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illman found considerable stray current in his metal cabinet but solved the problem by insulating the metal capacitors

In document Build your own Doug coil machine (Page 70-84)

This is the 30 ȝf capacitor. The dark strip of wood on the left edge of the panel is a cap of cherry that hides the edge of the plywood when this plywood was used as a shelf long ago.

These are two of the cable tie mounting bases. They have slots for the cable ties to pass through and up around the capacitors. The ties are 7 inch ties and are just long enough for all the capacitors used in a CM.

The mount bases have an adhesive backing but when mounting the larger capacitors there is some prying action when you tighten the cable tie and the adhesive releases. This prying occurs because two bases are used for the large capacitors so they can cradle in the gap between the two mounts.

This 30 ȝf (-; !!9) capacitor is the only one on switch B. I label all capacitors to avoid mistakes in wiring to the switches. Avoid pulling too tightly on the cable ties. The capacitors shouldn¶t move around but make the tie just snug enough.

These capacitors for switch C, each 8 ȝf (-; 0942) will be connected together in a parallel circuit so they should be mounted near each other.

On the next page these capacitors will be connected in a parallel circuit

The 4 ȝf (-; 094!) capacitor for switch E has

been mounted to the panel and above the 8 ȝf (-; 0942) for switch  will follow.

The short pieces of 12 gauge wire have their ends stripped of insulation and the spade connectors will be crimped on. These wires are used to connect the two capacitors in cap array C together in a parallel circuit.

Use this section of the crimping tool to secure the connector to the wire ± be sure there is no wire insulation in the

aluminum collar that will be crimped. Also be sure that the wire does not turn independently of the connector ±if it does crimp It some more. Notice how flattened the yellow insulation is where the crimping pliers were used

The capacitors used in a CM do not have plus and minus terminals. By connecting the top terminals together and the bottom terminals together you get a parallel

circuit (even if you turned one of the capacitors 180 degrees and rewired it. Here the panel is lying flat and in the picture to the right it is upright on its edge ± the way it will be mounted in the cart.

Here is the entire side of the first panel. There is no capacitor for switch A. Switch A is used for frequencies that require capacitances larger than 62ȝf which is the sum of all capacitors in a CM.

These 4 ȝf (-; 092!) capacitors for switch F will be in a series circuit. It doesn¶t matter which ends you twist together. Hold them as shown. Leave about ¾´ of wire Is between the capacitor and where they cross.

They will be twisted together with fingers so once you start the twist be sure to pinch the spot where the wires cross so the twisting doesn¶t migrate down toward the capacitors.

They don¶t all work out to be this neat but this one makes a good picture.

Trim the ends but not so much that the twist is loose.

All of the twist connections like this must be soldered

ecide where you want to place them then attach mounting bases and cable ties or drill holes and use cable ties.

This series connection of 2 - 4ȝf (-; 092!) capacitor

will be connected to switch F For switch G three 3 ȝf (-; 092!) capacitors will be connected in a series circuit

Twist the wires together as before - place the array to determine the location of mounting bases.

Using a marker to label helps when wiring the capacitors together.

Its just another way to keep yourself organized

Capacitor array H two 1 ȝf (-; 095) to be connected in series to switch H is shown mounted on the panel. Notice that the wire twists that will be soldered are all out where a soldering iron can be used very easily.

The capacitors for switch I involve a parallel and a series circuit. First connect two .47 ȝf (-; 0954) capacitors end to end. Use needle nose pliers to make a bend In each of the free wires so they are perpendicular to the two joined capacitors. Connect a .015 ȝf

(-; 095) to these free wires which results in a parallel connection I used pliers to twist these connections since the available wire for the parallel connection is limited in length.

parallel

series

Just a few more arrays on this panel will be enough.

Switch J is connected to capacitors in a parallel circuit.

Connect a .1 ȝf capacitor (-; 0954) front to front and back to back to a .022 ȝf capacitor (-; 095).

They are shown here mounted to the panel.

Switch K is connected to two capacitors connected in a parallel circuit. Connect a .047 ȝf (-; 0955) capacitor front to front and back to back with a .015 ȝf (-; 095) capacitor. on¶t twist the wire so much that the capacitors get close together.

The second panel is finished. All the wires on the left of each array will be connected to their respective toggle switches. The wires on the right of each array and all other capacitor arrays will be joined together and go to one of the terminals on the binding post. The binding post is where the coil plugs into the system with banana plugs.

F

G

H I

J K

We are now working on the second panel (the third side for capacitors). This side will contain the remaining capacitors and the other side of the panel will contain the resistors.

Shown is the capacitor for switch L. It is a single .033 ȝf (-; 0955) capacitor.

This is another single capacitor for switch M. It is a .015 ȝf (-; 095) capacitor.

Switch N connects to this Single .01 ȝf

(PART (0952) capacitor.

Switch O connects to this series circuit consisting of two .015 ȝf (095) capacitors. The switches are located to the right. Both panels will be mounted in a perpendicular direction to the back of the switch panel Switch P connects to this series of two

.01 ȝf (-; 0952) capacitors.

In document Build your own Doug coil machine (Page 70-84)