Thread: Eric Dollard
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Old 02-10-2016, 03:59 AM
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Two Modes. Conjugate wound…...

Some of Tesla’s patent drawings clearly show pairs of counter wound (conjugate) transmitting and receiving resonant transformers. Why is that? Three small 4.5 inch diameter experimental coils were constructed in order to conduct experiments to see if any significant effects could be observed between coils wound in opposite direction versus coils wound similarly. These 3 coils do not conform to professor Dollard’s proportions for proper resonant transformer design. They were sized for ease of construction, for winding on a small lathe and based on a series of previously built Extra coils. The coils are proportioned to be 1/4 wave resonant on the 160 meter Amateur Radio band so as to avail my Amateur license and transmitter exciters for these experiments. Two of the coils were wound in the standard clockwise direction as viewed from the bottom of the coil. One coil was wound counter clockwise. I use the term “standard clockwise direction” because it mimics the natural direction vines spiral here in the North Eastern United States. The term “coil” used here is equal to “Tesla Resonant Transformer”. The information presented in this post was gathered in early 2015, recently verified and is presented as a work in progress with many directions and questions to follow. But I have been told that the coyote sometimes is happy with half a bite.... and work based on professor Dollard’s teachings should not be held private. This is my opening offering.

From lab notes:

Coil description:
Three 4.5 inch diameter experimental coils wound around a form of nine - 5/16 inch diameter fiberglass rods held in place with fiberglass sheet end caps. The forms measure 6 inches tall. A five inch length is taken up by 102 turns of # 22 copper magnet wire and one top turn of # 14 bare copper. This makes up the secondary. The primary has 3 turns of 1/8 inch OD coax where the shield is used as the conductor. The form assembly was chucked in a lathe where the secondary was wound. Type “F” epoxy spray insulating varnish was applied to the secondary winding to lock it in place.

Initial Test:

Each secondary coil’s neutral (bottom end) was series fed against the lab earth connection with the 50 ohm output of a Kenwood TS50 mobil transmitter at around 10 watts to find the baseline resonance point. The transmitter was powered by a 12 volt battery, isolated from the AC mains and ground. Resonance was detected by sensing the peak electrostatic (dynamic) field with a 1 inch square copper sheet probe and by finding the peak earth current. Both the earth current and E field intensities track each other through the resonant finding frequency sweep. The “E” probe was located 30 inches out horizontally from the top of the secondary and was coax connected to a digital scope meter. Any closer and even this small 1 square inch probe would effect the resonant point of the system. Earth current was measured with a coarsely calibrated home brewed toroid current transformer installed at the earth connection. This provides a good reference, reading current flowing in and out of the earth at the 1.8 MHz resonant range. This earth ground consists of a 3/4 inch x 10 foot copper clad rod driven into the earth located in the center of a concrete slab floor of a 22 foot by 40 foot room. This rod is connected to four radial 3/8 inch galvanized steel cables embedded in the concrete leading off to the corners of the floor. These radial feeders are bonded to the steel reinforcing mesh in the concrete and are terminated in the corners of the floor with their own ground rod. An elevated capacity for the initial tests was made from a 5 inch diameter loop of # 14 bare copper, mounted 5 inches above the top of the secondary and connected to the top turn.

Coils #1 & 2 were wound clockwise (CW) and coil #3 was wound counterclockwise (CCW).

Coil # 1CW. Fo = 2351 kHz, E Probe = 181 mV, Earth current = .74 amps
Coil # 2CW. Fo = 2295 kHz, E Probe = 188 mV, Earth Current = .74 amps
Coil # 3CCW Fo= 2336 kHz, E Probe = 188 mV, Earth Current = .74 amps

Replace elevated capacity of coil #1CW with a 6 inch diameter toroid loop of .5 inch OD hardline, 5 inches above secondary. Drove secondary in series against ground through the neutral as above and then through the 3 turn primary with matching tuner in line.

Coil # 1CW neutral fed: Fo = 1858 kHz, E probe = 388 mV, Earth current = .5 amps
Driven with 3 turn primary: Fo = 1840 kHz, E Probe= 352mV Earth Current= .54 amps

It can be seen, comparing the previous observations that the larger elevated capacity lowered the resonant frequency nicely into the lower part of the 160 meter Amateur band and raised the E potential considerably while lowering the earth current.

Set up all 3 coils with .5 x 6 inch toroid loops as elevated capacities, 5 inch above top of secondary.

Measured input impedance at resonance, both of the secondary with its neutral fed against ground and with the primary fed directly with no added tank capacity for all 3 coils. An Autek VA1 analyzer was used for these tests.

Observations: (average readings)
Series feeding the secondary neutral against ground, the input impedance for coils 1,2 and 3 was approximately 48 ohms. Fo= 1854 kHz.
Feeding the 3 turn primary of coils 1,2 and 3: (secondary neutral grounded). Impedance was approximately 175 ohms. Fo = 1838 KHz.

It can be seen here that series feeding the secondary provides a good match for the 50 ohm output of the transmitter. The impedance of the primary winding is well within matching the transmitter output with a standard transmission line tuning apparatus.

Tuned all 3 Resonant transformers to 1850 kHz by adjusting the elevated capacity’s distance above the secondary while driving the primary with 50 watts from exciter transmitter. Set up 2 coils vertically on stands 6 feet apart, close enough for the fields to interplay. The two secondary neutrals were connected together. Power fed (50 watts) into coil #1’s primary while coil # 2’s primary had a 50 watt incandescent bulb attached. At resonance (1850kHz) energy was transferred from coil 1 to coil 2 through the single wire neutral connection and the bulb was brought to full brilliance with 50 watts input. Current flowing in the interconnecting neutral line was measured. E probe was 30 inches away from the driven coil #1. A four foot fluorescent tube was used to probe the field between the two coils. Coil #2 was substituted with the counterclockwise wound coil #3.

Coil #1CW feeding Coil # 2CW, Neutral line current = .58 amps, E probe = 364 mV
Coil #1CW feeding Coil # 3CCW, Neutral line current = .52 amps, E probe = 355 mV
In both cases the fluorescent tube showed a null at the center distance between the two coils being tested. This indicated the E fields around the two coils was out of phase. Probing the space between the coils with a pair of E probes made of equal size and lead lengths, feeding a dual channel scope meter confirmed the 180 degree out of phase condition of the fields. Not having the conjugate match made no difference delivering power to the receiving coil and it’s incandescent bulb. The winding direction made no difference in the phase relationship between each coil’s field with this arrangement.

Tests were done with the incandescent bulb out of the circuit. Removing the load of the bulb from the receiving coil increased both the E probe and current readings by about 30% in both cases. Again, clearly the fields around each coil were 180 degrees out of phase and the dark spot null could be found probing the space between the coils.

It was thought that in the previous observations, the series connected neutrals with only one primary being driven was forcing out of phase compliance of the receiving coil in some manner. This next test has the secondary neutrals connected as before with the current transformer in line at the mid point between the two coils. The two primaries were wired in parallel both in phase and out of phase. Again, a pair of E probes were set up on a wand, one probe on each channel of the scope meter and the space between the two coils was probed for phase relationships.


1. Both coil 1CW & 2CW primaries connected in parallel in phase: No nulls with fluorescent tube, a unified field present between the coils. E probes showed two in phase waveforms. Fo = 1919KHz. .3 amps neutral line current. E field was .348 volts.

2. Both coil 1CW & 2CW primaries in parallel out of phase: Null present with fluorescent tube, E probes showed two waveforms 180 degrees out of phase. Fo= 1838 KHz. Neutral line current =.35 amps. E field was .288 volts

Substitute the counterclockwise coil #3CCW for coil #2CW.

3. Both Coil #1CW & #3CCW primaries fed in parallel in phase: No null with fluorescent tube. E probes show two in phase waveforms. Fo= 1862 KHz The neutral line current was .85 amps. E probe .51 volts.

4. Both coil #1CW & #3CCW primaries fed in parallel but out of phase: Null present with fluorescent tube. E probes show two waveforms 180 degrees out of phase. Fo= 1840 KHz. Neutral line current .86 amps. E probe .432 volts.

Links to videos showing fluorescent tube probing the space between both in phase and out of phase conditions.
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