Building the front panel  PCB
2 x 1kΩ Bourns trim pots (you may re-use the ones on the speed controller PCB)
2 indicator LEDs, one red, one green
copper strip breadboard - 14 strips by 8 holes
colour-coded ribbon cable
1k5Ω resistor
2 x 3 way Molex 0.1" connector plugs
1 x 8 way Molex 0.1" connector plug
Cut the breadboard to the shape shown
Cut the six copper tracks in the middle, where the gap is shown
Solder the Molex pins on the ribbon cable and fit into the plugs. leave a reasonable length, say 10cm
Solder on the trim pots, the resistor and all the wiring, including the wiring to the rotary switch (indicated A, 1, 3 in the diagram)
Cut spacers from wood or plastic, to fit between the PCB and the front panel, deep enough to clear the trim pots. sizes are indicated by the dark patches on the diagram. Glue onto the PCB
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