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Author Topic: A free AM Carrier-Current Coupler Unit? You might already just have one.  (Read 7192 times)

Offline ThaDood

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Ya know... A friend of mine struck on a subject that I've wanted to explore for a while now, a free Carrier-Current Coupling Unit for the AM Broadcast Band. And, you might just have one already. When a DSL MODEM is done with use, don't trash it, but cob it for parts, like that built-in coupler for Carrier-Current to the phone lines. You'd think that would be good for a few watts. And, not HOT inject, but Neutral inject. Hey... The price is right, and everyone usually just trashes these. Certainly, worth looking into. I have yet to try this myself, but had contemplated on the idea for a while now. So, if y'all out there got the time to open one of these units up and cob the coupler units, I'd like to hear the results.
“I am often asked how radio works. Well, you see, wire telegraphy
is like a very long cat. You yank his tail in New York and he
meows in Los Angeles. Do you understand this? Now, radio is
exactly the same, except that there is no cat.”
-Attributed to Albert Einstein, but I ripped it from the latest Splatter .PDF March 2025 issue.

Offline tybee

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Carrier-Current to the phone lines?
What exactly do you mean?

In any case, sounds intriguing.

Offline tybee

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Some key excerpts from https://www.blackbox.com/insights/blackbox-explains/inner/detail/networking/connectivity/what-is-a-dsl-modem


What is a DSL modem?
A DSL "modem" is a baseband modem (MOdulator/DEModulator) that delivers high-speed communication for short-distance interconnection or last-mile access. A DSL modem uses special coding techniques to get maximum throughput from the low bandwidth of voice-grade copper wire. At either end of the copper phone line (also known as "twisted copper pairs"), a DSL modem is installed. By adding ordinary telephone splitter boxes, the line can handle simultaneous voice connections.

Asymmetric DSL (ADSL)
..... provides asymmetric transmission over one pair of copper telephone wires, and it allows the telephone line to be used simultaneously for voice and data transmission.

Integrated DSL (IDSL)
... to deliver transmission speeds from 64 kbps up to 144 kbps. It allows for extended distances.. ... it is a dedicated service for data communications only.

Multi-rate symmetric DSL (MSDSL)
... operates at a variety of rates, ... to enable service providers to offer increased flexibility to their customers.

High-bit-rate DSL (HDSL)
High-bit-rate DSL is similar to SDSL and has symmetrical transmission capabilities. Most E1 lines installed today use this technology.

High-bit-rate DSL 2 (HDSL2)
.  ...uses only a single twisted copper pair. This is a distinct advantage in certain areas where unused copper pairs are becoming rare. HDSL2 is currently being developed as an industry standard.

Rate-Adaptive Asymmetric DSL (RADSL)
... rate is automatically adjusted to optimise the signal quality under the line condition.

Very high-bit-rate DSL (VDSL)
... very-high-bit-rate DSL, delivers high bandwidth over an existing single pair of copper wires. VDSL is the highest-speed technology in the XDSL family.
 

Offline ThaDood

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Hey Tybee... Interesting DSL INFO. However, no INFO upon what FREQ(s) are used to do it RF-wise. So, ever notice when you are trying to listen to an AM station, from like 1,000kHz to even near the 160M Amateur Band, and get an earful of digital hash on some FREQ's? Apparently, Medium Wave is where DSL is modulated upon. One of those FREQ's happened to be 1620kHz here. Now, Verizon tries to cram DSL to reach up to like 3 miles. They may have relay booster points as well to get even further. So, if DSL is trying to get that kind of usable range, via a Carrier-Current technique, then it would seem logical that the couplers in the trashed DSL MODEM's could make for some usable, free, Carrier-Current Couplers for our use. Thus, why I'm contemplating upon this idea. 
“I am often asked how radio works. Well, you see, wire telegraphy
is like a very long cat. You yank his tail in New York and he
meows in Los Angeles. Do you understand this? Now, radio is
exactly the same, except that there is no cat.”
-Attributed to Albert Einstein, but I ripped it from the latest Splatter .PDF March 2025 issue.

Offline tybee

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Quote
DSL (Digital Subscriber Line) uses specific frequency bands for data transmission and voice communication. Data transmission occurs at higher frequencies (25 kHz and above), while voice communication uses lower frequencies (4 kHz and below). This separation allows for both services to share the same copper phone line without interference.

That's what google ai told me.

... So, if DSL is trying to get that kind of usable range, via a Carrier-Current technique, then it would seem logical that the couplers in the trashed DSL MODEM's could make for some usable, free, Carrier-Current Couplers for our use. Thus, why I'm contemplating upon this idea.

I think the idea sounds intriguing as hell, it would be a super cool re-use of the modems, there must be thousands of old used ones out there that could be picked up for pennies
« Last Edit: May 29, 2025, 1941 UTC by tybee »

Offline ThaDood

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https://www.edn.com/teardown-inside-a-dsl-gateway/  Ya know, ya look for tear-downs of DSL MODEM's, and everyone that has done so, and taken PIC's & VID's, are more interested in the IC's. However, what we are interested in, for our Carrier-Current purposes, is the built-in coupling unit. That link is more promising. From the green RJ-11 connector, follow that to the square block marked MOC. That, appears to be the coupler. Now, if we can get the pin-out INFO on that, this maybe our freebie coupler, as well as those coupling mylar CAP's that I see in there. Hmmmmmmmmmmmm... Me thinks me getting warmer?
“I am often asked how radio works. Well, you see, wire telegraphy
is like a very long cat. You yank his tail in New York and he
meows in Los Angeles. Do you understand this? Now, radio is
exactly the same, except that there is no cat.”
-Attributed to Albert Einstein, but I ripped it from the latest Splatter .PDF March 2025 issue.

Offline tybee

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Ever look at this? Says no coupler is needed. Excerpts below

https://k6prk.k6fb.com/CARRIER%20CURRENT%20AM%20TRANSMITTER.HTM

This transmitter makes use of the "neutral feed" system which may extend range over the typical "hot feed" method in certain situations and in any case will reduce or even eliminate the hum which typically plagues carrier current systems using the latter means of coupling to the powerlines. No coupler is needed with this unit; since the injection of RF into the neutral wire is internal, the unit simply need be plugged into an ordinary outlet. ... .. ... This transmitter's final tank values as shown above were designed for the middle of the AM broadcast band (~800-1200 kHz) but can be changed to any desired portion of the band, by simply increasing the number of turns on L1 ....

  .... When moving the unit from one outlet or branch circuit to another, retuning of L1 may be necessary. Also, if
 still is not satisfactory, it may be that your power system neutrals are not continuous throughout the entire grid or area.... ....

If it is desired to make this transmitter a "hot feed" unit instead of a neutral feed, simply unground the cold (grounded) end of L2 and feed via a .01 uF, 2 kV ceramic disc capacitor to the hot 117 v wire in the transmitter between the fuse and RFC3. No other changes need be made. These coupling capacitor values are not "etched in stone" and may be changed to tune out reactance in the lines if found to be necessary (in fact experimentation here is encouraged). ..


At the same link is a ....


A Universal Line Coupler For Carrier Current Use (Both "Hot" and "Neutral" Feed Methods)

Because of the great demand for a coupler design which will serve all methods of feeding AM broadcast energy into AC power circuits, a configuration is presented here which is felt to be about as "universal" as one can get. This ......


But I guess that's getting away from the topic of a free coupler by repurposing existing devices.
« Last Edit: July 09, 2025, 2120 UTC by tybee »

Offline tybee

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https://www.edn.com/teardown-inside-a-dsl-gateway/  Ya know, ya look for tear-downs of DSL MODEM's, and everyone that has done so, and taken PIC's & VID's, are more interested in the IC's. However, what we are interested in, for our Carrier-Current purposes, is the built-in coupling unit. That link is more promising. From the green RJ-11 connector, follow that to the square block marked MOC. That, appears to be the coupler. Now, if we can get the pin-out INFO on that, this maybe our freebie coupler, as well as those coupling mylar CAP's that I see in there. Hmmmmmmmmmmmm... Me thinks me getting warmer?

To be honest I'm pretty confused about what the guy in the article accomplished, or if he accomplished anything. At the same time I'm also confused over your exploration of how the DSL modem parts can be utilized for AM carrier current coupler.

I dont know much of anything about cobbling together electronic components from scratch or from repurposed parts, but I wonder why a carrier current coupler should be so complicated to make when the greatest majority of the carrier current stations over the last 80+ years had been assembled and put in operation by young inexperienced college students.

Is there really something so complicated about a coupler that the average Joe is unable to construct one himself?

I feel like I'm missing something here. I mean, how complicated can this box be? (LPBs TC2 coupler):


blogs.telosalliance.com/lab-carrier-current-am-transmitter

"The T2C matched the 50-ohm output of the transmitter to the (usually) much lower impedance of the power line, and also isolated the RF output from the AC line. .... The output of the T2C was usually connected to all phases of a building's AC service through a 4-prong plug and mating socket connected to the main breaker panel. 3-amp fast blow fuses provided the last line of defense."[/i]

If I'm missing your point, then I should be excused because I'm quite confused.
« Last Edit: July 12, 2025, 0413 UTC by tybee »

Offline ThaDood

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Well, yeah... You could indeed reverse-engineer a tried & true coupler from LPB and Radio Systems. And, what I like about that 2W AM C-C tube system is that all values are included, no real guess & calculate work. (NICE!!!) Ernie Wilson's book was nice about that as well. I was simply looking for a simpler, safe, plug & play alternative. Thus, why I came up with this,  https://archive.org/details/ye-poor-mans-am-carrier-current-coupler-10-5-2024-experimental    If you find more alternatives, that's even better.
“I am often asked how radio works. Well, you see, wire telegraphy
is like a very long cat. You yank his tail in New York and he
meows in Los Angeles. Do you understand this? Now, radio is
exactly the same, except that there is no cat.”
-Attributed to Albert Einstein, but I ripped it from the latest Splatter .PDF March 2025 issue.

 

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