A sick mind can ask this thing

[GreyIce]

Hello, some time ago i was thinking if it's possible to have 1 keyboard, custom for sure, that send in the same moment same command on 2 pc, with 2 cable. For some thing i need to make the same thing on 2 pc, and i think the only way, if it's possible to do that is with a custom keyboard with 2 controller maybe...

Is possible to construct a thing like this? 

[TalkingTree]

To my knowledge it's impossible because a device can only be accessed by one host at a time.

[GreyIce]

I was think if i solder all the switch on 2 controller, in the same time i will send signal on the both controller so i can have a double keyboard that word on 2 pc... 

[TalkingTree]

I was think if i solder all the switch on 2 controller, in the same time i will send signal on the both controller so i can have a double keyboard that word on 2 pc... 

Unless I'm missing something, in this scenario, when you're closing the contacts of the switch, you're electrically joining both controllers. That could lead to unpredicatable results, even severe damage to your device and computer.

[GreyIce]

Ok, so with the existing switches is not possible. So maybe i have to design a new switches to make this, i think with a double switch, with 2 separate electrical circuit is possible to not damage nothing, and the possibility to solder on 2 controller.

[Puddsy]

KVM switch?

[Snowdog993]

KVM switch?

I think what he is describing is more of a PS/2 "hub" with one input and multiple outputs?
My only question is WHY?

[TalkingTree]

Ok, so with the existing switches is not possible. So maybe i have to design a new switches to make this, i think with a double switch, with 2 separate electrical circuit is possible to not damage nothing, and the possibility to solder on 2 controller.

Designing a brand new switch for that is overengineering if you ask me.
You can perhaps use the same expedient depicted here.
Alternatively, you could use a different interface such as FireWire, which should allow you to do that, but you'll need at least a port on each computer and a dedicated firmware for your keyboard.
Neither sounds any simple.

[Tactile]

There are devices designed to do this. They're called keyboard broadcasters or sometimes multiplexers. There are people/businesses out there where they need to do this and no-one builds the capability into the keyboard, they buy these external boxes.

http://www.vetra.com/844Utext.html

[TalkingTree]

KVM switch?

Not a switch but a splitter.

There are devices designed to do this. They're called keyboard broadcasters or sometimes multiplexers. There are people/businesses out there where they need to do this and no-one builds the capability into the keyboard, they buy these external boxes.

http://www.vetra.com/844Utext.html

Yeah I didn't consider something complicated (and pricey) like this.

[GreyIce]

KVM switch?

I want to do that, send 1 button in the same moment. KVM is like a switch connected to 2 computer, and send signal just 1 computer at a time.


Now i look for the other answer and suggested thing, Thank you.

There are devices designed to do this. They're called keyboard broadcasters or sometimes multiplexers. There are people/businesses out there where they need to do this and no-one builds the capability into the keyboard, they buy these external boxes.

http://www.vetra.com/844Utext.html

Too expansive and i want to make it, is a question between me and keyboard...XD ) )

[_rubik]

This just sounds like an XY problem. What are you actually trying to solve? Why not just write a script to do one thing and run it in both places?

[Kevadu]

It's not a hardware solution but I believe there have been patches to Synergy to support broadcasting keystrokes to multiple machines simultaneously.  Not sure if that ever made it into the main branch but it should be possible at least.

[JianYang]

Yeah, it should be possible. The easiest would probably be to have the primary controller send the keystrokes to a secondary controller via UART. Similar to what happens with a let's split. In this case, the second controller would just also send the keystroke to the USB.

It would require a bit of custom firmware. But what possible application could this be?
In most cases, the simplest would probably be to write a desktop application (or perhaps you could find something) that just forwards all the keyboard input from the one PC to the other over ethernet.

[AMongoose]

Get two of those xmit hall effect keyboards. disassemble them and reassemble one of them with the second one's pcb jammed bellow the first one's pcb.
When the magnet of the switch lowers it activates the sensors for that key for both the pcbs!

Romer G switches have two contacts from what I know, you could also make a board with those.

[GreyIce]

Thanks for the answer. I prefer a hardware version of what i have in mind, and i think i found a solution.

By the way, cherry switch in what plastic are made? If someone know.

[ProtonDecay]

What did you end up going with? Post pics!

If you want to do it 100% in hardware using the tech stack of regular keyboards, you'd need to isolate the switch components from two identical keyboard circuits.

Really simply, you can think of it as two handwires/PCBs, each physically layered one on top of the other, with your choice of DPST switches (one circuit per layer), or using regular SPST keyboard switches with them all linked to the same +5v and acting on the V_in of two transistors (or relay(s)  ), providing a separate physical switch circuit for each physical layer.

[buckyballs]

Really don't understand what the heck is going on.

[GreyIce]

What did you end up going with? Post pics!

It ends i will made a new switch, a double switch. So i'll press one key on keyboard but i will have 2 separate output for 2 pc... I can post a picture but is mine invention that switch, so for now i don't know if i want to post in some place without register before the invention.



I still search, and if someone know

What plastic is used for the cherry switch?