Making a KVM switch under 10$

[iamdarkyoshi]

Found this glorious hunk of crap at the thrift store:

 

And it was a staggering 4$. And what is inside?

 

A 30 pole double throw switch!!!! Thats INSANE!

 

What IO should I rewire it with? I am thinking two internal USB hubs (using USB hubs means I have only one port to switch), a DVI port, and maybe VGA?

 

I will keep this thread updated as I make progress.

[Electronics Wizardy]

Haven't tried this but you might have issues with interference due to the lack of sheilding and the switch not being designed for high frequencies.

Id try usb first.

[vanished]

Does it work?  That might explain why it was cheap

 

If it does, I definitely want to see how this goes

[VTF5252]

That is the one of the most simple products I've seen. Its very pleasing to the eyes. Especially the coloring of the wires.

[iamdarkyoshi]

2 minutes ago, Electronics Wizardy said:

Haven't tried this but you might have issues with interference due to the lack of sheilding and the switch not being designed for high frequencies.

Id try usb first.

When I rewire everything, I will use shielded cabling. I have probably 30 unopened DVI cables from monitors (used to work IT) so they will probably work fine. I will try running some signals through the o-scope and watch them dance, though my scope only goes up to 100mhz. Still should show any noise or signal crosstalk.

 

4 minutes ago, Ryan_Vickers said:

Does it work?  That might explain why it was cheap

 

If it does, I definitely want to see how this goes

I have nothing to test it with, I would imagine it does. If not, I have some contact cleaner. And brakleen.

[glitchmaster0001]

wait what are you going to use that hub for? 

[Mira Yurizaki]

DVI requires 17 pins minimum for a single link. 23 for dual link.

VGA requires 15 pins.

USB 2.0 requires 4 pins, USB 3.0 9 pins.

 

There are 25 pins on that guy.

 

So at best you could do a single link DVI and two USB 2.0 ports, if you did a direct attachment. Or VGA and USB 3.0

[iamdarkyoshi]

8 minutes ago, M.Yurizaki said:

DVI requires 17 pins minimum for a single link. 23 for dual link.

VGA requires 15 pins.

USB 2.0 requires 4 pins, USB 3.0 9 pins.

 

There are 25 pins on that guy.

 

So at best you could do a single link DVI and two USB 2.0 ports, if you did a direct attachment. Or VGA and USB 3.0

Its a 30 pole switch, five contacts aren't being used. Although VGA physically HAS 15 pins, they aren't all used. I count eight to switch over.

 

8 plus 17 is 25, and I need only 2 more for USB. Heck, I could put audio through the remaining pins and still have one leftover for an LED or something

[iamdarkyoshi]

42 minutes ago, glitchmaster0001 said:

wait what are you going to use that hub for? 

The USB hub or the device in general?

[vanished]

33 minutes ago, iamdarkyoshi said:

Its a 30 pole switch, five contacts aren't being used. Although VGA physically HAS 15 pins, they aren't all used. I count eight to switch over.

 

 

8 plus 17 is 25, and I need only 2 more for USB. Heck, I could put audio through the remaining pins and still have one leftover for an LED or something

You'll have to license your design of this marvelous all-in-one new format/connector when you're done

[vanished]

34 minutes ago, iamdarkyoshi said:

Its a 30 pole switch, five contacts aren't being used. Although VGA physically HAS 15 pins, they aren't all used. I count eight to switch over.

 

8 plus 17 is 25, and I need only 2 more for USB. Heck, I could put audio through the remaining pins and still have one leftover for an LED or something

Also, in that picture, I see a lot of "ground".... has anyone tried just making pins 5 through 11 all connect to one wire? 

[iamdarkyoshi]

5 minutes ago, Ryan_Vickers said:

Also, in that picture, I see a lot of "ground".... has anyone tried just making pins 5 through 11 all connect to one wire? 

5,10, and 11. Those are pretty much chassis ground or logic ground, the RGB grounds are more of a signal ground and will be switched. Might cause ground loop interference if they were joined to chassis ground. Also, with this thing being in a metal chassis, I will just solder the ground wires to the shells of the connectors lol

 

7 minutes ago, Ryan_Vickers said:

You'll have to license your design of this marvelous all-in-one new format/connector when you're done

I shall call it "Displayport" and it will look like this:

[glitchmaster0001]

2 hours ago, iamdarkyoshi said:

The USB hub or the device in general?

The device in general and also your project that you are planning to do with it

[iamdarkyoshi]

7 minutes ago, glitchmaster0001 said:

The device in general and also your project that you are planning to do with it

A KVM Switch (KVM standing for Keyboard, Video, and Mouse) allows you to connect to two PCs and switch between them. This one will be used in my garage. Normally, I would just have my garage PC selected. By switching from A to B, I can now control another PC (such as a friend's PC if I am working on it) without swapping any cables.

[glitchmaster0001]

5 hours ago, iamdarkyoshi said:

A KVM Switch (KVM standing for Keyboard, Video, and Mouse) allows you to connect to two PCs and switch between them. This one will be used in my garage. Normally, I would just have my garage PC selected. By switching from A to B, I can now control another PC (such as a friend's PC if I am working on it) without swapping any cables.

wow thats pretty cool. please post updates on your project! 

[Unimportant]

I doubt it'll work, i can only imagine how much parasitic capacitance that switch has but it's probably trough the roof and will screw up any high frequency signals.

 

VGA will work, as it's a analog signal, colors might bleed a bit, specially at high res,  and other distortions, but it'll work. But high speed digital signals like USB and DVI will probably get corrupted and fail.

 

You can always try tough, keep us informed.

[iamdarkyoshi]

23 minutes ago, Unimportant said:

I doubt it'll work, i can only imagine how much parasitic capacitance that switch has but it's probably trough the roof and will screw up any high frequency signals.

 

VGA will work, as it's a analog signal, colors might bleed a bit, specially at high res,  and other distortions, but it'll work. But high speed digital signals like USB and DVI will probably get corrupted and fail.

 

You can always try tough, keep us informed.

Yeah stray capacitance might be an issue, but might not, we shall see. USB seems the most likely to work fine TBH, I have had cables eaten by a cat before and I had to use them while at school, stripping the wires with a scissors and twisting them together had no issues transferring data to my tablet, and the cable in question wasnt even shielded

[WEEEEEE]

On 6/14/2016 at 9:59 PM, iamdarkyoshi said:

I shall call it "Displayport"

You should perhaps consider calling it thunderbolt instead.

 

[Huntsman]

If your're using shielded cables, then it should work fine. But some of the connections are twisted paired together, so you technically can't twist the wrong pairs else there would be significant crosstalk

[iamdarkyoshi]

Update: got most of my IO. Still need two type B USB connectors. To craigelist!