In Post # 3 in this thread ABMedia1 tells us how he is doing it.
"the carrier current fm transmitter i have always used were mp3 car transmitters real cheap you as can get, the antenna is inside the 12 volt hookup and the end of the inside antenna touching the tip of the 12 volt hookup and the transmitter and internal antenna is sent through the car ac to wall adapter, and couples and hooks up at the wall plugin under the studio desk and is sent through the power lines throught the neighborhood and several blocks around it (the blocks here are very short). serves about 40-120 households depending on the conditions outside and serves anywhere from 120-360 people inside the coverage area."
It would be easy to draw a diagram from this information.
Ok.. So he is using a car-lighter plug to house converter? Or something else? Is it possible to do this with, say, a Ramsey fm25 or broadcast vision bv2001.
As fascinating as FMCC is, based on ABMedia1's results, I am not personally going to try it.
The only way we'll learn more about it is if somebody does a few experiments.
I just need to know what to do 🙂
I have a stack of Broadcast Vision BV2001 FM transmitters here, one has a broken antenna.. I'd love to know how to inject the RF into the power line...
Using the description of an FM Carrier Current System provided, let us attempt to reverse engineer and come up with a workable schematic. Let's take it line by line:
"the carrier current fm transmitter i have always used were mp3 car transmitters real cheap you as can get,"
We do not know if all MP3 car transmitters are made the same, so it would help to know a specific model number.
"the antenna is inside the 12 volt hookup"
The 12Volt hookup, we guess, is the power that makes the mp3 car transmitter turn on, but it is not said whether this voltage comes from a power supply or from an auto-cigarette-lighter-eliminator, and we are not certain of the way in which the transmitters antenna is inside the 12Volt hookup, is it factory wired that way, or is it a user modification? Perhaps we mean "RF Output" and not "antenna?"
"and the end of the inside antenna touching the tip of the 12 volt hookup"
We wonder if "inside antenna" means "the antenna inside the 12Volt hookup" or "the antenna inside the house." We do not have a description of the inside antenna, its length, is it vertical?
"and the transmitter and internal antenna is sent through the car ac to wall adapter,"
Interesting that both the transmitter and internal antenna are sent through the car AC-to-wall adapter... but I think it means the RF output of the transmitter is connected at the tip of the 12Volt supply point.
"and couples and hooks up at the wall plugin under the studio desk and is sent through the power lines throught the neighborhood and several blocks around it (the blocks here are very short). serves about 40-120 households depending on the conditions outside and serves anywhere from 120-360 people inside the coverage area."
We presume the transmitter is in fact receiving its 12V from the wall-adapter, and the negative side of the voltage supply is the transmitter ground.
We may have deduced our way into something, unless we read it the wrong way.
Can you think of a different way of interpreting it?
In a mental excercise I just imagined putting my Scosche car FM transmitter into this situation, and it would take a modification to do it.
I looked into the Scosche when it was new a year ago and saw that the RF Output was connected right to the shield of the audio wire, and the audio cable being 6-inches long, I unsoldered the RF Output and added a 6-inch independent antenna, and the transmitter has about the same output as the C.Crane cerified FM transmitter as seen on a spectrum analyzer.
Would I take the risk of hooking the RF Output of the Scosche directly to the DC positive? Not until checking the capacitor in the output circuit to make sure it was appropriate to such a connection, yet at the same time the risk would probably be minimal because the RF Output transistor is no doubt already getting DC+ for its operation, and the "tip of the positive supply" is probably not going to hurt anything.
It would be useful to have a model number and schematic for the particular wall-to-cigarette-adapter used by ABMedia1, because perhaps it has unique features not found in other types of power supplies.
Ok I tried the following:
Transmitter: BroadcastVision BV2001 FM Transmitter
"Pigtail": Standard 3 prong computer power cable cut to about 9"
In all 3 tests, I removed the telescoping whip antenna from the transmitter, and replaced it with a like length wire. In test 3 I added a second cable to ground for the bottom half of a dipole.
Test 1: wrap antenna wire around the length of the pigtail, plug pigtail into circuit leg that goes from outlet to breaker box and has nothing else on the line.
Result: I could head the signal about a half a block away (maybe 400 feet)
Test 2: wrap antenna wire around the pigtail, connecting the end of the antenna wire to the neutral line, and then plug into the outlet.
Result: Slightly better, I could get the signal along the power line, but not very far, still less than a block, about 800 feet.
Test 3: All out terrestrial free radiate 🙂 Just for grins. dipole using a set of rabbit ears and a balun. Antenna side to the top and ground to the bottom pole. Dipole at ground level (I was not gonna mount it high for this test, only to have to pull it back down)
Result: About a block and a half. Since the antenna was in the middle of my garage, there were a few blind spots around the area, but this was just to make sure the transmitter was actually capable of working correctly. Clearly, it is 🙂
Still no real carrier current love though.. sad.
I think your test was worthwhile, mir.
If I understood your report, you found that CCFM does about as good as an FM transmitter with an indoor antenna.
That's not a bad thing, it means there is an alternative to using an antenna...
But here's the bigger thing you might not have thought about...
Carrier Current carries a radio signal right through people's walls and into their houses, something an antenna does not do.
AND, with the simple method you tried, maybe there are tweaks and improvements that would increase the results!
You have raised my belief that SOMETHING can be done with CCFM!
Excellent!
But here's the bigger thing you might not have thought about...
Carrier Current carries a radio signal right through people's walls and into their houses, something an antenna does not do.
Ah - I had thought about it, and thought it would be cool to see.. I have some friends that live around the corner from me mon-fri, so when they come back to town, I'll ask if I can test at thier home.
AND, with the simple method you tried, maybe there are tweaks and improvements that would increase the results!
I am hoping someone provides me with some additional stuff to test 🙂
You have raised my belief that SOMETHING can be done with CCFM!
GOOD! Maybe if ABMedia1 can share model numbers/parts/etc, we can couple that (pun intended) with the higher powered, slightly better constructed FM transmitters and get some CCFM awesomeness rolling here.
My current test (.. this time, no pun intended) is sticking one of my BV FM transmitters, with its builtin antenna, on my roof.
So; im not giving up on this... I want to try the same transmitter with an amp on it.
Problem: I am not an RF engineer, nor do I have any sort of electronics aptitude other than following directions. So I need to solicit your help:
http://electronics-diy.com/1W_Universal_RF_Amplifier.php
If I wanted to build this for 104.1 on the FM dial (which is the only clear channel here, other than the 100watt pirate in berkeley), what would those coils' dimentions, number of winds, etc look like? "metal loops" is tha answer my 10 year gave me...
With your positive attitude for learning about radio your electronic aptitude is increasing, mir.
The coils L1 and L2 can be made just as your 10-year old says, by looping the appropriate number of turns around a 1/4"-diameter rod (a round pencil) using # 16 enameled wire. Once the coil is formed you remove the rod and the coil holds itself together.
Very gently scratch the enamel off the ends of the wire to allow soldering the wire, using a knife or other flat edged metal tool.
The inductor RFC, once calculated based on frequency, can probably be purchased from stock as the 1000uF inductors are very common and much used.
Once Part 15 gets in the blood not even a transfusion will get it out.
Here's a link to a site which I have used many times for inductor design. It looks complicated but all you have to enter is the inductance and wire gauge. I suggest 22 to 28 gauge so it is easy to form but you can use other sizes.
You can change the diameter, length, etc. to fit your needs. I ran 1.5 uH just as an example and it came back with about 15 turns and less than an inch long.
For these small inductances it doesn't make sense to buy when making your own is simple.
http://www.k7mem.com/Electronic_Notebook/inductors/coildsgn.html
Neil
you guys are awesome - thank you!