PRIMATIVE SPARK GAP TRANSMITTER


the Wanderling


BUILDING FROM SCRATCH A HOMEMADE

U.S. MILITARY SPECIAL OPS COVERT JUNGLE-RADIO SPARK GAP TRANSMITTER



A number of cross-border forays from surrounding areas were put into place requiring the use of a number of covert ground teams inserted into rather remote and primitive conditions. On the non-indigenous American side, each team member and their equipment was sheep dipped and all teams embedded with specially trained communication personnel, each heavily blanketed with security clearances, versed in Morse code and the non-conventional expertise to build from scratch and use, if necessary, easily disposable Spark-Gap Transmitters and QRP transmitters, along with foxhole radios and crystal set receivers, and of which too, all members were trained to travel light with no large tools or parts as well as eating indigenous foods, and leave no tracks.(see)

The quoted paragraph below comes from the main text of Spark Gap Transmitters, linked elsewhere on this page. The "me" referred to in the first few words of the opening sentence, as in "the Army sent me," alludes to me, the Wanderling:


"(The Army) sent me to a two week two part each hands-on workshop or seminar where, after classroom introduction to theory and application, we built and operated our own spark gap transmitters from stuff that could pretty much be just scrounged around for --- and made in the field without using any commercially available or already made tools. In other words, side cutters, screwdrivers and such weren't allowed, so we had to improvise. At the end of the workshop we were all supposed to end up with a viable operative spark gap transmitter, of which I did. Then as a group we shared what we each had done individually to improvise tools and how, that is, what we did, use, or came up with in lieu of screwdrivers, drills, or wire cutters --- or did we implement shortcuts or discover other options. Telegraph keys weren't provided either, so we had to make those from scratch too. Although ignition coils were acceptable, at the end of the seminar we were taught how to make our own induction coils from scratch, along with their application and use as well as learning about and building rudimentary at best, truly simple primitive devices other than traditional spark gap transmitters that could accomplish the same purpose, that is, junk from a jungle environment, a jungle with a history of being peopled over the centuries littered by a history of war."



AMAZING THAT SPAM CANS CAN STILL BE DUG UP, AND REAL TIN, TOO



What follows is how to build an operable low-powered spark gap transmitter basically of scrounged scraps and materials not unlike the ones we made in the Army. Now, any of you who may have been in the Army probably have heard the old saying that goes like, "There's the right way, the wrong way, and the Army way." When deployed into some foreign country and you and the life of the team depends on it there's no time for niceties. In the states when it come to what you can and cannot do when it comes to transmitting radio waves you may very well be regulated by the rules of the FCC. In so saying, anybody and everybody who falls under such auspices, I would expect to abide by those rules when finding themselves in a position to blanketed by them.

On the other hand, if one were to find them self stuck out in the middle of some remote jungle thousands of miles away from the the good old USA under combat or covert conditions other rules can sometimes overrule or permeate your survival, and quite frankly when it comes to the right way, wrong way, and Army way, the Army way takes, at least as far as your superiors are concerned and the completion of the mission, precedent. The Army has ways with just a little bit of messing around to take an otherwise nondescript low power spark gap transmitter and jack it up with a minor amount of screwing with it to turn it into a fairly powerful tool for radiating electromagnetic radiant energy, and other than the most obvious such as increasing the power output (battery) and wrapping the nail with additional wire coils, I'm just not going to reveal them. The homemade from scrap spark gap generator as used by the Army was for emergency purposes only anyway. Because of limited range the most they would be used for was to send a short distance signal to a more powerful "real" transmitter for relay and/or for the electronic "spark" to be picked up by ultra-sensitive satellite surveillance to pinpoint a location or short message.


For those of you unfamiliar with or don't know what the Federal Communications Commission (FCC) is, the FCC oversees all the regulations related to radio, TV, etc., in the US. Before the FCC there was the Federal Radio Commission (FRC) which oversaw radio communication from 1927 until 1934 when the FCC took over. The FRC was established by the Radio Act of 1927 which replaced the Radio Act of 1912. Prior to that the radio field was the Wild, Wild, West. Below is a click through list of free books in PDF about anything and everything you would ever want to know about wireless telegraphy, from building to operation, of which all are freely available on the net. Every one of them were written and published well before the forming of any sort of a formal commission to regulate everything, so everything presented is pretty much wild, wild, west.


DIAGRAM OF A PRIMATIVE ELECTRONIC WIRELESS SPARK TRANSMITER USING A "HOMEMADE" BUZZER:
 


                                          BUZZER
                                     (Generates Sparks
                                       & Radio Waves)

     !--->----->---->---->---->-------@  Sparking contact on top. (A Nail)
     !                              ~~ \~~   {~SPARKS~}
     !                                   \
     !                                     \    Moveable contact held up by 
     !                                       \    its own springiness and  
     !                                         \  Pulled down by the coil.
     !                                    !------ 
    KEY                                   !
    (Completes or breaks       Coil of 100-200 turns of
     the electric circuit)      INSULATED Wire Wrapped 
     !                           around an IRON nail
     !                                       !
     !---<----<---- BATTERY ---<----<-----<--!
            (Supplies the voltage)


----------
------------------KEY--------------------------------------------------BATTERY------------------------------------BUZZER



Pictured above, for our purposes here, is a graphic of the "buzzer" as so designated on the diagram and as so used in our spark gap transmitter construction endeavor. However, the buzzer itself had a much bigger role in the endeavor than implied. Most took it to be simply no more than a gizmo to replicate an audible Morse code sound for those so interested. In real life the buzzer is actually an electromagnet designed to "break" the electric circuit that activates it as soon as it is activated. As pictured the electric circuit is activated, set into motion, or completed by a "key," the key being no more than a push up and down switch that unless closed to complete the circuit disallows or interferes with the free flow of the electricity through the circuit. If there was no key and the circuit was wired clear though without a key the spark would continue repeating itself again and again, ad infinitum, until the power supply went dry.



The power supply, again for our purposes here, is made up of two 1.5 volt D cell batteries hooked together in parallel. As to how the power supply might run dry, in a brief overview, the following is provided by the source so cited:

Electrons will flow as long as there is an electric field to move them in. When you first connect a wire to the negative terminal of the battery, the electric field generated by all of those electrons stuck on the negative terminal will cause them to move into the wire. They will basically move to distribute the electrons evenly along the wire. This happens fast, the exact speed depending on the particular wire, but we're talking microseconds, even over 1km of wire.

Eventually the electrons reach the far end of the wire where they interact with whatever it is hooked up to. If it is the positive terminal of the battery, then there's a bunch of positively charged molecules that they can combine with to become neutral. This is basically always a desirable thing, from an energy perspective, so they do it really fast. Once those molecules are neutralized, the chemical reaction in the battery is knocked out of equilibrium, and it starts generating more electrons at the negative side and more positive ions on the positive side. It does so by depleting chemical energy. This opens the door for more electrons to flow through the wire, and the expected result occurs: a short circuit.(source)

As for the buzzer, making one, its construction, and how it works please see Footnote [1]



BOOKS:

The following books have been selected because all were written and published in the very early days of radio when radio and the transmission of electro-magnetic waves was young and things-telegraphy and radio were still being built and designed by hand to be used the same way in and by the radios of the same way. No capacitors, diodes, or transistors off the shelf. Since what is being dealt with here was handmade simple primitive spark gap transmitters under rudimentary conditions under the auspices of the Army and any need thereof the information within and presented by the books are perfect. Wished I had read them first.




  1. MAKING RADIO WAVES

  2. SIMPLE TRANSMITTER

  3. BUILDING A TRANSMITTER

  4. BUILDING A TRANSFORMER COIL

  5. TRANSMITTING AND RECEIVING A SIGNAL

  6. MAKING A HOMEMADE 14-CELL 9-VOLT WATER POWERED BATTERY


COPYRIGHT NOTICE: Several graphics included on this page have been provided through the graceful services of Prof. Tom Perera Ph. D. as so sourced below and are Copyright (c) 2013 by Prof. Tom Perera Ph. D. Although all the pictures and text are copyrighted in his works so provided, he states it is ok to use any of them for personal applications including public lectures, demonstrations, publications and websites as long as the www.w1tp.com Museum is mentioned.(source)

No compromised pictures, diagrams, photographs, specific dialog, or text of any kind regarding the special ops spark gap transmitter in whole or in part have been included in or made accessible through, by, on, or from this page, copyrighted, public domain, or otherwise.


VETERAN'S ZEN

FROM K.P. TO ENLIGHTENMENT: ONE G.I.'S PATH FOR ALLEVIATING STRESS,
DISSIPATING ALL THE THE BULLSHIT AND LAYING LOW THE FOG OF WAR


(please click any insignia)


WESTERN UNION STANDARD RADIO TELEGRAPH SIGNAL SET


MORSE CODE, HAND KEYS, AND DA VINCI


THE CODE MAKER, THE ZEN MAKER
SHANGRI-LA, SHAMBHALA, GYANGANJ, BUDDHISM AND ZEN

THE SAIGON TEA GIRL


THE DANCER
WIRETAPPING THE VIET CONG



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ENLIGHTENMENT

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EDGE


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THE WANDERLING

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As to the subject of donations, for those of you who may be interested in doing so as it applies to the gratefulness of my works, I invariably suggest any funds be directed toward THE WOUNDED WARRIOR PROJECT and/or THE AMERICAN RED CROSS.

















Footnote [1]



HOW TO BUILD A BUZZER

---------

The buzzer so shown and used in our primitive spark gap transmitter is actually a dumbed down induction coil in disguise and somewhat less powerful because of only the single wire coil wrap. The reason it has been presented the way it has is because it is supposed to be scraped together from parts found in the wild. Further down, unheralded and without major input it starts to sneak by as becoming somewhat more sophisticated and done so to continue to keep it simple but for you to squeeze more into it and out of it. Actually, in the field I used to carry a little rolled up kit with stuff I knew I would never find and would really need if I wanted or needed a powerful from the wild spark gap transmitter. As for the buzzer pictured, to make your own, wind about 100-200 turns of wire around an iron nail arranging it so that activating the electromagnet it pulls down on an iron-tin magnet-attracted armature which opens an electrical contact and breaks the circuit to the electromagnet. You can turn it into a much stronger more viable induction coil by adding a secondary coil as explained in Spark Gap Transmitters Part I, as pictured in the diagram below. Note the second coil wrap:



(please click image)

How the buzzer "works: " As soon as the circuit is broken, the spring tension of the armature returns it to it's original position and the circuit is made again. This cycle of break-the-circuit and make-the-circuit continues over-and-over making the armature vibrate or buzz for as long as a voltage is applied --- the voltage being applied only when the key is held down to complete the circuit to the buzzer. The electric contact makes sparks as it makes and breaks the circuit. The following operation explanation, with some minor editing for our purposes here, is from the Introduction to Radio Equipment, NAVPERS 10172, 1946, printed by the U.S. Government Printing Office, thus in the public domain:

Look at Figure [1] Switch Closed, below. The switch is in a closed position and the current is rising. The induced voltage is always in opposition to the voltage that created it. Thus, if the EMF of the battery is 10 volts and the induced EMF is 2 volts, the resulting EMF tending to cause the current to flow through the coil is:

10 - 2 = 8 volts.

After the current has reached a steady value, the induced voltage becomes zero, and the resulting EMF is:

10 - 0 = 10 volts.

As long as a steady current is maintained, no induced counter EMF is present, and the magnetic field remains constant.


---------

FIGURE [1] SWITCH CLOSED------------------------FIGURE [2] SWITCH OPEN


When the switch is suddenly opened as in Figure [2] Switch Open, the magnetic field collapses and induce a voltage in a direction opposite to the counter EMF, the same direction as the applied voltage. Hence, the induced EMF from the collapsing field added to the battery voltage will cause a SPARK to jump between the terminals of the switch.


-----
ABOVE GRAPHIC PROVIDED THROUGH THE GRACEFUL SERVICES OF PROGENY


For those of you concerned with the DC side of things inherent in the design use, the spark or disruptive discharge creating the radio interference does not in and of itself create radio waves. It excites resonant radio frequency oscillating electric currents in the conductors of the circuit. The conductors in turn radiate the energy in this oscillating current out as high frequency electromagnetic waves, i.e., radio waves, in every direction to a very great distance.


The following paragraph and list are found on Amateur Radio Stack Exchange so sourced, written by Niels Nielsen and Steve Richards respectively:

The spark gap's purpose is to very suddenly change the current in the LC circuit (above diagram, right) in of which the antenna is, in fact, directly connected. The sudden change produces a very strong inductive kick in that circuit, producing a suddenly-rising voltage. That sudden rise gets filtered by the capacitor and inductor, causing them to resonate at the transmitting frequency with an amplitude that exponentially decays as RF energy gets radiated out of the circuit and into space via the antenna. Careful choice of the circuit components and spark gap length then cause the spark breakdown to occur at a repetition rate in the audio frequency range, thus producing a wave train consisting of successive mHz oscillations that decay and get replaced by fresh oscillations at a rate of hundreds of Hz. the waveform is heard at the receiver as an amplitude-modulated carrier with significant sideband widths.