Pretest

Tb test the circuit out, temporarily and quickly con­nect a 12 VDC source of 1 amp to the input power leads, and note a current draw of around.3 to.5 amps. Touch the output lead with an insulated metal tool and note a small arc of [3]U to Чг inches. Do not operate for more than several seconds as Ql will overheat because it requires mounting to the base section for heat sinking. You may want to verify the wave shape on the collector of Ql, using a scope. It should resemble that shown in Figure 16-2.

Mechanical Rssembly

Assembling the parts is done by following these steps:

everything before actually drilling. Fold down the corner sections of the base to form the legs as shown in Figure 16-4.

2. Fabricate the bracket BK1 from a piece of formable plastic that is З X 1 V« X.063 inches. Fold a ‘/2-inch lip for mounting to the base section. Note the clearance hole for SW2. Position as shown, abutting to the rear of the assembly board. This will provide a stable mounting scheme.

3. Finally, assemble as shown in Figure 16-4. Secure the assembly board to the bracket using a plastic tie wrap. Ground the base sec­tion with a short piece of bus wire under SW2 and attach the wire to the P2 line on the board.

4. Fabricate the shroud tube from a piece of clear 10- X 174-inch OD plastic tubing. This piece slips over the assembly and provides enclosure protection while allowing visibility of the circuitry. This is an obvious asset when making a science project presentation. Note you will have to file slots or grooves at the bottom to allow airflow and to clear screw SW2.

Test and Function Selection

From Fig. 16-3

Pretest

grounding screw Figure 1Б-Ч Mechanical assembly

Connect a 12 to 14 VDC source of 1 to 2 amps, and test it by touching the output with the end of a fluo­rescent tube, noting a moderate bright glowing. Study the following data to decidc the experiments you wish to pursue. The unit can be operated from any 12- to 14-volt battery pack that can supply a current of 1 to 2 amps or more.

It is important, where noted, that the unit be earth grounded with a separate grounding connection to a known, grounded object. A wall adapter, when used, will require a separate grounding wire for proper operation as the output circuitry is usually isolated

from the primary plug side, as there is no third wire grounding pin. The screw of a receptacle plate can be used for this external connection, as is noted on the drawings. When using a converter, automatic ground­ing is usually via ihe third prong on the power plug, which is the same as the negative lead output (see Figure 16-4). Experimenting with ions will require assembly of the magnifier retrofit as shown in Figure 16-10.

Experiments and Applications Using Plasma

• Radiated power Energize a light without

any connections (sec Figure 16-5).

Radiated Power Project

Clear plastic should be removed for access io output It is necessary to prevent accidental contact that can cause annoying but not dangerous shocks.

Shape a 10" length of #14 bus lead or 1/16" brass rod and shape as shown wilh a loop lo fit around the screw for securing in place. This serves as a small energy radiator.

Obtain a gas discharge lamp such as a piece of neon or use the test neon lamp in the kit and, holding one of Ihe leads, bring it near ihe radiator, noling rt glowing up to a foot or so from the unit. Try with a larger fluorescent tube

Gas Tube Energy Supply

Touch one end of a household fluorescent tube to the output radiator and note lamp glowing wilh only the single connection. This demonstrates the high – frequency ground current flowing via the electrical capacity of the discharge tube.

Pyrotech Display

Obtain some steel wool and attach a small tuft to the oulput lead. Draw an arc with a grounded object and note strands brightly burning. Experienced personnel may wish to add certain oxidizing chemicals to greaily enhance this effect USE CAUTION.

– Air circulation gap

Pretest

Copyright 10/97

Connect this lead to Ihe socket plata screw of Ihe AC receptacle.

Fi g и re 16-5 Set up for radiated power

The ground lead is necessary for proper operalion of this project as capecitive ground currents are produced.

Pretest

Figure 16- б Jacob’s ladder project

Gas discharge power supply Energize color­ful neon and other gas-filled tubes (see Figure 16-5).

Electrical pyrotechnic display Burn up a piece of steel wool in a shower of sparks (see Figure 16-5).

Jacob’s ladder Build the popular traveling plasma arc machine seen in Frankenstein movies (see Figure 16-6).

Build au effective deodorizing machine It

actually produces fresh air (see Figure 16-7).

Magic electric man Energize a fluorescent tube by the touch of your hand (see Figure 16-8).

Plasma etching Use an electrical arc to cre­ate intricate designs in wood and plastic (see Figure 16-9).

Experiments and Applications Using Plasma

Circuit Theory

Figure 16- 2 shows transistor Ql connected as a free – running flyback oscillator with a resonant frequency determined by capacitor CX and the short-circuil pri­mary inductance (LP) of transformer Tl. The leakage inductance of Tl must be high as it is where the inductive energy is stored when Ql is biased on. The current now ramps up as a function of і = ET/L. Energy is equal to W = Li2/2.

Circuit operation commences when 12 VDC is applied and resistor R2 biases Ql on, and the current now flows through the primary of Tl, inducing a high voltage into the secondary winding. Oscillation is maintained by the base of Ql being controlled by the feedback voltage from the feedback winding on Tl. The feedback current is limiled by resistor R2. Capacitor CX aids in speeding up ihe turnoff time of Ql. Resislor R3 and capacitor C5 form a filter to pre­vent self-oscillation at the resonant frequency of the secondary ofTl.

Construction

To begin the project, follow ihese steps:

1. Lay out and identify all the parts and pieces. Verify them with the parts list, and separate the resistors as they have a color code to determine their value. Colors are noted on the parts list.

2. Obtain the available PCB as shown in Figure 16-3 or fabricate a piece ol perforated circuit board (perf) to match the PCB (PC) as laid

Experiments and Applications Using Plasma

Experiments and Applications Using Plasma

drawing as these indicate connection runs on the underside of the assembly board.

4. Attach three 6-inch #22-20 leads as shown for input power (Pi and P2) and external ground­ing. Attach a short piece of bus wire for grounding of the base section. Leads are routed through the BUI bushing and are twisted in the final assembly steps. Attach pieces of bus wire to the output connections (P3 and P4) and shape them to fit around the screws as shown.

5. Double-check the accuracy of the wiring and the quality of the solder joints. Avoid wire bridges, shorts, and any close proximity to other circuit components. If a wire bridge is necessary, sleeve some insulation onto the lead to avoid any potential shorts.

out. Note that the size of the PC board is 34i – x P/e-inches and contains the silk screening that shows the positioning of the mounted parts. Note that the Ql transistor must be mounted so that it is flush with its mounting surface at a right angle. This step is important for proper heat sinking and mechanically sta­bility.

3. If you are building from a perforated board, insert components starting in the lower left – hand corner. Pay attention to the polarity of the capacitors with polarity signs, as well as all the semiconductors.

Route the leads of the components as shown and solder as you go, cutting away unused wires. Attempt to use certain leads as the wire runs. Follow the dashed lines on the assembly

Figure 16- 2 Tesla plasma and ion schematic

Experiments and Applications Using Plasma

Note thal C6,7 are in в different location than that indicated by the screening on the printed circuit board

Fi g и re 16-3 Assembly board showing part identification

Circuit Theory

Figure 15-2 shows a high DC voltage being produced by a blocking oscillator circuit consisting of a trans­former (Tl) being switched on and off by a transistor (Ql).The current through the primary winding (I) rises as a function of Et/L (when Q1 is on), where E is the applied voltage, in this case 12 volts-direct cur­rent (VDC), and L is the primary inductance of Tl. This rise in current induces a voltage in the feedback winding further holding Ql on, due to supplying the base current through resistor R2 and the speed-up capacitor C2. When the core of Tl saturates because of a high primary DC current, the induced base volt­age goes to zero, turning off Ql. This results in a reverse voltage induced in the secondary forward – biasing diode (Dl) and charging capacitors (C3 and C4). When the charging capacitor reaches the trigger voltage of the SIDAC silicon switch (around 300 volts), it now turns on, dumping the energy stored in the capacitor into the primaries of pulse transformers (T2 and T3). This energy causes a rapid rise in the current “forward inducing the high-voltage output pulses required for the lightning display.

You will note that two pulse transformers are con­nected out of phase (reversed connected) relative to one another. This approach generates twice the out­put of what is possible from one transformer, now being in excess of 50,000 volts. You will note switch SI controls the primary power. Switch S2 selects the display texture. The base of Ql is the control port for the output of current sink Q2, which is controlled by switch S3.

Construction Steps

To begin the project, follow these steps:

1. Identify all parts and pieces and verify them with the bill of materials.

2. Insert the components, starting from one end of the perforated circuit board, and follow the locations shown in Figure 15-3, using the indi­vidual holes as a guide. Use the leads of the actual components as the connection runs.

which are indicated by the dashed lines. It is a good idea to trial-fit the larger parts before actually starting to solder.

Always avoid bare wire bridges, messy solder joints, and potential solder shorts. Also check for cold or loose solder joints.

Pay attention to the polarity of the capacitors with polarity signs and all the semiconductors. The transformer position is determined using an ohmmeter as instructed in Figure 15-3 . Note the SIDAC may have two or three pins. Only the outer ones are used and may con­nect in either way, as the part is not polarized.

3. Cut, strip, and tin the wire leads for connect­ing to SI, S2, and S3 and solder them. These leads should be 4 to 5 inches long.

4. Fabricate the plate section from a 43A X 2’Aj X.06 piece of plastic. This is the base plate for mounting and gluing the T2 and T3 pulse

coi Is/transformers.

5. Prewire T2 and T3, as shown in Figure 15-3, at the separation distance of 2 inches. Use short pieces of vinyl wire to extend these leads. Splice in 5-inch leads for interconnecting to the board.

6. Carefully position the wired pulse coil assem­bly to the plastic plate and secure it with sili­con rubber cement (a room temperature vulcanizing [RTV] adhesive). Clamp it in place to hold it in position as the cement sets. It is important to keep these coils straight for aesthetics.

7. Attach the discharge electrode wires using the wire nuts. You may solder these wires but must use care as excessive heat can internally damage T2 and T3.

8. Preconnect the pulse coil assembly to the board as shown. Connect the wall adapter using the wire nuts, observing proper polarity.

Electrical Pretest

Го test the project’s wiring, follow these steps:

1. Separate the ends of the discharge wires to approximately 2 inches. Preset the trimmer

Circuit Theory

Circuit Theory

Figure 15-2 Testa lightning generator schematic

pots to midrange and the slider switches SI and S3 to “off.”

2. Turn on SI and note a discharge occurring between the pulse coils. Change the position of the toggle switch S2 and note the discharge texture changing. Identify the switch position for heavy or light spark display.

3. Turn on S3 and note the display cycling on and off at an approximate rate of 100 seconds on and 100 seconds off. These times are inde­pendently variable over a wide range. Our suggested setting is 100 seconds on and 100

Circuit Theory

Final Assembly

For the final assembly, follow these steps:

1. Fabricate the enclosure from a 6’/4 – X 5’A – X.06-inch piece of plastic, as shown in Figure 15-4.

seconds off. Тіїe device can be left on continu­ously with these low-duiy cycle sellings.

Circuit Theory

Figure 15-3 Assembly hoard

Circuit Theory

Figure 15-4 Final assembly

2. Glue the pulse coil assembly, followed by the assembly board. Mount the controls and dress the wire leads for a neat-appearing assembly.

You can use a clear or colored piece for this part. Fabricate holes forT2 and T3. observing the proper alignment with the glued plate assembly as in the prior step. Fabricate the remaining holes for switches, power leads, and trimpot access holes.

3. Verify the operation and preset controls for the desired spark display and cyclic timing.

Table 15-1 Tesla 2-inch spark coil parts

Ref. # Qty. Description DB#

Rl 4.7K, !/4~watt carbon film resistor (yel-pur-red)

R2,8 2 470-ohm, V«-watt carbon film resistor (yel-pur-br)

R3 27-ohm, ‘/4-watt carbon film resistor (red-pur-blk)

R4.6 2 1M trimmer resistor vertical mount

R5,7 2 10K. ‘/4-watt carbon film resistor (br-blk-or)

C5 100 mfd, 25-volt electrolytic capacitor vertical mount

C6 220 mfd, 25-volt electrolytic capacitor, vertical mount

C7 .01 mfd, 50-volt disk ceramic capacitor

Cl 10 mfd, 25-volt electrolytic capacitor, vertical mount

C2 .047 mfd, 50-volt polyester capacitor, marked 2A473 on green body

C3 3.94 mfd, 350-volt polyester capacitor

C4 .47 mfd, 250-volt polyester capacitor

Ql МГЕ3055 NPN transistor T0220

Q2 NPN PN2222 GP transistor

II 555-dual in-line package DIP timer

Dl 1N4007 1 Kv rectifier diode

SIDAC 300-volt SIDAC switch marked K3000; see text S1DAC

Tl Switching square-wave transformer 400V TYPE1 PC

T2.3 2 25 Kv pulse transformers CD25B

SI, 2,3 3 SPST 3-amp toggle switch or equivalent

PBl 5 X 1.5 .1 grid perforated circuit board

PCTLITE Optional PCB replaces PBl PCTLITE

WR20B 36 inches #20 vinyl stranded hookup wire, black

WR20R 36 inches #20 vinyl stranded hookup wire, red

WN1 2 Small wire nuts, #71В

EN1 Enclosure 6 ‘/4 X 5 ‘A X.062 plastic, see Figure 15-4

PLATE 21/4 X 4 Vа X.062 plastic partition

TAPE 6 x 1 x.125 double-sided sticky tape

12DC/.3 12-volt DC.3-amp wall adapter 12DC/ 3

This multifunctional electrical project is very suitable for science fairs, as the device is powered by a 12 volts-direct current (VDC) battery or a tow-voltage wall adapter lranstormer (see Figure 16-1). Many interesting action and display experiments are shown in detail with safety stressed throughout, thus suitable for the younger hobbyist. Construction involves basic wiring and soldering with some basic mechanical assembly.

Most parts are readily available. Those that are special, including a printed circuit board (PCB). may be obtained through www. amazingl .com. Expect to spend $25 to $50 to complete the project as shown. Table lfr-1 outlines the parts needed for the project.

Experiments Using Your Coil

You may perform the following experiments with your coil:

• Adjustment Suspend a grounded metallic object above the device. Start at about 3 inches of separation and make adjustments, increasing the separation until the optimum spark length is obtained. (Note grounding means connection to the metal base.)

• Effect on human body Use caution as this may cause a reflex secondary reaction even though it is painless. Hold a metal object tigbtly and advance to the coil terminal. Note

the painless, tingling sensation. Fake out your pals by letting them think it is really painful. This demonstrates the “skin" or surface effect of high-frequency electricity. Caution! Make sure you are standing on a dry, nonconductive surface.

• Effect on insulators Place various objects on top of the coil and note the effects of the high – frequency electricity. Glass or other usual insulators do not stop the sparks. Experiment using objects such as lightbulbs, bottles, glass, and so on.

• Effect on partial insulators Use some wood pieces about 12 X 1 X З-inches and notice red streaks and other weird phenomena occurring from within the piece. Try other materials as well.

Ionization of gases Obtain a fluorescent lamp or plasma globe and allow it to come within several feet of the device. It will glow and produce light without a direct connection, clearly demonstrating the effects of the elec­tric and magnetic fields on the gas. Note the distance from the coil that the lamp will glow. Experiment using a neon lamp in place.

Experiments Using Your Coil

Figure 14-15 Low-voltage wiring

Obtain other lamps and note the colors, dis­tances, and other phenomena.

Indnction fields Obtain a small filament – type lamp, such as a flashlight bulb, and con­nect it between a large Viz – to 2-inch-dia meter metal or wire loop. The lamp will light due to energy coupled by induction. You will note that a current is required to light this type of lamp and is entirely different than the radia­

tion field that ionizes and causes the gas lamps to glow.

• Ion motors Create and carefully balance the rotor as shown. Use a piece of thin, spring beryllium copper. Pinprick the center with a center punch for the bearing point. The rotor will spin at high speeds if it is carefully bal­anced, demonstrating ion propulsion.

Note that your Tesla coil output is hungry for “capacitance.” It is suggested that you obtain an 8- inch toroidal terminal such as ourT08 at www. amazingl. com. You may substitute two metal bowls and attach them together to produce a spherical­shaped object. The torus, however, provides electro­static shielding of the coil, eliminating a discharge at these points.

Experiments Using Your Coil

Experiments Using Your Coil

FRONT

Cutaway view of bracket showing primary windings

– These wires are randomly positioned in mese slots. Figure 14-17 Top-plate layout showing primary coils

Tapped lead lo primary coil must be positioned close to surface of top plate as possible for avoiding arcing to secondary coil.

Tap position shown here is where the shop model is roughly tuned to arid may serve as an approximate starting point

Position and direction of tap lead will affect tuning. Experiment until you get 10-12" open air discharges.

Experiments Using Your Coil

Front view showing the control panel

Figure 14-18

Bet #

Qty.

Description

TPLATEl

і

Top plale. fabricated as shown in Figure 14-9

BPLATE1

l

Bottom plate, fabricated as shown in Figure 14-10

CBKT1

l

Capacitor bracket, fabricated as shown in Figure 14-5

SGBKT1

i

Spark gap bracket, fabricated as shown in Figure 14-6

SGFIN1

2

Heat fins, fabricated as shown in Figure 14-6

PANEL1

1

Control panel, fabricated as shown in Figure 14-8

PCBKT1

4

Primary coit brackets, fabricated as shown in Figure 14-7

LSI

1

Secondary coil form, fabricated as shown in Figure 14-4

RFC!

1

RFC choke coil form, fabricated as shown in Figure 14-5

P1L1

4

5 lh – X Ч2 – inch PVC tubing for pillar spacers, as shown in Figure 14-3

TRAN1

4

6500-volt/.02-miHiampere current limited core and coil transformer

Cl

.005 mfd.10 Kv AC special polypropylene capacitor

TUNG141

2

4* – X 1-inch pure tungsten rod, cut and faced, as shown in Figure 14-12

SI

Single pole single throw fSPST) b-amp toggle switch (see Figure 14-15)

ПИ

Panel-mount fuse holder (see Figure 14-15)

FSl

3-amp, slow-hlow, 3 ag size fuse (see Figure 14-15)

NEON

Neon indicator lamp (see Figure 14-15)

COl

3-wire #18 power cord (see Figure 14-15)

BUI

Cord clamp bushing (see Figure 14-15)

BU2

Neon lamp bushing (see Figure 14-t5)

Rl

39K, ‘A-wau resistor (see Figure 14-15)

WN1

Small wire nut (see Figure 14-15)

CAP158

15/n-inch plastic cap (see Figure 14-5)

CAP350

3 ‘/2-incb plastic cap (see Figure 14-16)

CAP

4

-’/•«-inch PVC cap used for feet (see Figure 14-13)

PLTUB1

10 to 12 inches of Vs – inch OD plastic tubing (see Figure 14-3)

TYE1

2

8-inch tie wraps (see Figure 14-11)

CLIP1

Small crocodile clip (see Figure 14-17)

WR12

15 feel

#12 AWG stranded, vinyl-covered wire

SWl

8

#6 X – Vs brass wood screws

SW2

14

#6-32 X 1 screws, Phillips

SW3

4

#6-32 X ‘A screws, Phillips

NU1

20

#6-32 hex nuts

WASH1

28

#6×1/2 flat washers; use under #6 screws and nuts

SW4

2

‘/«-20 X Ч2 – inch brass screw

Table 14-1 Tujelve-inch-spark Tesla coil parts

6KV/02A.005 M/10 Kv ITJNGt41

DB#

DB#

T08

Continued

Table 14-1

Ref. #

Qty.

Description

SW5

l

‘/«-20 x 1-inch brass screw

NU2

4

‘/4-20 brass hex nut

NU3

4

#8-32 hex nut for threads of Cl

COTUBE

7 feet

3/i6 coiled copper tubing

ROD1

4

‘/4-20 X 7 ‘/4 – inch threaded rod (see Figure 14-13)

NU4

12

‘/4-20 steel hex nut

LUG1

8

ty4-20 X #12 solder ring lug (see Figure 14-13 and 14-14)

LUG2

2

#6 solder lug for green lead of COl andTl ground (see Figure 14-14)

LUGBLOK

2

‘/4-20 block lug #YLA6 (see Figure 14-12)

LABI

General label (see Figure 14-18)

LAB2

Spark gap danger label (see Figure 14-3)

T08

8- X 2-mch spun aluminum toroidal terminal (optional)

Experiments Using Your Coil

Experiments Using Your Coil

Figure 15-1 Spark Tesla coil with timer

Тії is low-cost and interesting project generates a con­tinuous spark discharge with a variable rate of cur­rent. It operates from a 12-volt wall adapter or a battery for portable use or a science project where outlets may not be available. The device (see Figure

15- 1) has a built-in timer, allowing you to set the off and on times. This property provides excellent display for desk or bar conversation pieces where it will automatically turn on for several seconds and recycle,

surprising those in the area as the unit generates this noisy visual display.

Construction involves minimal electronic experi­ence. Expect to spend around $25 for this rewarding and interesting conversation piecc with most parts readily available. Those that are special, including a printed circuit board (PCB), may be obtained through www. amayingl. com. Table 15-1 outlines the parts needed for this project

Special Notes

The tap lead is shown being 3 feet long, enough to wrap itself around the primary coil assembly, provid­ing an additional turn. You may shorten this lead to a shorter length, bearing in mind that it will require readjustment, as it is pait of the primary coil.

If you cannot obtain open-air discharges of 10 to 12 inches, it will be necessary to experiment with the tap position along with the spark gap spacing. Open – air discharges are where the sparks emit from the output terminal into the open air. These will be longer than if they were dircct to a discharge probe. Point-to-point discharge lengths of 7 to 10 inches are possible and will he more intense but shorter than the open-air discharges.

The spark gap should be set to a maximum length where reliable operation occurs without extinguish­ing. The coil should not be operated for periods over 30 seconds due to radio frequency interface (RF1) potentials and overheating. You may have to place the system in a Faraday cage as shown on our plans as #FARAl. This will be necessary around sensitive electronic and communications equipment.

The secondary coil leads must never be allowed to route inside the coil form, as breakdown and irre­versible damage will occur (see Figure 14-3). Figure 14-4 shows a wooden block with leads secured.

Note the coil is referenced TOP and BOTTOM, where one end is slightly spaced shorter than the other. The shop unit seems to work best with the short end at the bottom. Coupling between the coils is critical and you may experiment by placing the sec­ondary coil on wooden blocks with various thick­nesses and check the results. A toroid terminal is recommended for optimum performance and you may use metal bowls.

Rpplication and Operation

Please note this Tesla coil device produces electro­magnetic radiation that can damage or interfere with certain types of equipment. Operation inside a screen room or Faraday cage may be required for FCC com­pliance.

1. Mote that only holes shown dimensioned must be precise Others may be eyeballed. 2 Corner holes are 1/4” and are located 1/2" from edges.

3. Use small pilot holes for #6 wood screws for securing the four ВКРС1 brackets.

4. Dimensioned holes are referenced from exact center

Figure 14-9 TPLATE1 fabrication

As stated previously, remove the power cord before making any of the following adjustments. The tap lead when ungrounded from the primary is a shock hazard and can produce 23 milliamperes to ground.

Optimum output requires the proper selection of the correct tap position on the primary coil. Start at the end of the outermost turn and reconnect the tap to the exposed sections, changing a quarter of a turn at a time while noting the increasing or decreasing output. You may secure it via soldering when the proper position is determined. Caution: Keep this

lead flat, as breakdown to the secondary will perma­nently damage the windings. Note the tap lead clip position and mark it when using different terminals. Note Figure 14-17 for proper routing of the tap lead, which we found tuned reasonably close with this ter­minal.

The capacitance of the output terminal will greatly affect the tuning, requiring more turns the larger the terminal size and vice versa. To operate the coil, you need to perform the following steps:

1. Place the coil on a table away from sensitive electronic equipment. Computers must be

Special Notes

FRONT

Use 3/8" to 1/2" plywood

1 Corner holes are 1/4" and mate to those on TPLATE1 in Figure 14-9.

2. Tnal-position referenced subassemblies as shown and mark hole locations for drilling 1/8" clearance holes.

Figure 14-10 Fabrication ofBFLATEl

removed from the area and disconnected from power if on the same line. Observe, read, and heed all warning labels.

Make sure the switch is “off” on the front panel before plugging the coil into a three – wire grounded outlet. Defeating the ground on the plug will result in system failure, poten­tial fire, and an extreme shock hazard.

Attach the secondary coil as shown in Figure

14- 3. Make sure that leads from the coil are as short as possible, allowing only what is neces­sary to make the connections to the bottom grounding screw and repeating for the top ter­minal. Failure to do this will result in irre­versible damage to the coil.

The spark gap can be increased just before reliable firing becomes a problem. Further spacing may produce intermittently longer discharges but may overstress the capacitor and transformer. Always set for a reliable, steady firing of continued operation. It is a good idea to space the gap at 4s of an inch when first firing up, and increase as described previously.

Figure 14-11 Isometric view of CBKTASSY capacitor bracket assembly

Assemble as shown and verify proper alignment of tungsten electrodes. Preset gap to 1/4′ and secure with lock nuts.

Special Notes

Figure 14-12 ISO view ofSGAPASSY spark gap assembly

Special Notes

Figure 14-13 Bottom plate assembly

The secondary coil should be terminated into a conductive object such as a sphere or torus A metal 13- to 16-ounce coffee can or salad bowl may also be used with reasonable results.

5. The trick now is to adjust the tap lead for the maximum spark output from the particular terminal used. Note the lead position along

with the spark output of the secondary coil: the discharge length increases or decreases as adjustments are made. Note that a variance of several inches along the primary coil winding can make a noticeable difference in output. The open-air discharges will be longer than the point-to-point ones.

Special Notes

To safety probe. Use 36" WR12

LUGS may be replaced by forming circular loops at the lead ends and securing under the screw and nuts using flat washers. If using stranded wire, always pre-tin before forming to keep intact.

Figure 14-14 Bottom plate high-voltage wiring