- May 4, 2019 at 4:50 pm #111052radio8zSenior Moderator
Total posts : 232
It has been fun to read some of the experiences of yesteryear posted in another thread (https://part15.org/forums/topic/knightkit-am-broadcaster-a-close-look-inside/) so here’s another adventure from then that some may want to try, or at least ponder.
Going back to about 1962, I had read about the prohibition of amateur radio activity during World War 2 during which some amateurs resorted to connecting an audio amplifier output to two stakes driven into the soil, sorta like what we now call “neutral injection” for carrier current with the major difference being that the energy injected into the soil was audio rather than RF. The intended receiver was a set of sensitive headphones connected to two conductive rods which were to be pushed into the soil and which would respond to the voltage gradient caused by the audio amplifier at the source site.
My neighbor was a former WWII bomber pilot and gave me a set of headphones which were so sensitive that just touching one of the phone pin tips would produce an audible hum from the energy induced from the power lines. Since I had a new 48 watt audio amplifier and super sensitive headphones I thought I would give this a try.
My parent’s home already had a very good first electrode being a buried copper water line connected to the main in front of our home. For the second electrode, I selected a site at the back edge of our property and planned my electrode installation. I dug a hole about 2 feet in diameter and three feet deep and carefully layered aluminum foil in a layer cake arrangement of foil, salt, and soil and connected the foil to a metal stake which protruded a few inches above the soil/foil filled hole. All was at the ready as I sought about 120 feet of wire to connect this buried electrode to the amplifier with the electrical return being the water main drop and using the headphones as a receiver with two probes to be stuck into the ground at various locations in the neighborhood to assess signal strength very much like driving around town with a good car radio to check Part 15 transmitter range as many of us have done.
Unbeknownst to me, I had placed my electrode in a utility easement and the gas company was about to install a new primary gas service line which soon resulted in them trenching directly through my electrode as if it was a surveyor’s stake. (I have to wonder what they thought when the aluminum foil shards were dredged to the surface but never approached them to ask about this.)
So, foiled again in another experiment, I abandoned the project and to this day wonder how well it would have worked. I returned to my boring Part 15 KnightKit powered attempt to play with communication technology.
Our neighbors usually observed without knowing the details of my many such experiments and I sometimes heard comments such as “strange child”. Wouldn’t trade a second of these memories for anything and hope you had a bit of fun imagining what it was like.
NeilMay 12, 2019 at 6:49 pm #111090BrooceParticipant
Total posts : 49
<p style=”text-align: left;”>When I was 6 or 7 years old I connected some wires to a big</p>
battery and hung them straight up in the air with some string.
Then I went to the other side of
the room and connected some long wires to a little motor. After I hung THOSE wires up in the air — I looked at the whole thing for a while.
Then I went over to my dad and asked him why the motor wasn’t
running. He had already started laughing before I got to him.
BrooceMay 12, 2019 at 8:28 pm #111093radio8zSenior Moderator
Total posts : 232
Nice story, Brooce.
What if you had installed hidden wires to feed the motor power, you would probably still be laughing about your dad’s reaction had this been the case. Such imagination and the drive to actually try an experiment is a valuable trait.
Related to such trickery, as a really young fella I had read about a thing called “Yehudi’s lamp” or something like this. It consisted of a coffee can filled with sand and had a flashlight bulb placed base up in the sand with only the globe of the bulb touching the sand, and the lamp would light without any apparent power connection.
The secret was to remove the base from another lamp and glue it to the top of the lamp so it would point upwards giving the illusion that the lamp had no connection and then to power the lamp via wires soldered to the actual bulb base which was buried beneath the sand along with hidden batteries. Fooled a lot of people with this one.
I tried another experiment which worked with no tricks, one which I had read about. I built a headband from cardboard and wrapped a couple of hundred turns of magnet wire around this form and wore it as a halo above the headphones mentioned in the O. P. I wound three or so turns of wire around the perimeter of the room forming a transformer primary and connected this loop to an audio amplifier output. My halo, serving as the secondary winding, picked up the audio by induction and it could be heard in the headphones. No worry about Part 15 or antennas, grounds, and such.
It was a lot of fun to try such things.
NeilMay 13, 2019 at 9:07 am #111094ThelegacyParticipant
Total posts : 273
I remember those sensitive earphones on the electronics kits you would find at Radio Shack. Now I wonder just how far that audio would have went under ground and if it went a mile or two it could be a way around part 15. The trick would be to transmit Stereo that way.
Now I had an experience with a cordless phone I could never figure out why this took place. We had two separate phone lines and I’d be talking on my Cobra cordless phone and Mom would be using a regular phone. As I walked around if I had any background Hiss I heard Mom talking and the other person she was talking to as well and so did my friends. When I picked up my regular phone or walked where there was no hiss I didn’t hear her or neither did my friends. I was thinking something in that cordless phone was acting like a telephone pick up coil you know the ones you’d put near your phone to record phone calls? I found by connecting the pickup coil to any sort of amplifier I could listen in on phone calls.
But I never could figure out why the cordless phone was picking up the other line and transmitting the audio over top of my own audio plugged into the base receiver. The only thing I could think of is the phone lines were using some sort of common ground.July 19, 2019 at 12:04 pm #112061
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