The two USB cable assemblies will be cut to length then modified to remove the shielding (a braided wire covering with a bare drain wire) and the white and green data wires. Since the extractor only uses USB power and doesn't process data, we will only need the red and black wires.
The next step is a bit tricky, but if you take it slowly and carefully, you'll find that this technique is an excellent way to remove the thick outer insulator of a multiconductor cable without damaging the internal conductors.
- Cut the two USB cables to the indicated lengths. We won't need the male conductors for the extractor, but you may want to keep them in your parts bin for a future project.
- To remove the outer black vinyl sleeve, bend the cable back sharply within 1/4 inch of the panel mount connector.
- Holding the cable and connector in one hand, slowly and lightly draw the blade of a sharp hobby knife back and forth across the vinyl sleeve until you feel it contact the first layer of the cable, the braided shield -- then stop cutting. You should see the braid peeking through the slot you just made.
- Work your way around the entire circumference of the cable, bending the cable as needed to cut through the vinyl sleeve to expose the braided shield.
- To remove the vinyl sleeve, lay the cable flat on a tabletop. Draw the knife blade along the length of the vinyl sleeve in a straight line, splitting the sleeve but not cutting deep enough to score the braid. Start at the point where the braid was exposed and scribe the sleeve to the cut end.
- You should be able to grasp the scribed sleeve with your fingers and pull it away from the cable. The sleeve should easily give way along the scribed cut line.
- Remove the braided shield by pushing it towards the panel connector. The braid should bunch up as shown.
- Use sharp wire cutters or scissors to cut the small braid wires close to the panel connector.
- Once all the small wires are cut, slide the braid off the cut end of the USB cable.
- Untwist the bare shield drain wire and the secondary shield foil. Use the wire cutters to cut them close to the panel connector.
- Cut the white and green data wires as shown. To keep the ends of the data wires from touching any other wire or remnants of the shield, cut the white wire 1/8 inch from where the shield was removed. The green wire should be cut 1/8 inch longer than that so that its end won't touch the end of the white wire.
- Repeat the process for the other USB cable.
You now have two USB panel connectors with just the red and black power wires that will be connected to the PowerBoost board later.
Cut the remaining component wires as follows. Save the wire cuttings to re-use for the power switch and for the N-Channel MOSFET.
- Cut the black wire to 3 inches in length; save the remnant for the N-Channel MOSFET
- Cut the red wire to 5-1/4 inches
PIR (Motion) Sensor cable:
- Cut the yellow wire to 4-1/4 inches; save the remnant for the On/Off Switch
- Cut the black wire to 4 inches; save the remnant for the On/Off Switch
- Cut the red wire to 4 inches
- Cut the yellow and black wires (remnants from the sensor) to 4 inches
- Cut the black wire (remnant from the fan) to 4-1/2 inches
This is the wiring diagram for the extractor. We'll solder wires to the N-Channel MOSFET's pins and the power switch before connecting all the component wiring to the PowerBoost 500C board.
For this step you'll need the fan, the N-Channel MOSFET, the three-wire connector for the PIR (motion) sensor, the 4-1/2 inch black wire, and three short lengths of heat shrink tubing. When this step is completed, it will look like the photo on the right.
- Prepare the MOSFET's pins by bending them as shown with a pair of needle nose pliers.
- Slip a heat shrink sleeve over the sensor connector's yellow wire and slide it out of the way.
- Bend the tinned end of the yellow wire into a U-shape.
- Interlock the wire with the MOSFET gate pin (G), then solder the two together.
- Repeat the soldering process for the black fan wire that connects to the MOSFET drain pin (D) and for the 4-1/2 black wire that connects to the MOSFET source pin (S).
- Cover the connections with the heat shrink tubing. Shrink the tubing with the shank of the soldering iron tip.
- Bend a tinned end of the 4-inch black wire and the 4-inch yellow wire into a U-shape.
- Slip the black wire into the hole of the center terminal of the On/Off Switch. The yellow wire attaches to one of the remaining two terminals.
- Solder these two connections.
Solder the component wires to the PowerBoost 500C board as shown in the wiring diagram.
Everything should be connected now, except the battery. Double-check the wire connections per the wiring diagram. If it all checks out, you're now ready to move on to the testing phase where we'll plug in the battery and watch as the fan spins and lights glow.