Nuts and Volts - December 2015

but no green wire was available, so red and black were used instead. These leads should be about 1.5 inches long. Their other ends are left unconnected for now.

The two cables that go to the fax machine need to be soldered to the fax machine row, labeled #2 in the schematic. First, these two cables must be cut to the proper length and brought in through the two holes in the top of the case, one cable per hole. A very tight cable tie (the black object in the photo) is used to form a strain relief. This both absorbs any force on the cables and prevents them from rotating in the holes, so the internal connections are safe.

Standard telephone cable has four conductors: black and yellow at the outside two positions; and red and green at the inside two. The red and green inside conductors are designated for use as Line 1, and virtually all phones with a single line as well as virtually all fax machine connections will use them. So, the black and yellow wires (Line 2) are simply cut off; we only use the red and green ones. The two phone cables were labeled with a Sharpie pen at both ends, with “L” for Line or “P” for phone to keep them straight. That completes the wiring on the switch.

You can see the switch and the jacks are also labeled for Phone and Line. A mistake was made in connecting the jacks in the photo and it was not discovered until the final assembly, so disregard the markings on the jacks in the photo. They were correctly labeled on the outside after assembly.

Those four short wires on the C row of the switch are punched into the terminals on J1 and J2, labeled red and green. These should be the two center terminals. Instructions for this are included with these connectors. Keep in mind that this kind of insulation displacement connection relies on the wire being of a proper size. Although the instructions did not specify what this size should be, it should probably be between AWG 22 and AWG 26. That completes all the wiring (Photo 6).

Snap the case together with care so no wires are pinched. A quick label was generated with a CAD program and installed with double-stick tape. As mentioned, the jacks in the rear were marked “Line” and “Phone” with a Sharpie marker. Finally, the two cables to the fax machine were laced together with waxed dental floss for a neater appearance. The switch was installed with the double-stick foam squares that were provided, and worked perfectly when tested.

Now, faxes can be easily sent, and there is less chance of leaving the fax machine on the line when they are done. NV

■ Photo 6. Completed wiring.

QUANTITY ITEM DESCRIPTION

1 Two-port surface box Pk/5 J1, J2 RJ- 25 phone jack to fit above the surface box

1 P1, P2 Modular phone cord ( 25 foot) with modular connectors

1 S1 Miniature toggle switch, four-pole, double-throw, On-On

PARTS LIST

Motor Control Motor Control

• 15 Amps Per Channel • Dual Channel • Quadrature Encoders • DC Brushed Motors • USB / RC / Serial • 45 Amps Per Channel • Dual Channel • Quadrature Encoders • DC Brushed Motors • USB / RC / Serial