YOUR OLD HORN SPEAKER IS LISTENING

BY Newcomb

Yes, you can talk to your speaker! – Sitting on display, disconnected, its diaphragm is still following the vibrations of your voice. -It always has!

Any collector with more than one horn, can connect two to each other and without power, battery, amplifier, transformer or switching can intercom; upstairs-downstairs or house - garage. Use most any kind of wire, as far as you like, (even for several miles.)

Many collectors do not realize that the same efficient horn design that couples the resilience of the diaphragm to the density of the air, also works in reverse. Instead of audio power being connected to the voice coil. The coil generates an audio power output. This is at a frequency and intensity that matches the vibrations of your own throat: It is because, you have moved the voice coil in its permanent magnetic field. The speaker is also a dynamic microphone as well as a magnetic receiver!

Seventy years ago, we were high school boys. My friend Arthur, lived a ½ country mile away. We used one wire, (+ ground, ) of a neighbor’s barbed wire fence. We had duplex, un-switched conversations, powered only by our own voices. The sound level was powerful enough to cross a quiet room.

This was at a time when real, BELL telephones were still using local battery and a hand -cranked magneto. Ten years later during the second war, I saw our Army Signal Corps using SOUND POWERED PHONES. An armored version of our own experiment.

Our horns worked so well that we left them in place and our two families used them as well.

There is no ringer explained here. If needed, any buzz or whistle sound into the horn will do. You can use an acoustic sound or an electronic sound coupled to the line. The two speakers will respond to it.

Note: These were permanent magnet horns. Those requiring a field supply were not suitable. Most voice coils were high impedance compared to to-days low ohm coils. This is why line loss isn’t a problem; and why matching transformers aren’t needed.

We extended our telephone line for about three miles and were joined by several other boys. Country roads were crossed by running wire underneath the road in culverts.

We began with two wires, batteries and homemade tramsmitters and receivers. We experimented without batteries and also found that one wire was enough.

We were using salvage, bare, iron, wire from abandoned vineyards.

This wire is not suitable for antennae.

Now we see children, playing house in the back yard with real, handset telephones, with touch tone dialing!

We were early collectors too. TRF receivers at 2nd hand furniture stores cost five to seven dollars, including the speakers and tubes. Speakers might be 75 cents or a dollar. Most of our insulated wire came from the primary of T Ford ignition coils. Our ‘A’ batteries were those car batteries exchanged at Western Auto for 50 cents! We chose those with the best spark when shorted with a wire! I have only a hand full of parts from those days.

TRY IT, -------- Connect your horns --------- they are already ‘on’.

A complete telephone Transmitter, receiver and ringer, in one piece.