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Do you have to tie grounds together to get an arduinos IO to works with other...

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Nusa:

--- Quote from: Beamin on October 21, 2018, 05:39:55 am ---
--- Quote from: dmills on October 20, 2018, 10:33:19 am ---Cable telly rides on coax, which last time I checked has a centre conductor AND a surrounding (typically) foil shield, hence two wires.

That it is also wideband RF is irrelevant.

Regards, Dan.

--- End quote ---

Think about it if you send down RF you don't have to worry about the ground you are just using copper instead of air and the ground doesn't matter its just a shield. I'm almost positive they do that because it would be easier to upgrade from the old system.

--- End quote ---

I propose a test since you are almost positive.

Take your TV coax, pick a spot anywhere you like, strip off 1 inch of the shield without breaking the core (can be done with a knife if you don't have the right tool), and see if it still works.

Assuming you get the result I expect (not working), connect the two shields with a wire jammed in each side and see if it suddenly works again.

Now replace the cable you ruined. Or if near the end, cut it off and put a new connector on it.

[A less destructive version of this would be to undo your cable connector from the modem, stick a piece of wire in the modem middle and connect it to the center wire of the wire connector. With a micrograbber, for instance. See if it works. Now connect the outside shields, perhaps with alligator clips. Test again.]

GeoffreyF:

--- Quote from: PointyOintment on October 17, 2018, 09:41:25 pm ---You can also, at high enough frequencies, complete the circuit using capacitance. This is how Tesla coils work, for instance: It looks like there's only one wire going to the topload, but there is sufficient capacitance between the topload and ground (the literal ground it's standing on) to pass enough current at the operating frequency.

--- End quote ---

Love to see your Arduino connected directly to a Tesla coil. Pictures would be really awesome to see.

Buriedcode:

--- Quote from: Beamin on October 20, 2018, 07:56:40 am ---
--- Quote from: Nusa on October 20, 2018, 07:41:38 am ---If there isn't a circuit, no current will flow, and no signal will travel. Doesn't matter what you do at the input or output pins if there's only one wire connected and no ground path to complete the circuit.

This is practically the first thing you learn in any electricity tutorial/book.

--- End quote ---

Yes I know that but my question was how to do it. You often see in designs to build things with one output but I'm guessing they are omitting the ground because its common sense.

For instance your cable TV runs off one conductor to a station miles away. Unless that works off RF where they are sending RF down a cable instead of an antenna but that would be a signal with no return path.


--- End quote ---

Can you provide examples of what systems/connectors you believe to have "one output" ? I know many connectors look like they just have one connection - the center - they they also have surrounding metal often as a ground, which is also used as the shield (balanced lines also have their shield as the ground reference).  I've read the thread, and its quite hard to tell if you're joking, or you've managed to "do" electronics all this time without realizing that voltage is a potential difference. 


--- Quote from: Beamin on October 20, 2018, 07:10:29 am ---Are you talking about that thing on some computer mother boards that looks like a battery but is actually a security device? I always thougt that wasn't really one pin but the case was grounded. How can they possibly do that; the output pin can go above and below 0 effectively making 1 and 0 over one wire: 1t would be +5v for 1 and 0 would be -5 volts. But how would that get power?, a cap inside that recharges when you first turn it on?

--- End quote ---

I have never seen such a security device on a PC motherboard.  "One-Wire" could I suppose be used on PC motherboards, but that's just the spec.  I think you are referring to these devices? https://en.wikipedia.org/wiki/1-Wire#/media/File:I-button.jpg  That use the one wire protocol: https://en.wikipedia.org/wiki/1-Wire  .  I have never seen one on a PC motherboard, but I have seen coin batteries used for bios/RTC backup, could that be what you're mistaking for "not a battery" ?

As I said, I can't tell if you're serious... so apologies if I come across a bit rude.

GeoffreyF:

--- Quote from: Beamin on October 20, 2018, 07:56:40 am ---
--- Quote from: Nusa on October 20, 2018, 07:41:38 am ---If there isn't a circuit, no current will flow, and no signal will travel. Doesn't matter what you do at the input or output pins if there's only one wire connected and no ground path to complete the circuit.

This is practically the first thing you learn in any electricity tutorial/book.

--- End quote ---

Yes I know that but my question was how to do it. You often see in designs to build things with one output but I'm guessing they are omitting the ground because its common sense.

For instance your cable TV runs off one conductor to a station miles away. Unless that works off RF where they are sending RF down a cable instead of an antenna but that would be a signal with no return path.

--- End quote ---

Actually, on what you state with Cable TV, NO.  The shield is a conductor, it is grounded, it is the return path.  It doesn't come from miles away, it comes from an amplifier or other equipment hundreds of feet away.   Although the return of a circuit is not always a ground, there is always a return. That  is why they are called "Circuits". Even old fashioned Telegraph circuits which uses the actual ground for the return, still has a return path.  You say you come here for clarity but it seems like you turn from it or introduce speculations instead of the explanation which you sought.  The concept of "Potential" or voltage is based on the idea of a circuit or a path of return for charge carriers, such as electrons.

tooki:

--- Quote from: Beamin on October 20, 2018, 07:10:29 am ---
--- Quote from: IDEngineer on October 16, 2018, 03:51:29 pm ---
--- Quote from: rstofer on October 16, 2018, 02:20:05 pm ---There are no one-wire circuits.
--- End quote ---
WHAT?!? You mean Dallas Semi was lying to us all this time?!?  :palm:

--- End quote ---

Are you talking about that thing on some computer mother boards that looks like a battery but is actually a security device? I always thougt that wasn't really one pin but the case was grounded. How can they possibly do that; the output pin can go above and below 0 effectively making 1 and 0 over one wire: 1t would be +5v for 1 and 0 would be -5 volts. But how would that get power?, a cap inside that recharges when you first turn it on?

--- End quote ---
Uhhhh… no. IDEngineer was referring to the 1-Wire standard, which was designed by Dallas Semi.

As for the alleged security device: Ummm, are you sure you aren't confounding various conspiracy theories and other technologies? Right now, there's the Bloomberg story about alleged covert security implants in SuperMicro server motherboards, which is probably false. (I am incredibly excited to see how that clusterfuck resolves!!)
Dallas Semi made battery-backed RAM modules that were commonly used in 70s/80s equipment. They're common in test gear for storing calibration constants and user settings.

Do you have an example of or reference to the "battery [that] is actually a security device"?



--- Quote from: Beamin on October 20, 2018, 07:10:29 am ---How can they possibly do that; the output pin can go above and below 0 effectively making 1 and 0 over one wire: 1t would be +5v for 1 and 0 would be -5 volts. But how would that get power?, a cap inside that recharges when you first turn it on?

--- End quote ---
What are you referring to?

FYI, 1-Wire is basically a 3 or 5V bus (provided by a pull-up resistor) that transmits ones and zeros by pulling the bus low (0V, not negative!!) for different periods of time. (A capacitor in the device keeps it powered while it does this.)

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