Nearmiss-o-meter Build Guide, Part 2

Build Guide, Part 2

This part of the build guide uses the switch PCB design available here on GitHub. As with the main board, it is possible to replicate the circuit design using a pegboard.

The Switch PCB

Clean Up the PCB

When the boards are manufactured, they often have small 'nibs' left on the edges (circled red). Carefully break these off with a small pair of pliers and use a file to remove the remnants. If you're using the 3D printed switch case, make sure all edges are cleaned up.

Click on the picture for an enlarged view.

Molex Connectors and Ribbon Cable

Solder Molex Connectors to Ribbon Cable 

If you've soldering the cable directly to the main board PCB, you can skip this step.

The Molex connectors are designed to be crimped, but the crimping tools are absurdly expensive, so a small dab of solder and manual crimping will have to suffice.

I've temporarily mounted the four individual connectors onto a spare PCB header which helps solder the ribbon cable a little more accurately. Make sure the 'barbs' (arrowed) are all facing up.

The red marking on the ribbon cable I've used denotes the switch wire. The opposite side ins the ground and the centre two are for the LEDs

UPDATE: Thanks to Paul for this crimping tool recommendation - much, much easier (and more secure) than soldering all for less than a tenth of the price (£23) of the official Molex ones.

Molex Plug

Insert Connectors into Molex Plug

Once soldered, crimp the connectors over the cable insulation and then push into the Molex plug casing, ensuring the barbs locate in the square holes (arrowed).

Switch on PCB

Solder the Momentary Switch to PCB

Straighten the switch legs and splay them out slightly. This will allow the switch body to sit directly onto the PCB.

Solder the legs from the back, ensuring the switch doesn't 'pop-up', then cut off any excess.

LEDs on PCB

Solder the LEDs to PCB

Mount the LEDs tight to the PCB. Note the positive tails (arrowed, slightly longer) and both to the inside.

Solder from the back and then cut off the tails.

Ribbon Cable, Switch End

Cut the Ribbon Cable

Cut the ribbon cable to the required length (this will depend where you mount the switch relative to the nearmiss-o-meter on the bike - I've cut to approximately 280mm long).

Leave the switch wire (red stripe on my build) about 10mm longer than the other three.

Solder the Ribbon Cable to Switch PCB

Tin the ends of the wires an push through the PCB from the top. Double check the routing from plug to PCB is as per the photograph, solder from the back and snip off any excess.

That's it!

Next up, the Arduino code and case fitting.