The universal converter box - Page 1
Forum section: electronics / general

author: Stonent
author_rank: Super Contributor
timestamp: August 13, 2014, 02:39:34 am
content: From:http://xkcd.comWe all have those people who see that you're an engineer or in IT and says "Hey is there a cable that will convert %Incompatible Technology 1% to %Incompatible Technology 2%?

author: GeoffS
author_rank: Unknown
timestamp: August 13, 2014, 03:04:16 am
content: Fixed that.Randall also provides a link to an image of the comic for this sort of use.

author: SirNick
author_rank: Frequent Contributor
timestamp: August 13, 2014, 03:06:32 am
content: Bought one. Doesn't come with cables. Would not recommend.

author: Stonent
author_rank: Super Contributor
timestamp: August 13, 2014, 03:21:25 am
content: Quote from: GeoffS on August 13, 2014, 03:04:16 amIt wasn't intentional. I got the picture off of a facebook feed I watch.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 13, 2014, 03:22:42 am
content: Funny thing is, there's a chip for almost any pair of those standards, though no such thing for all; and many of the strictly-incompatible types can still be converted in some useful manner.Example: fuel can be converted to electricity (though not the opposite direction, at least very efficiently just yet), and from there to any voltage or frequency you might desire.Comm standards with power (like USB, or good old serial -- curiously absent, actually) can convert to electricity (like the NEMA 5-15P), though arguably at a fraction of the practicality (enough to run a nightlight perhaps?). The opposite, of course, is true of USB chargers.Perhaps the funniest part is that, despite the possibility of its existence and the frustrating demand for it, such a product won't exist -- it would be much too expensive!Tim

author: Stonent
author_rank: Super Contributor
timestamp: August 13, 2014, 03:28:07 am
content: About 13 years ago I worked in a research building at a pharma company and there was a comic on the wall in our area that had two people on the phone and one said "Can you tell me how to hook my computer to my phone so I can fax this VHS tape to my friend's printer?"

author: Stonent
author_rank: Super Contributor
timestamp: August 13, 2014, 03:36:00 am
content: Quote from: T3sl4co1l on August 13, 2014, 03:22:42 amThe thing I see a lot are the people who want to hook things together in a way that won't work.One guy kept asking for us to order him a USB A to A cable and we of course asked him what he was trying to connect and he said "Just order me the cable ok?"Usually I try to explain to the people the numerous times I've heard this question is that in 95% of cases you can't hook USB up that way because it's not peer to peer, it's master/slave. One side has to be a master and one a slave.The other common one is people who are absolutely sure there's something that looks like an analog phone line splitter but for RJ45 Ethernet. I had one person accuse me of just being difficult because I said that Ethernet doesn't work that way, you need to run it off of a hub or switch. Since we're a large company we don't just go hanging $25 Linksys or netgear equipment off of our multi thousand dollar cisco hardware to add more ports so he'd have to put in a requisition for a new line.As I was leaving I overheard one guy say "Dude, don't listen to him just go to the store and buy a splitter"

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 13, 2014, 03:48:56 am
content: Ironically, ethernet does support limited P2P2P:http://electronics.stackexchange.com/questions/10864/building-a-passive-ethernet-hub-with-anti-parallel-diodesRegarding USB, we recently had an oopsie, putting USB-mini on the host end. To be fair, the customer suggested the connector type, and probably just didn't get around to testing it with their initial prototype to experience the 'duh' moment. Remarkably, such a cable actually exists, so it's not even cutting into the testing schedule.Tim

author: gxti
author_rank: Frequent Contributor
timestamp: August 13, 2014, 04:02:07 am
content: Companies that are really cheap sometimes run two 100Mbit ports over a single 4-pair cable, because 100BASE-TX only uses 2 pairs. But it's always terminated behind the jack, I doubt you'd be able to readily find such a "splitter". Plus we all know that's not what this guy was actually trying to do, otherwise he would have been able to articulate it better.

author: Stonent
author_rank: Super Contributor
timestamp: August 13, 2014, 04:15:07 am
content: Quote from: gxti on August 13, 2014, 04:02:07 amAs a matter of fact that was exactly what I encountered in his area as well. Turns out one of our former employees used to like to split pairs like that to save on having to have cables run. It's a bit of an issue now because we can't run VOIP phones in those areas so they are stuck on analog phones. This year we're supposedly getting rid of all our "Brand X" voip system and analog lines and going to some decent equipment. Those areas will have to be rewired because the split lines can't do PoE.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 13, 2014, 06:31:02 am
content: Quote from: Stonent on August 13, 2014, 03:36:00 amI read this & thought "Huh!",as I was sure I had used just such a cable.It turned out to be a USB "A" male to female extension,but just for kicks I GoogledUSB "A" to "A" cable,sure enough,they make a male to male cable---what it is for is beyond me.In one of my last jobs (in manufacturing) before retirement,they apparently had problems finding panel or PCB mount USB connectors,so they decided to use some cable which the EE said "had better specs than normal USB cables",terminated both ends in hand soldered round multipin connectors.I cringed everytime I had to wire one of these,& went to great pains to use HF wiring techniques,but others didn't seem to bother,treating them like audio connectors.USB2 is pretty rugged,though,& it worked OK.

author: G7PSK
author_rank: Super Contributor
timestamp: August 13, 2014, 08:01:37 am
content: I had 2 A to A USB cables that came in a job lot I got. did not find a use for them for years and so cut one up to change an end one day but then I got a cheap 2.5 inch hard drive caddy on e bay and what was the socket on it. You guessed an A type USB and no they did not supply any leads with it so a hurried scrabble through the cable bin for the remaining A to A.

author: VK3DRB
author_rank: Super Contributor
timestamp: August 13, 2014, 12:34:38 pm
content: It is useless. It has no DB-9 connectors. Or null modem cables.

author: corrado33
author_rank: Frequent Contributor
timestamp: August 13, 2014, 12:58:45 pm
content: I'm actually very surprised a high quality device similar to this hasn't come out. Not for converting random things to other things, but just for charging. All the ones you see are cheap crap from china. I mean, how hard would it to be to have the magsafe connectors, old and new iphone connectors (multiple) in one device? It's probably proprietary, now that I think about it. (The magsafe)If I designed one, I'd design it with retractable cables and a beefy spring and nice rubberized feet to hold it in place.

author: Bored@Work
author_rank: Super Contributor
timestamp: August 13, 2014, 01:37:04 pm
content: Epic fail. No garden hose interface.

author: N2IXK
author_rank: Frequent Contributor
timestamp: August 13, 2014, 02:55:13 pm
content: No binding posts for raw stripped wire?Reminds me of a joke "cable" I made up and had hanging in my shop for years. Fiber optic connector on one end, to a pair of alligator clips on the other...

author: AG6QR
author_rank: Frequent Contributor
timestamp: August 13, 2014, 03:02:49 pm
content: It should have banana jack breakouts.Seriously, I do have a "this to that" box where I just installed one of every common kind of two-conductor connector I use, all in parallel. I've found it very useful on more than one occasion. It at least works at DC and audio frequencies (the signal integrity might not be so great at higher frequencies). BNC, banana jacks, 1/8 audio, 1/4 audio, RCA, 2.1mm DC power jack, etc.But it doesn't have anything inside to change protocols...

author: gregallenwarner
author_rank: Regular Contributor
timestamp: August 13, 2014, 03:37:54 pm
content: Quote from: N2IXK on August 13, 2014, 02:55:13 pmThat reminds me of the "Etherkiller" cable I made at my first job as a joke. RJ-45 on one end, NEMA 5-15P on the other!Thankfully, no one tried to plug it in.

author: SirNick
author_rank: Frequent Contributor
timestamp: August 13, 2014, 06:42:18 pm
content: Quote from: vk6zgo on August 13, 2014, 06:31:02 amI don't know for sure, but two things spring to mind:1) USB OTG. I haven't studied up enough to know if this particular combination is used, but there are some weird (and counter-intuitive if you know what you're doing) practices going on there. I'm not quite sure if the whole implementation was a good idea or a really bad one.2) I vaguely remember there being a data transfer product (maybe Lap-Link or something similar) that used an A-to-A cable, but I assume it had some active electronics in the middle.Quote from: T3sl4co1l on August 13, 2014, 03:48:56 amI considered making something like this in one of those wall biscuits once. I was installing an active/standby firewall pair and needed a way to get both devices connected to a single Ethernet WAN feed. There was only one incoming cable and it would've been prohibitively expensive to run a second from the demarc.One option was to use the smallest Cisco (8-port with PoE) switch we had, but they're not exactly cheap, used (limited) rack space and another power outlet on a full UPS, and presented one more single point of failure that somewhat negated the point of redundant firewalls.Option B was to go cheap and use a commodity switch, but they're so unreliable that ittotallynegated the point. (Although in reality, they're used A LOT in commercial networks, like when those fancy managed devices fail to negotiate with each other.)I figured passive electronics are pretty reliable, so why not a passive hub? Management ended up going with option C: When the Internet goes down, swap the cable over.Hey, what's $50k for a cold standby firewall in the scheme of things?I have yet to find a commercial-grade three-port Ethernet switch. If anyone knows of one, I would be obliged.

author: Kevman
author_rank: Regular Contributor
timestamp: August 13, 2014, 07:14:55 pm
content: Quote from: Stonent on August 13, 2014, 03:36:00 amhttp://www.amazon.co.uk/Belkin-R6G029-2-Port-Passive-Hub/dp/B0002AF8VOMy sister was given one of these in college (late 90s) to plug her and her roommate's laptop into. They both worked at the same time, I'm not sure how.I still have the splitter, but its useless.

author: justanothercanuck
author_rank: Frequent Contributor
timestamp: August 13, 2014, 10:22:54 pm
content: Quote from: Stonent on August 13, 2014, 03:36:00 amRun a trap that detects MAC address changes on switch ports, and when he plugs in his newfangled "splitter", disable the port, walk into their room, rip it out and tell them to stop circumventing your network policies. Hand them back the device, since you technically can't keep it, and tell them the port won't be enabled until they start playing nice... and that if you see that device again, you'll keep disabling ports and talk to upper management.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 14, 2014, 02:29:20 am
content: Quote from: Kevman on August 13, 2014, 07:14:55 pmI tore down something similar and it's just a just a passive adapter. 10/100 only uses 2 of the 4 pairs, so all the adapter does is allow a second Ethernet connection to run on the other 2 pairs. At the other end, another adapter or some other way to combine two ports into one line are needed.