingroup\$ Is this supposed to be more clear? Instead of once KVM you write it twice. Is it so hard to say what it stands for? And don't ":s" and "/g" me. \$\endgroup\$ – stevenvh Jun 28 '12 at 19:22
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    \$\begingroup\$ KVM switch. Or just Google KVM \$\endgroup\$ – Mannimarco Jun 28 '12 at 19:26
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    \$\begingroup\$ Nowhere in your question you mention "KVM switch", you just talk about KVM. Don't expect everybody to know what you're talking about, we just happen to bump into a question, with zero context. BTW, if you google it your first two hits are about the Virtual Machine. Also, your well-mannered comment has been flagged. \$\endgroup\$ – stevenvh Jun 29 '12 at 4:59
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    \$\begingroup\$ @Mannimarco - If you want me to google KVM, why don't you google for an answer to your question? \$\endgroup\$ – stevenvh Jun 29 '12 at 5:11
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    \$\begingroup\$ C'mon guys, this is being overly pedantic, IMHO. The OP guy just wants to know if he can extend some buttons, it doesn't even matter what the device is. :| \$\endgroup\$ – dext0rb Jun 29 '12 at 13:57

You can simply solder long wires to the back of the board where the buttons connect and put buttons on the ends of the wires. If you get phantom switching (button presses when you weren't pressing a button) or several switches when you only press the button once then you'll have to look more carefully at the design of the circuit to eliminate false presses and properly debounce it.

But try long wires and buttons first - it should work fine.

The buttons you show have 4 pins. Connect your 2 wires to two diagonally opposite pins.

  • \$\begingroup\$ If using wires does not work a fall-back would be to use relays, placed near the buttons, switched by buttons via long wires. But thyat is probably not needed. \$\endgroup\$ – Wouter van Ooijen Jun 28 '12 at 18:24
  • \$\begingroup\$ @WoutervanOoijen Thanks for the edit, very good method to ensure you have the two contacts for this switch type! It seems like many of the movers and shakers on the piclist are here - glad to see you're here! \$\endgroup\$ – Adam Davis Jun 28 '12 at 19:15
  • \$\begingroup\$ Played around with it a bit, the pairs are on the left and right. Works great when I'm just messing with it with a couple spare pieces of wire, but will using longer wires (6-10 feet) cause any problems? Not really a hardware guy, so I don't know how much the current or voltage would degrade over that range (if at all). \$\endgroup\$ – Mannimarco Jun 28 '12 at 19:20
  • \$\begingroup\$ @Mannimarco It is very likely that those lead to high impedance inputs to the microcontroller that runs the KVM. Very little current will be running on the wires. The voltage drop will be very, very small due to the high impedance of the inputs, but even if the voltage drop is significant it will probably still work due to input level tolerances, which could allow a volt or more drop before having problems sensing the switch. Try it with long wires, then come back and describe any problems you encounter - chances are good that it'll simply work. \$\endgroup\$ – Adam Davis Jun 28 '12 at 19:24
  • \$\begingroup\$ Awesome, not sure what impedance is but I can just Google that. Thank you for the assistance, kind sir. \$\endgroup\$ – Mannimarco Jun 28 '12 at 19:28

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