PDA

View Full Version : Alternate Cabling Solutions



xyzzy1126
03-21-2007, 11:20 AM
So I was walking around my office today. and I saw some CAT5 (ethernet) cable sitting in a trash can. That made me think, "Hmm, I wonder if such cable could be used with Phidgets components."

I remember seeing a graphical tutorial on how to use stereo cabling with a 1/8" jack as a "hybrid" cable. This seemed nifty, since once you have that "Phidget to stereo" interface, you can run any length (within limits) of stereo cable.

http://www.phidgetsusa.com/tutorials/tutorial_custom_cables.asp

However, I'm thinking of trying this with tha CAT5 stuff. At first, I was just considering pulling the wires out from the outer cover, but then I realized something: "Eight wires... hmm... The mini joystick could use three per axis, and two for the button. I could just use the ethernet cable as is, and splice the ends into the joystick (and into the InterfaceKit on the other end)."

If I wanted to get even fancier, I could run a short (inch or two) length of wiring from the joystick leads to a CAT5 jack, do the same with the InterfaceKit, and then use a regular ol' pre-cut and crimped ethernet cable to connect between the two units. This would let me rig up the jacks "external" to the components, rather than plugging directly into them (as they might be mounted inside some housing or another).

Of course, I would need to pay attention to things like how far I'm running this cable, what the resistance is on the wires, noise from so many wires being bundled up so closely to each other, and (of course) making sure I match up both ends correctly.

So, does anyone see anything wrong with this? Or does it sound like a plausible idea. (I edited this post down a bit for the sake of brevity)

Alex
03-21-2007, 03:24 PM
That sounds like a brilliant idea! The only thing that I'm thinking of is to keep in mind the fact that the longer the distance the analog signal has to travel the less accurate your signal will be. Dave might be able to better shed some light on all of this though.

Aside from that definitely as you had already mentioned though:



Of course, I would need to pay attention to things like how far I'm running this cable, what the resistance is on the wires, noise from so many wires being bundled up so closely to each other, and (of course) making sure I match up both ends correctly.

Take some pics, and paste them here!!

xyzzy1126
03-22-2007, 09:44 AM
That sounds like a brilliant idea!Heh, thanks. I can't help but think of those collage-lookin' Guinness ads with the two guys coming up with ideas and telling each other, "BRILLIANT!"


But yeah, I'd definitely have to be mindful of power loss or signal degradation over longer distances. I suppose if I wanted to get really fancy, I could set up some kind of in-line repeater. However, I'm just looking to go a few feet (for now).

Possibly an interesting use of this could be for home security/automation. It'd be nice to be able to just plug a component into a CAT5 wall jack and have it connected to a microcontroller thats hooked up to the PC, a room (or floor) away.

I'm just imagining being able to take a few reed switches, some motion sensors, maybe a pressure plate, and plug them all into a ethernet cable (or two) and pipe that through to the InterfaceKit.

Anyway, I guess if I want to do this, I should order a bunch of sensor cables to cannibalize for the connectors. Then I can work on wiring them up to ethernet jacks and run a cable between them. When/If I make some progress, I'll try to make some pictures available to share.

Alex
03-22-2007, 10:15 AM
Awesome!! Can't wait to see it in action:)

BTW, those Guinness commercials are where I got that from, haha! Using "brilliant" anytime any one of us comes up with a cool idea is kind of an ongoing joke around the office here:D

xyzzy1126
03-27-2007, 09:30 AM
Hi, I'm still interested in the custom cabling idea, I've just been a little too busy lately (and for the next week) to investigate too much more into it. However, I do have a few questions so far.

Primarily, I'm wondering about wire guages. A higher American Wire Guage (AWG) number means a thinner wire, and I'm not sure how thin is TOO thin. I guess if it's too thin (and depending on how much load you have across that wire), you can run the risk of the wire heating up, melting, or even catching on fire.

Now, I'm not worrying about it TOO much, I'd just like to get an idea of what range of guages is safe to use for getting data off sensors, completing a digital input circuit, or powering someting on the digital output port of the standard InterfaceKit.

The sensor cable that comes with a sensor appears to be 26 AWG, judging by the printing on the cable itself (not to mention the box crimp terminals used are rated for a 22-24 wire range). However, the 100-foot sensor cable available on the site is 28 guage. On top of all this, I also want to run across a standard CAT5 cable, which (I think) uses either 24 or 26 AWG twisted pairs.

Anyway, I just thought I'd ask and see if anyone had some ideas on this subject. Heck, it might even not make that big of a deal, so long as I'm not trying to power a huge motor over a 32AWG piece of wire. I guess I could just try different guages, and if anything starts to heat up (or there's a noticable degradation in a sensor signal), just use the next thicker guage.

While I'm posting, I may as well ask a second question I had on my mind: "Solid or stranded?" I guess the solid-core wiring is cheaper, but less flexible and has a shorter transmission distance than the stranded stuff. Also, I've heard its easier to crimp one of those tiny terminal pins/sockets onto a stranded wire. No biggie, just curious.

Lastly, when looking at components, what's the difference between the tin/lead-plated stuff and the gold-plated parts? Obviously, gold is going to be more expensive, and I'm guessing it has better conductivity than the tin/lead mix. Also, I'm assuming there's some negative connotation to working with lead in the equation, albeit a tiny amount.

For projects like these involving the InterfaceKit and sensors and digital in/out, is there much benefit to using gold-plated components, as opposed to the tin/lead stuff? Once again, this isn't something thats weighing heavy on my mind, I was just curious as to how things work.

Also, sorry if these are basic "well DUH" kinda questions. I'm relatively new to this area of electronics, and I'm just learning the ropes (or wires, as the case may be).

Dave
03-27-2007, 12:21 PM
Primarily, I'm wondering about wire guages. A higher American Wire Guage (AWG) number means a thinner wire, and I'm not sure how thin is TOO thin. I guess if it's too thin (and depending on how much load you have across that wire), you can run the risk of the wire heating up, melting, or even catching on fire.

Here's some helpful information about the current capacity and resistance of different wire gauges:
http://www.powerstream.com/Wire_Size.htm
With Phidgets, you don't really have to worry about high current, but it's still useful information to have.


I guess I could just try different guages, and if anything starts to heat up (or there's a noticable degradation in a sensor signal), just use the next thicker guage.I doubt this will be a problem. Of course, I'm not telling you to discard caution entirely.


"Solid or stranded?"This really comes down to the application. I'll skip over the physical differences because they're fairly obvious. Electrically speaking, if your wires are less then a few hundred feet long, the differences between the two are negligible (unless you're transmitting high frequencies, in which case you should know about the skin effect (http://en.wikipedia.org/wiki/Skin_effect)). If you want my two cents; I prefer stranded wire, unless I'm breadboarding or repairing a PCB.


...what's the difference between the tin/lead-plated stuff and the gold-plated parts?Gold doesn't oxidize, so your contacts will stay clean. Less contact resistance.


Also, I'm assuming there's some negative connotation to working with lead in the equation, albeit a tiny amount.[tree-hugger rant]
Lead is toxic. There may only be a tiny bit of it in each electronic component, but considering the ridiculous volume of electronics being produced, that's actually quite a bit of lead. We're thinking about the Big Picture, here.
[/tree-hugger rant]


For projects like these involving the InterfaceKit and sensors and digital in/out, is there much benefit to using gold-plated components, as opposed to the tin/lead stuff? Once again, this isn't something thats weighing heavy on my mind, I was just curious as to how things work.Shouldn't make too much of a difference.


Also, sorry if these are basic "well DUH" kinda questions.Hey, don't worry about it. This is what we do.

SnyperBob
07-14-2008, 04:15 AM
Sorry to revive an old thread, but I was also wondering if Cat5 would work OK for extending wires to remote sensors. I did a search on 'cat5' and this was the only thread that was found. I'll try some more searches for cat6 or cat5e or something and see what I get.

Anyway, I find it hard to believe no one has used cat5 yet. Does anyone know if this works well? Thanks!

ScuD
07-14-2008, 04:23 AM
Depends on what signals you're gonna send through the wire, what length etc.

Any more information?

SnyperBob
07-14-2008, 04:34 AM
Well, I don't really know exactly what I want to do yet. I'm thinking something like an 8/8/8 in my wiring closet in the basement. And have temp/humidity/etc sensors around the house. Longest run would be about 75-100 feet.

Adrenalynn
07-14-2008, 04:34 AM
In robotics we pretty infrequently run anything that needs more bandwidth than you can get out of Cat5e... You were the one pushing 16Mhz processors, ScuD. ;) 5e should be good for at least a hundred megahertz, 200-250mhz for Cat6.

Just don't try to carry motor current over it.

Adrenalynn
07-14-2008, 04:36 AM
Well, I don't really know exactly what I want to do yet. I'm thinking something like an 8/8/8 in my wiring closet in the basement. And have temp/humidity/etc sensors around the house. Longest run would be about 75-100 feet.

Typically that's carried over Catagory 3 [non twisted] for several hundred feet. Cat5 is fine.

My weather station transports temp, humidity, anemometer, rain gauge, etc. over Cat 3 for a thousand feet...

Just pay attention to your signal loss if you're getting out into the hundreds of feet.

ScuD
07-14-2008, 04:45 AM
16Mhz is way too high for my likes, I won't touch anything over 40kHz! ;)

Should indeed be fine for those kinds of sensors.

One little sidenote though; if you're sending an analog output from the sensor over those lines, given some distance you may want to take precautions if you don't want to compromise accuracy (eg. differential signals, matching, ...)

SnyperBob
07-14-2008, 04:48 AM
In robotics we pretty infrequently run anything that needs more bandwidth than you can get out of Cat5e... You were the one pushing 16Mhz processors, ScuD. ;) 5e should be good for at least a hundred megahertz, 200-250mhz for Cat6.

Just don't try to carry motor current over it.

OK, yeah, I think I'll be OK as long as I don't run motors over it. The temp sensors keep it under 5 volts I believe, so I think I should be OK running those over cat5e. That's all those 1-wire kits use

ScuD
07-14-2008, 04:53 AM
Ah, in case of the one-wire devices there'll be no prob.

SnyperBob
07-14-2008, 05:27 AM
well, yes...but I want to use a phidgets because they're so much smarter! lol

Adrenalynn
07-14-2008, 10:39 AM
In fact, using a Balun, you can even run USB over Cat5 for pretty good distances. I have balun installs out there of 300 and 4000 ft for USB.

I have a couple of 1000 ft 1024x768 video monitor installs in place running over "Cat7".

A-Bot
07-17-2008, 07:23 AM
My weather station

You have a weather station? :robotsurprised:

Adrenalynn
07-17-2008, 10:27 AM
Sure - just one of those silly high-consumer-end thangs. Davis Vantage Pro with anemometer, temp, rain, humidity, uv, solar radiation, soil moisture sensors.

Not one to CONTROL the weather YET. ;)

A-Bot
07-17-2008, 10:30 AM
Sure - just one of those silly high-consumer-end thangs. Davis Vantage Pro with anemometer, temp, rain, humidity, uv, solar radiation, soil moisture sensors.

Not one to CONTROL the weather YET. ;)

Is the tower on top of the Batgirl cave? :veryhappy:

Adrenalynn
07-17-2008, 10:46 AM
You don't want to know...

ooops
07-18-2008, 08:07 AM
What would be interesting would be to use one of those AC/phone plugs that "turns any outlet into a phone jack" and send the data anywhere within the circuit.
Add the clapper and you have data on demand.