Carrier current communication on Low voltage/high current AC

[Joerg]

Hello Spehro,

Some carrier current transmitters may go up to 50 Watts. That might overcome the
attenuation from a few line filters

With respect to mains applications there is also a legal limit and most
likely some further regs imposed by the utility.

From cost and EMI considerations, I was thinking more of <100mA at
100mV or so. ;-)

Some that I had seen just pound logic level onto the line, via a stiff
driver and a resonant circuit. The driver was often a plain old
transistor because it cost a few cents less than a driver. On the line
there may only be a volt or so left but that would be plenty if there
aren't too many EMI measures inside the loads near the receiving end.

The trouble with X10 is that it's an AM protocol and if the level at the
receiver drops below 100mV (which it easily does) reception becomes
flaky. FM should be much more robust. Just make sure no harmonics will
get you into regulatory trouble. That is another reason why a lower
frequency can be an advantage. Personally I wouldn't go to 455kHz.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Mike,

From cost and EMI considerations, I was thinking more of <100mA at
100mV or so. ;-)

That might work if the transmitter and receiver share the same plug

LOL! That was a good one.

For X10, yes. For a good FM scheme you'd have lots of dB of head room
but it depends on the noise that rides along.

Regards, Joerg

http://www.analogconsultants.com

 

[Fred Bartoli]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans le
message de news8cja1lun8mg2acevreeum6vim8f3i04ud@4ax.com...

On Fri, 10 Jun 2005 06:40:21 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Fri, 10 Jun 2005 19:35:39 +1200, Terry Given <my_name@ieee.org
wrote:


Ya gotta love it when that happens. I love that Gore Vidal quote - "It
is not enough to succeed, others must fail"

Cheers
Terry

The only problem is that you can't gloat and rub it in, it drives the
clients away.

So all I can do is laugh with the wife over a glass of wine ;-)


Right. You can prove that you're smarter than them, or you can get
repeat business, but not both.

Well, I once told a client that if he wanted the work to be done like this
and like that, he had to go to the competitors. I also told them that they
will fail like this and like that, which of course they didn't believe.

Guess who I saw coming back a year later?

Of course you have to be pretty sure of what you say.


--
Thanks,
Fred.

 

[Joerg]

Hello Fred,

Well, I once told a client that if he wanted the work to be done like this
and like that, he had to go to the competitors. I also told them that they
will fail like this and like that, which of course they didn't believe.

Guess who I saw coming back a year later?

Of course you have to be pretty sure of what you say.

Then there are the clients who think they don't need to spend the money
on you, trying it on their own or offshore and never coming out with a
product. I had a potential client do that until their financial backing
ran out a few years later. In consequence the company no longer exists.
Coulda, woulda, shoulda... the problem they had wouldn't have been all
that difficult to solve.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Spehro,

Just food for thought: It may also be possible to use a shortwave ISM
band in a common mode arrangement. 13.56MHz or something. Crystals are
cheap and widely available. This makes the FCC issues a lot easier.

Sometimes when faced with similar situations I just use a function
generator to pipe in a carrier and look how much comes out at the other
locations.

Regards, Joerg

http://www.analogconsultants.com

 

[John Larkin]

On Fri, 10 Jun 2005 23:40:57 +0200, "Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> a écrit dans le
message de news8cja1lun8mg2acevreeum6vim8f3i04ud@4ax.com...
On Fri, 10 Jun 2005 06:40:21 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Fri, 10 Jun 2005 19:35:39 +1200, Terry Given <my_name@ieee.org
wrote:


Ya gotta love it when that happens. I love that Gore Vidal quote - "It
is not enough to succeed, others must fail"

Cheers
Terry

The only problem is that you can't gloat and rub it in, it drives the
clients away.

So all I can do is laugh with the wife over a glass of wine ;-)


Right. You can prove that you're smarter than them, or you can get
repeat business, but not both.


Well, I once told a client that if he wanted the work to be done like this
and like that, he had to go to the competitors. I also told them that they
will fail like this and like that, which of course they didn't believe.

Guess who I saw coming back a year later?

OK, but some people might be too embarassed to come back.

Of course you have to be pretty sure of what you say.

I try to soften the blow with something like "I got lucky on that one,
I think Clyde said something that made me think of it" or some such,
even if Clyde is in fact a dimmish bulb. I try to be "on their team"
instead of the outsider smart-alec; I don't want the glory, just the
money.

I also like brainstorming meetings where ideas just happen without
really distinct authorship. I did this a couple of weeks ago at
P****&W******, and it sure seems to have worked.

There are people in this ng who brag about their ability to deliver
calibrated insults to their customers' intelligence, and further
complain about being unemployed.


John

 

[John Larkin]

On Fri, 10 Jun 2005 21:49:00 GMT, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Then there are the clients who think they don't need to spend the money
on you, trying it on their own or offshore and never coming out with a
product. I had a potential client do that until their financial backing
ran out a few years later. In consequence the company no longer exists.
Coulda, woulda, shoulda... the problem they had wouldn't have been all
that difficult to solve.

Yeah, I've had maybe three like that, and I'm eagerly looking forward
to #4 in the near future. My stock will be worthless, but at least
I'll get to dance on their grave.

John

 

[Fred Bloggs]

John Larkin wrote:

On Fri, 10 Jun 2005 10:44:01 GMT, Fred Bloggs <nospam@nospam.com
wrote:



Tony Williams wrote:

In article <42A83423.1040507@nospam.com>,
Fred Bloggs <nospam@nospam.com> wrote:



Tony Williams wrote:


Maybe think about transmitting the comms as a common-mode
voltage....etc.

That's one of three possibilities of selecting two of three
terminals for the signal transmission , but for some reason it
is forbidden for safety reasons............


Pity. Common-mode signalling would probably be the
easier to implement.



........Also, the current carrier method of inducing a signal via
transformer with secondary in series with line is also rejected-
probably too much bulk required there.


An inductor at each end of the line might be used to raise
the impedance at the carrier frequency. This would allow
capacitively-coupled differential signalling.

* L1 50A,60Hz * L2
+-----/////---+--------->--------+--/////----+
60Hz supply ----- | | ----- Load
+-----/////-------+----------+------/////----+
* | | | | *
C1=== | | ===C2
| | | |
Tx Rx

Perhaps look for inductors from switchers, in the range
20-50uH at 50Adc polarisation. Use Speff's 455KHz
carrier frequency.


Now that looks darn near perfect....


Except for needing four windings in series with the 50-amp circuit.
Those will be huge transformers and nasty connections.

Why not

| tx | | rx |
| | | |
+---/////---+ +---/////---+

+-----/////---+--------->--------+--/////----+
60Hz supply Load
+-----------------+----------+---------------+


where the trannies are 1-turn primaries, just cores slipped over the
insulated power conductors?

John

A clip-on toroid looks real good... It appears that the real reason for
most of the carrier communication stuff using differential Line-Neutral
drive is the convenience of driving the signal out the same cord that
powers the circuit- can't beat that. But someone is going to look none
too bright installing all these filter components and line breaks when
it sounds like all he needs is to pull a few bucks worth of cheap
twisted pair through the power conduit- he can do this with a low
voltage power circuit- but not a 120VAC type circuit.

 

[Rich Grise]

On Fri, 10 Jun 2005 21:49:00 +0000, Joerg wrote:

Hello Fred,

Well, I once told a client that if he wanted the work to be done like this
and like that, he had to go to the competitors. I also told them that they
will fail like this and like that, which of course they didn't believe.

Guess who I saw coming back a year later?

Of course you have to be pretty sure of what you say.

Then there are the clients who think they don't need to spend the money
on you, trying it on their own or offshore and never coming out with a
product. I had a potential client do that until their financial backing
ran out a few years later. In consequence the company no longer exists.
Coulda, woulda, shoulda... the problem they had wouldn't have been all
that difficult to solve.

Tell me about it! BTDT, YMMV, ISTR, IIKTWIIN, etc, etc, etc....

Cheers!
Rich

(and, of course, the big one: "I told you so!", which, as it turns
out, isn't that great of a money maker. )-; )

 

[Rich Grise]

On Fri, 10 Jun 2005 16:49:29 -0700, John Larkin wrote:
....

I don't want the glory, just the
money.
....

Master!

Teach me?

Thanks,
Rich

 

[Rich Grise]

On Fri, 10 Jun 2005 16:49:29 -0700, John Larkin wrote:
....

There are people in this ng who brag about their ability to deliver
calibrated insults to their customers' intelligence, and further
complain about being unemployed.
....

There are those who say, "The Customer is Always Right, Even When
He's Wrong!"

Right or wrong, the Customer is the one who puts food on my table.

Of course, it would be nice if the customers would follow our
advice such that they would continue to have money to put food
on our table with.

Like the Psycho son of the Psycho PHB said recently, "Let him
be proud."

Cheers!
Rich

 

[Rich Grise]

On Fri, 10 Jun 2005 08:37:06 -0700, John Larkin wrote:

On Fri, 10 Jun 2005 11:01:37 GMT, Fred Bloggs <nospam@nospam.com
John Larkin wrote:
On Thu, 09 Jun 2005 12:20:54 GMT, Fred Bloggs <nospam@nospam.com
Tony Williams wrote:
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:
I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and
I'd like to get 4800 or 9600 baud, but less would be acceptable.
There could be a couple hundred feet of wire, and I don't control
the source impedance.

Maybe think about transmitting the comms as a common-mode
voltage. The 24Vac system can be connected to Ground at
60Hz (or have stray-C to ground), just devise something
that makes that connection a high impedance at (and above)
the comms carrier frequency.

That's one of three possibilities of selecting two of three terminals
for the signal transmission , but for some reason it is forbidden for
safety reasons. Also, the current carrier method of inducing a signal
via transformer with secondary in series with line is also rejected-
probably too much bulk required there.

"Is also rejected"? Some sort of Royal decree?

Your series inductive coupling requires you to break the high power
utility circuit,

Speff said it was 'low voltage' which doesn't sound 'utility' to me; I
got the impression it might be some 'private' low-voltage system. And
you can slip a split-core ferrite over even an insulated conductor.

you do not need to break the circuit to install a shunt
source and the components do not have to be rated to withstand 10KA
surges and whatnots.

A low-mu core with a high-ratio winding, resonated on the primary,
clamped with a couple of zeners, won't have any spike problems. Making
a voltage connection into a utility line takes about as many
resonating and transient protection components.

ASK is the last kind of modulation anyone would
want to use.

Agree on that one. FSK or PSK makes more sense.

What, am I on _everybody's_ kill list? I said this on 8 June, to wit:
---------<quote>--------
On Wed, 08 Jun 2005 20:55:23 +0000, Rich Grise wrote:

On Wed, 08 Jun 2005 15:42:35 -0400, Spehro Pefhany wrote:
A little one-off (at the moment) G-job here:

I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and I'd
....
Any other suggestions?

Just OTTOMH - brute-force baseband (9600 HZ Manchester, DTMF, ?) through a
current transformer?

It's just I'm thinking "modulation", with a transmission line impedance of
0.2 - 1 ohm, 60 HZ "carrier" - or just superimpose your data stream, coded
at your leisure. What kind of noise and crap are we dealing with here?
---------<end quote>----------

How hard is it to separate a 9600 baud data stream from a 12VAC power
line frequency?

Or is it too simple?

Thanks,
Rich

 

[Rich Grise]

On Fri, 10 Jun 2005 19:35:50 +0000, Joerg wrote:

Some carrier current transmitters may go up to 50 Watts. That might overcome the
attenuation from a few line filters

With respect to mains applications there is also a legal limit and most
likely some further regs imposed by the utility.

From cost and EMI considerations, I was thinking more of <100mA at
100mV or so. ;-)

Some that I had seen just pound logic level onto the line, via a stiff
driver and a resonant circuit. The driver was often a plain old
transistor because it cost a few cents less than a driver. On the line
there may only be a volt or so left but that would be plenty if there
aren't too many EMI measures inside the loads near the receiving end.

The trouble with X10 is that it's an AM protocol and if the level at the
receiver drops below 100mV (which it easily does) reception becomes
flaky. FM should be much more robust. Just make sure no harmonics will
get you into regulatory trouble. That is another reason why a lower
frequency can be an advantage. Personally I wouldn't go to 455kHz.

ARGH! Is this an ego issue?

http://www.google.com/search?q=afsk+2295

It should be trivial! You've got, what, 30M of 12V power line?

AC couple AFSK through a current transformer, and pick it off on a
current transformer at the other end with a tone decoder.

Why is this turning into such an ordeal? Just because I joke around
a lot people think I'm incompetent electronically? I _do_ know stuff,
albeit at this point it's getting into an ego issue, and I have had
a couple of lubricative imbibations, but still! C'mon! How hard
does this have to be?

Thanks,
Rich

 

[Rich Grise]

On Fri, 10 Jun 2005 08:47:01 -0700, John Larkin wrote:

On Fri, 10 Jun 2005 10:44:01 GMT, Fred Bloggs <nospam@nospam.com
wrote:



Tony Williams wrote:
In article <42A83423.1040507@nospam.com>,
Fred Bloggs <nospam@nospam.com> wrote:


Tony Williams wrote:

Maybe think about transmitting the comms as a common-mode
voltage....etc.


That's one of three possibilities of selecting two of three
terminals for the signal transmission , but for some reason it
is forbidden for safety reasons............


Pity. Common-mode signalling would probably be the
easier to implement.


........Also, the current carrier method of inducing a signal via
transformer with secondary in series with line is also rejected-
probably too much bulk required there.


An inductor at each end of the line might be used to raise
the impedance at the carrier frequency. This would allow
capacitively-coupled differential signalling.

* L1 50A,60Hz * L2
+-----/////---+--------->--------+--/////----+
60Hz supply ----- | | ----- Load
+-----/////-------+----------+------/////----+
* | | | | *
C1=== | | ===C2
| | | |
Tx Rx

Perhaps look for inductors from switchers, in the range
20-50uH at 50Adc polarisation. Use Speff's 455KHz
carrier frequency.


Now that looks darn near perfect....

Except for needing four windings in series with the 50-amp circuit.
Those will be huge transformers and nasty connections.

Why not

| tx | | rx |
| | | |
+---/////---+ +---/////---+
+-----/////---+--------->--------+--/////----+
60Hz supply Load
+-----------------+----------+---------------+

where the trannies are 1-turn primaries, just cores slipped over the
insulated power conductors?

But I suggested this very thing last Wednesday! Waaaaaaahhhhh!

)-;
Rich

 

[Mike Monett]

Joerg wrote:

Hello Spehro,

Just food for thought: It may also be possible to use a shortwave ISM
band in a common mode arrangement. 13.56MHz or something. Crystals are
cheap and widely available. This makes the FCC issues a lot easier.

Sometimes when faced with similar situations I just use a function
generator to pipe in a carrier and look how much comes out at the other
locations.

Regards, Joerg

I like the wireless idea a lot more than carrier current. You can have a
proper bandpass I.F. with plenty of gain to handle signal levels down in the
microvolt region, and can go high enough in frequency to avoid most of the
man-made noise. This is difficult to do at low frequencies with carrier
current.

ISM is a good idea, but some bands are better than others. For example,
Diathermy machines may wipe out lower bands, such as 13MHz, and induction
heaters use other bands. These machines can have leads going between the
machine and the load, so there is plenty of opportunity for radiation
leakage.

The 2.45GHz band may be useless due to interference from microwave ovens.
However, there is a way to use this band without interference.

Since the magnetron only produces power when the anode reaches 4KV, there is
a brief interval at each zero crossing when no maggies anywhere are
conducting.

Just use this to transmit and receive data, and you have the band to
yourself

Mike Monett

 

[Mike Monett]

Joerg wrote:

Hello Mike,

From cost and EMI considerations, I was thinking more of <100mA at
100mV or so. ;-)

That might work if the transmitter and receiver share the same plug

LOL! That was a good one.

For X10, yes. For a good FM scheme you'd have lots of dB of head room
but it depends on the noise that rides along.

Regards, Joerg

Just plug an electric razor, vacuum cleaner or 3/8 inch drill in the same wall
socket as the receiver and verify the system still operates. Even better, run
them all at the same time

Mike Monett

 

[Fred Bloggs]

Joerg wrote:

Hello Spehro,

Just food for thought: It may also be possible to use a shortwave ISM
band in a common mode arrangement. 13.56MHz or something. Crystals are
cheap and widely available. This makes the FCC issues a lot easier.

Sometimes when faced with similar situations I just use a function
generator to pipe in a carrier and look how much comes out at the other
locations.

Regards, Joerg

http://www.analogconsultants.com

Hmmm- keep thinking and you will eventually discover Bluetooth ( or is
it BlueTooth)- a few billions of industrial serial<->Bluetooth modules
available for the express purpose of replacing or upgrading industrial
communications hard wire with wireless in a way that is transparent to
the control infrastructure.

 

[John Larkin]

On Sat, 11 Jun 2005 00:58:17 GMT, Fred Bloggs <nospam@nospam.com>
wrote:

A clip-on toroid looks real good... It appears that the real reason for
most of the carrier communication stuff using differential Line-Neutral
drive is the convenience of driving the signal out the same cord that
powers the circuit- can't beat that. But someone is going to look none
too bright installing all these filter components and line breaks when
it sounds like all he needs is to pull a few bucks worth of cheap
twisted pair through the power conduit

But that wrecks all the fun! How about blow-in fiber?

John

 

[Spehro Pefhany]

On Fri, 10 Jun 2005 21:31:38 -0400, the renowned Mike Monett
<no@spam.com> wrote:

Joerg wrote:

Hello Spehro,

Just food for thought: It may also be possible to use a shortwave ISM
band in a common mode arrangement. 13.56MHz or something. Crystals are
cheap and widely available. This makes the FCC issues a lot easier.

Sometimes when faced with similar situations I just use a function
generator to pipe in a carrier and look how much comes out at the other
locations.

Regards, Joerg

I like the wireless idea a lot more than carrier current. You can have a
proper bandpass I.F. with plenty of gain to handle signal levels down in the
microvolt region, and can go high enough in frequency to avoid most of the
man-made noise. This is difficult to do at low frequencies with carrier
current.

ISM is a good idea, but some bands are better than others. For example,
Diathermy machines may wipe out lower bands, such as 13MHz, and induction
heaters use other bands. These machines can have leads going between the
machine and the load, so there is plenty of opportunity for radiation
leakage.

The 2.45GHz band may be useless due to interference from microwave ovens.
However, there is a way to use this band without interference.

Since the magnetron only produces power when the anode reaches 4KV, there is
a brief interval at each zero crossing when no maggies anywhere are
conducting.

Just use this to transmit and receive data, and you have the band to
yourself

Mike Monett

Well, if I have to mess with 2.x GHz, I'll just slap a Zigbee or two
in there and be done with it.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Mike Monett]

Spehro Pefhany wrote:

[...]

Well, if I have to mess with 2.x GHz, I'll just slap a Zigbee or two
in there and be done with it.

Best regards,
Spehro Pefhany

LOL! Sometimes it pays to post. Thanks - I was not aware this product
existed.

Seems simple and attractive. Any reason you prefer to not use it?

Mike Monett