PureBasic Forums - English

Yep, I need to enlarge an USB cord, is this possible with out "access points" or those hubs they sell ? (every cord is very expensive and those hubs are too, and I need this for outdoors so its totally idiotic to have this method implemented, it just wont work!).

Any other ports like parallel which might be easier to work with in terms of cord / wire length? I need 20 meters / about.

Thanks in advice, this is really important
I know about the voltage lose when the cord gets longer and longer.. but, I thought.. why not sending more voltage to the output? there must be some ecuation of maths that tells how big is the drop on which length.. no? If not im doomed. I'd say "enlarge the wire, plug the usb if it doesnt work, start feeding up the voltage till it works" .. but its risky. also wouldnt I have trouble with the motherboard ? - I think theres only a couple of voltage output wires out there.. if I have those, I can "implant" more voltage at the output on any part of the cable..

it could work but I dont have the appropiate hardware to send more or less voltage (although could do it with a potenciometer -sorry im spanish-). Uh oh.. why not giving the appropiate voltage at the hardware part? why does it have to travel in the wire anyway? I dont need anything nice.. just to work.

Parallel cables only good for a metre or so. Ordinary serial if proper twisted pairs good for 10m (IIRC) but my guess is neither of these is suitable for what you are doing... which is what exactly? I'd advise against messing with voltage levels because each device expects standard levels and you will probably fry one or both.

Do a google search for max rated length of usb cables. I know it's substantially longer than old serial cables. Exception is RS422(?) which is a two wire serial std which varies current rather than voltage and is used in industrial control systems.

Other alternative... network cable! 200m I think.

This is for a webcam, I cant use anything else... if the cam is usb, the idea is to have nothing else than the cable. And its easy to check how many voltage the device needs, thats no problem at all.. my question is, if I add the correct voltage to the device (and supress the one of the usb.. or not, blend them maybe) would it work?... I always had this idea in mind but never wanted to "fry" like you say, a device just for testing.

In theory it should work, although I have a bad feeling, idiotic one!.

im not sure network cables would work. Its a matter of how long the power can reach im not sure how much a webcam needs, but im not quite sure it could be done with a usb cable. of course its worth a try with a cable.
as dmoc i wouldnt mess with voltage levels. I would buy a wireless webcam. Now what are you going to spy? the beautifull lady next door?

Why is everyone so shy about electronics? they dont bite, they just kick you a little if you're with high voltages.. but thats about all (not the case here.. so why be shy) I dont think the energy goes back to the mobo.. dont think so. And if the voltage loss is because of the length of the cord, then if you "feed" the device with another source, it should work.. At least the USB peeps said its a voltage loss (via email, last time I emailed them was in 2002).

I agree with thefool re wireless cam. This link gives you important info...

http://www.usb.org/faq/ans5/

Not being "shy" about electronics ( ) I would be tempted to at least try a length of good quality cable (cat5 ?) Splice it into an ordinary usb cable but use an external powered hub near your pc. Cheap and limits any damage. May work because standards usually design to ensure stuff works but you can push thm a bit. There again, cat5 cable is cheap but cost of powered hub may just make it worthwhile going the wireless route (I've no idea of prices).

it wasnt high voltages i was afraid of its just that its not sure your webcam would like it

You know those filters they sell so a light-strike wont f***k up your dsl modem and so... (for 56k too, in fact I dont think they work with some DSLs anymore... or they might of have new ones).. they are a simple diode inside a plastic case... in fact they can make it look more complicated by creating a diode out of other components.. but no they have a 2 diode system which limits a high voltage to get inside your modem. anyway.. I think I can manage to work on a hub, after all... its just powering up the output. I dont think it touches the data, it might have a voltage stabilizer built-in ! which is no problem (I might use triacs maybe, those are fast) and well I will try with my way first.. but if I end up with a burned up cam.. hmm what would you do with it? lets do a contest :p

I'd shoot it with a 4.5 pellet rifle. (with 10 pumps its as powerful as a .22lr is) streight up the lens (although the poor lens has no fault.. I might keep them) and if it really burns up, it might have a resistance there.. which a replace would possibly fix. You know those cold-cathode home lights they sell? those that are 14Watts but they light up like a 60watts tungsten... I dont know the english name of them, anyway... their ignitor is quite simple, and some components might get burned up before the tubes life runs away, this could be caused by some electric anomalies (ups most than downs.. if the components recieves more than 230v its commonly to stress and end up pretty bad) just with a few peaks!..

Well the whole point is that I remember when I used to fix them (yeh fix a lamp, sounds weird) but they usualy lasted longer than brand new, because of the component replacement for better quality ones... Cheaper at the end? no.. but its fun to fix anything you want! So far the only thing I could not fix yet, its my RC controller (for my plane).. oh well now THATS complicated, its very complex system, and I think the problem is at both emissor and reciever. Will look later again. Its easier to fix a CRT screen, 10 times easier (most causes are defective flashback... even broken pins at the vga connectors! I've had to fix 2 screens with that problem already.. its tipical from bad handling!!, and so on.. just remember that even if you discharge your monitor.. you'll get shocked if you dont wear protection gloves -yes its true remanents of power stays on the capacitor, hard to believe, but bad o recieve so dont even try or you'll end up cutting your hand when you take it out so fast of the monitor case , happens- )

oh alright enough blahblehblah back to work and breakfast!.

dagcrack, I suspect you are bored and need distraction. I recommend (with EXTREME caution!) this site...

http://www.powerlabs.org

Um already know of... Seen the guy at junkwars as well, many chapters ago.
I was just saying.. But yes I have been working hard here, and distraction doesnt help at all.

Why don´t use wireless connection ?. You can buy any guizmo like wi-fi or bluethoot with USB port ready.
Good luck

Hello

I really doubt a cat5 cable would do the job due to insufficient sheilding.
I would never induce a higher voltage in this type of application. Mainboards have sensitive voltage regulaters. A USB cable has a positive and a ground wire which means the voltage and current does return to the PC. I believe it is called a closed circiut.

I checked out a couple of commercial sites which I have no affiliation with and came up with the following info.

http://www.inkjetart.com/usb/

In practice, the USB specification limits the length of a cable between full speed (12 Mbps) devices to 5 meters (a little under 16 feet 5 inches). For a low speed device (1.5 Mbps) the limit is 3 meters (9 feet 10 inches).

http://www.vpi.us/usb-extender.html
It can also be extended up to 25 meters according to the above site.

Good Luck

for long cables on usb you need an 'usb extender'... good ones will convert usb to cat5 and back, and make links (usb1.1) possible over a 100 metres

you all commercial kids! the idea is to make it not to buy it

USB cables aren't just about the voltage levels.... the limit in length is due to the reflections of the signals causing problems with the next bit of data being transmitted. You can't just splice in a chunk of extra wire in a USB cable and hope that it will work, like you can with parallel or serial cables. Increasing the voltage in the USB cable really really won't work.

If you really want to build it instead of buying it, you'll end up duplicating what the real USB extenders do anyhow (like convert to ethernet or rs485 for the long haul link). You'll end up paying more to build the thing than it would cost to buy the extender.

From a FAQ at www.abacus.co.uk/

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Cables and Long-Haul Solutions

1. Why are there cable length limits, and what are they?
A: The cable length was limited by a cable delay spec of 26ns to allow for reflections to settle at the transmitter before the next bit was sent. Since USB uses source termination and voltage-mode drivers, this has to be the case, otherwise reflections can pile up and blow the driver. This does not mean the line voltage has fully settled by the end of the bit; with worst-case undertermination. However, there's been enough damping by the end of the bit that the reflection amplitude has been reduced to manageable levels. The low speed cable length was limited to 18ns to keep transmission line effects from impacting low speed signals.

2. I want to build a cable longer than 5 meters, why won't this work?
A: Even if you violated the spec, it literally wouldn't get you very far. Assuming worst-case delay times, a full speed device at the bottom of 5 hubs and cables has a timeout margin of 280ps. Reducing this margin to 0ps would only give you an extra 5cm, which is hardly worth the trouble.

3. What about using USB signal repeaters to make a cable longer than 5 meters?
A: Don't bother. The best solution is self-powered hub with a fixed 10m cable that had a one-port bus powered hub in the middle. The maximum range will still have to deal with the timeout, so any out of spec tweaking of the terminations between the two hubs and the timing budget still won't yield more than 5cm of extra distance. A better solution is described in the following question.

4. I really need to put a USB device more than 30 meters away from my PC. What should I do?
A: Build a USB bridge that acts as a USB device on one side and has a USB host controller at the other end. Use a long-haul signalling protocol like Ethernet or RS-485 in the middle. Using cables or short-haul fibre, you can get ranges upwards of a kilometre, though there's no reason why the long-haul link in the middle of the bridge couldn't be a pair of radio transceivers or satellite modems.
Embedded host solutions capable of doing this already exist. Also, two PCs connected via USB Ethernet adapters are essentially a slave/slave version of this master/slave bridge.

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