Step 3Adding the resistors.

There are four resistors to install and to keep things simple they are all the same value - 1000 ohms. 

They are not polarity sensitive, so can be inserted any way round. Perfectionists might like to make the colour bands all read in the same direction.

The group of three resistors in parallel are for the MOSFET control, while the one that sits at the bottom of the PCB on its own is to limit current through the power indicator LED to a few mA.

The colour code on each resistor reads as follows. Brown (1), Black (0), Red (2), Gold (5%). The resistor value is worked out as 1, 0 and a multiplier of 2 which means two more zeros. Therefore it is 1000 ohms. The gold band indicates that the measured value has a tolerance of plus or minus 5%.

Step 4Adding the decoupling capacitors.

The decoupling capacitors are 100nF ceramic capacitors. Their function is to help suppress any spikes or transients that might find their way onto the power supply. There is one on either side of the voltage regulator.

These capacitors are not polarity sensitive, so they can be put in any way round.