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PostPosted: Sun Dec 14, 2008 11:44 pm 
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I thought about the drill press and etching issues and just realised now that instructables has a huge amount of information about this.

DIY PCB Drill http://www.instructables.com/id/DIY-Pcb-Hand-Drilling-Machine/

Etching with an inkjet http://www.instructables.com/id/Cheap-and-Easy-Toner-Transfer-for-PCB-Making/

PCB drill press 1 http://www.instructables.com/id/PCB-Drill-Press-Using-Salvaged-Door-Hinges/

PCB drill press 2 http://www.instructables.com/id/%2430-High-Speed-PCB-Drill-Press/

Maybe that is more helpful.


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PostPosted: Sun Dec 21, 2008 5:34 pm 
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Thanks for the info! Definitely will give it a look.

Anyway, as requested here's the schematic for the usb switch. As you can see, it's a simple switch. There's no device that tricks the computer into thinking that the device is connected even though it's not. I will gladly test any ideas in this area.

Through my testing I found that leaving the power connected doesn't make much difference; the only actual effect is that it allows whatever device is connected to draw twice as much power as usual.

In my project (which I am proud to say is progressing) I am using the 4066's that Ron suggested because I plan to have LED indicator lights and such. The 4066, or a few of them, is necessary when the data cable being switched has more than two data wires (i.e. a dvi cable). But since usb 2.0 has only two data wires, a dpdt switch can be used.

I'm still learning how to use eagle light and it was a lot easier to draw a dpdt than all the wiring for a 4066 :wink: (on that note, how do I get a plain old 14-pin DIP in my schematic?)

Image

just a warning... If you plan on building this, double check your wiring. I accidentally crossed two wires yesterday and all the USB ports on my 680i stopped working until I rebooted LOL...


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PostPosted: Sun Dec 21, 2008 11:14 pm 
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Thanks. Which 4066 did you use? I haven't used eagle before so I can't help with the DIP.


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PostPosted: Mon Dec 22, 2008 2:20 am 
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KVM to USB with a learning curve tossed in. :)

You have taken this and really run with it. Pretty cool.

Ron


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PostPosted: Mon Dec 22, 2008 5:39 am 
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Thomtzvi wrote:
Thanks. Which 4066 did you use? I haven't used eagle before so I can't help with the DIP.


http://www.mouser.com/Search/ProductDet ... rTUg%3d%3d

These ones. As I mentioned previously, I used a supply voltage of 18v which yielded around 60 ohms of on resistance. I think that somewhere above 100 ohms of resistance, USB data starts having trouble.


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PostPosted: Mon Dec 22, 2008 5:41 am 
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Thomtzvi wrote:


I think I am going to try to build this. I might have to come up with something a little different though.

I also want to build a CNC machine... but I feel as though I wouldn't be able to use it as much.


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PostPosted: Tue Dec 23, 2008 12:09 am 
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I will order some parts from mouser in the new year.

Quote:
I also want to build a CNC machine... but I feel as though I wouldn't be able to use it as much.


http://blog.makezine.com/archive/2008/12/make_gift_guide_for_the_c.html
A lot of good CNC info

I had a crack at eagle today and made an updated schematic.
To load a 4066 click use then search 4066N(a DIP instead of a SMT)

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PostPosted: Tue Dec 23, 2008 5:37 am 
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About this time you guys may want to look at another member of the CMOS family. You may want to look at the 4013 D Type Flip Flop.

That may be a nice clean way to eliminate the mechanical switch for your 4066 gates. I can see where using a 4013 with a NC push button would work pretty good. A few LEDs could be added as a visual indication of which outputs are selected.

Ron


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PostPosted: Tue Jan 20, 2009 2:03 am 
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I searched USB in the eagle parts libraries and found maxim IC makes a USB 2.0 DPDT switch, much faster and easier to manage than all the 4066s and 4013s, just have a button connecting or disconnecting Vcc from the output control pin. Then I found it was uDFN, no pins and 2x2mm, way too small for me to solder. Over the past week I have been doing some research and found that there are three products which could be extremely useful, using the same premise to tell the chip to switch outputs. The first is a TSSOP 48 pin chip from fairchild semiconductor which supports 1080 DVI and HDMI switching. Even better the pins are reasonable at 065mm. The data sheet is below.

http://www.fairchildsemi.com/ds/FS%2FFSHDMI04.pdf

The next is a QFN SPDT switch from texas instruments which has 0.5mm pins. It supports 480Mbps USB 2.0.

http://focus.ti.com/lit/ds/scds220f/scds220f.pdf

The third is a breakout board for QFN called schmartboards which looks very convenient except it is not available for TSSOP. The TI chips would be perfect for audio and ethernet as well. Perhaps the dream of a custom KVM is not yet dead, anyway for what a KVM costs here that doesn't have support for half the features I want I could build a custom KVM using these chips half a dozen times over. For PCBs I have heard olimex is good and their prices are cheap too. I have not made a schematic as there are no components in the existing libraries, although I will get around to it.

EDIT: I was thinking about the KVM switch today and on of the problems about schmartboards, you end up with some very large boards and not so large boards from freeware eagle, then I thought about one of the features of schmartboards, it has a modular design with jumper cables. With eagle you could create four boards, all with headers acting as pillars and as headers. This way you can have three boards with ports and one with all the ICs and if necessary another with the power connections, voltage regulators and all of that sort of thing. By doing so you can make a very compact KVM with a lot more power than regular KVMs that will suit any needs you may have. I will draw up a diagram to better explain this later. This may also help avoid more than two layers in a PCB keeping the cost down.


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PostPosted: Sun Feb 22, 2009 3:12 am 
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looks like you have a bandwidth issue I would check the specs on the cmos chips you got and verify that you are not exceeding the bandwidth with your high def div cable. Also you should use twisted pairs to avoid cross talk.


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PostPosted: Sun Feb 22, 2009 3:17 am 
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also you should check out Fairchild Semiconductors web site under video switching. It should help with your issue.


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