How to build a versatile LED Light Base with an USB Smartphone Charger as power supply.

After I had finished my recent Instructable (Back-to-the-Future-Plutonium-Fuel-Cell), I needed an adequate lighting. As the Fuel Cell has a diameter of 80mm, the Light Base can also be used for other objects :-)

Let's take a look at the stuff we'll need.

1. Tools and Materials

1.1 Tools

Drilling Machine

Cone drill (0-20mm at least)

Metal Drill (4mm; 5,5mm; 8mm)

Counterbore

Set of Key files

Cutter

Ruler, Caliper gauge, Marker

Wrench, Size 7 (for M4 nuts)

Screwdrivers

Wire cutter

Wire stripper

Pliers or Bending tool (e.g. Conrad.de 425869)

Soldering iron and solder (diam 0,8mm)

1.2 Materials (for about 40€)

Housing 115x90x55mm (e.g. Reichelt.de: 1550WC)

4 Bolts M4x50mm

4 Washer M4

12 Nuts M4

Spray Paint

Stripboard 100x100mm (Grid: 2,54x2,54mm) (e.g. Reichelt.de: H25SR100)

9 LED 5mm white 18000 mcd (e.g. Reichelt.de: LED-5-18000-WS/3)

9 Spacers of 9mm for LED (e.g. Reichelt.de: MEN 2819.5090)

9 Resistor 68 Ohm 0,25W (e.g. Reichelt.de: METALL 68.0)

Stranded Wire red 1x0,14mm (e.g. Reichelt.de: LITZE RT)

Stranded Wire black 1x 0,14mm (e.g. Reichelt.de:LITZE SW)

Circuit breaker (e.g. Reichelt.de: WS R13-244 A)

USB-A connector (e.g. Reichelt.de: USB AW)
USB-A cable (L=1,8m) (e.g. Reichelt.de: AK 670/2-2.0)
USB Charger (5,3V; 200mA at least)

Step 1: Step 1: Building the Circuit

The circuit consists of 9 bright white LEDs with adequate dropping resistors and a USB-A connector for power supply. The circuit breaker is attached to the housing and connected to the circuit.

Because of the shape of the housing, the Stripboard is screwed on the cover with M4x50 bolts (see step 2).

1. Prepare the Stripboard by cutting it to 25x26 holes and drill the 4 holes (diam. 4mm) for fastening.

2. If necessary, clean the copper stripes with degreaser. Place the components on the board like shown on the picture. Mind the polarity of the LEDs and the +5,3V pin of the USB connector. Place also the 4 bridges (2x red and 2x black wires) on the board. Start soldering, then cut the legs of the components.

To keep an equal distance between LEDs and Stripboard I used 9mm spacers for the LEDs.

3. To connect the circuit breaker, cut 4 pieces of wire (2x red and 2x black) and strip them at the end. Solder one end of the black wires to the negative side of the USB connector and the negative stripes of the circuit. Do the same with the two red wires by soldering them to the positive side of the USB connector and the positive stripes of the circuit.

Step 2: Step 2: Preparing the Housing

The housing is made of pressure die cast aluminium and thus it is easy to machine.

1. To prepare the cover, we have to drill 4 holes for the M4x50mm countersunk bolts to support the stripboard. Before, take the stripboard as stencil to mark the exact position of the bores.

2. To prepare the housing, we have to fasten the bolts and place the stripboad at 30mm over the cover. To avoid short-circuits via the bolts, I protected the copper stripes with electrical tape.

3. Now transfer the position of the 9 LEDs on the outside of the housing (diam. 5,5mm). To make fit the LEDs in the holes countersink the 9 bores. As the space is very limited, I took a 9mm metal drill instead of a counterbore.

4. Do the same for the USB connector. Drill 2 holes of diam. 8mm and complete the vent with a key file.

5. Mark also the hole for the circuit breaker in the middle of the side-panel of the housing at 16mm from the cover (diam. 20mm).

6. To finish the housing, I used black spray paint. The seal is thus virtually invisible.