Circuit Description

Transistor Ql is connected as a free-running resonant oscillator with a frequency determined by the combi­nation resonance of capacitor C3 and the primary winding of the stepup transformer, Tl. This oscillating voltage is stepped up to several thousand in the sec­ondary winding of Tl. Capacitors C4 through C15, along with diodes Dl through D12, form a full-wave voltage multiplier where the output is multiplied by six and is converted to direct current (DC). Output is taken between C5 and С15, as shown, and may be either positive or negative depending on the direc­tion of the diodes. Different values of voltage may be obtained at various taps of the capacitors. Figure 23-2 shows the connections for the taps to ihe image lube.

The base of Ql is connected to a feedback wind­ing of Tl where the oscillator voltage is at the proper

value to sustain oscillation. Resistor R2 biases the base into conduction for the initial activation. Resis­tor Rl limits the base current, wheras capacitor C2 speeds up the deactivation of Ql by supplying a neg­ative bias and capacitor Cl bypasses any high-fre – quency energy. The input power is supplied through switch SI via a “snap-in” battery clip.

Circuit Rssembly

To put the circuitry together, follow these steps:

1. Lay out and identify all the parts and pieces, checking them with the parts list. Note that some parts may sometimes vary in value. This is acceptable as all components are 10 to 20 percent iolcrant unless oiherwise noted. A length of bus wire is used lor long circuit runs.

2. Create the PB l perforated circuit board as shown in Figure 23-3. Enlarge the holes as follows:

Thirteen Vitrinch holes for the junctions of the diodes and the capacitors in the multiplier

Note that Ql may require a heatslnK II battery voltage exceeds В volts.

Vc COMMON

Circuit Description

Circuit Description

Figure 23-2 Power supply schematic

Circuit Description

Figure 23-3 Assembly board

Seven ‘/«-inch holes for mounting the switch (SI) and the external connection leads

The switch is shown attached to the assembly board but may be remotely located using interconnecting leads.

3. Assemble the board as shown in Figure 23-3. Start to insert components into the board holes as shown. Note to start and proceed from right to left, attempting to obtain the lay­out as shown.

Certain leads of the actual components will be used for connecting points and circuit runs. Do not cut or trim at this time. It is best to temporarily fold the leads over to secure the individual parts from falling out of the board holes for now

Note that the solder joints in the multiplier sec­tion, consisting of C4 through C15 and D1 through D12, should be globular shaped and smooth to pre­vent high-voltage leakage and corona. The solder globe size is that of a BB. Run your fingers over the joints and verify the absence of sharp points and pro­trusions.

Also note thatTl is laying on its side and uses short pieces of bus wire soldered to its pins as exten – r ч sions for connections to the circuit board.

W

Circuit Board Testing

To test the circuit board, follow these steps:

1. Separate high-voltage output leads approxi­mately 1 inch from one another.

2. Connect 9 volts to the input and note a cur­rent draw of approximately 150 to 200 mil – liamperes when SI is pressed.

3. Decrease the separation of the high-voltage leads until a thin, bluish discharge occurs, usu­ally between Чг to 3A of an inch. Note the cur­rent input increasing. The increased value depends on the length of the spark, corona, and so on, but should not exceed 300 mil-

1 і amperes.

4. Check the collector tab of Ql and add a small heatsink if too hot to touch. A heatsink tab is shown in Figure 22-4 (Chapter 22).

For those with a scope, it may be interesting to note the wave shape at the collector tab, as shown in Figure 23-2. Note this is without any sparking occurring.

Note the takeoff point for the focus lead. This point is approximately at ‘k the output voltage. The unit may be powered up to 12 volts-direct current

Circuit Description

Figure 23-4 X-ray view showing innards

(VDC) but will positively require a heatsink on the tabofQl.

This unit is capable of producing 10 to 20 Kv from a small, standard Ч-volt battery. It is built on a printed circuit hoard (PCB) or a small piece of perforated cir­cuit board and can easily be housed or enclosed, as the application requires. Applications include power­ing image converter uibes for night vision devices, ignition circuits for flame-throwing or – producing units, capacitor charging for energy storage, shocking clectric fences, insect eradication, Kirlian photogra­phy, ion propulsion electric field generators, ozone producing, and more.

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