Securing the bike computer ancilliaries

The bike computer ancillary box (containing the battery, reset switch, and connections for the magnet sensor) was placed directly behind the front wheel truck. This ensured the smallest length cable possible to the bike computer.






The original road test used blue tack to hold the magnet sensor to the truck axle. The bike computer was actually supplied with cable ties to secure it to the fork of a bicycle. These cable ties are also ideal for securing the magnet sensor to the truck axle.

Invalidating my board warranty (again)

Previously I had drilled and chiselled  a recess in the board  to house the bike computer. To keep this area water tight (I didn't want the lovely Canadian ply to start separating or get swollen due to water ingress), I took the nearest paint pot to hand and painted the recess area with black paint.

Now that the bike computer was ready to be mounted onto the long board, I had to  drill another hole in the board in order to feed the bike computer cable through.



Not, a good looking result, but then again this area is covered by the bike computer. And here is the result:

Electrical repurposing of a bike computer

Regular readers of the blog will recall that I removed the back of the bike computer enclosure to reduce its thickness (I didn't want to have a chance of kicking it off). Removing the back lid  meant that the battery, the wire points connecting to the magnet sensor, and the reset switch  had to be removed. All these components required a home remote from the new slimmer bike computer. I had planned that the "home" comprising a small plastic enclosure would be positioned on the underside of the long board.

First off, I carefully soldered six wires to the existing connection points on the back of the bike computer PCB. Two wires (purple and brown) for the magnet sensor, two wires (blue and green) for the reset button, and two wires (black and red) for connecting to the battery.

Now, electrical connections on a skateboard have to be quite robust since even  riding on normal tarmac road the board is subject to a lot of vibrations. This is where UniBond 100% power glue comes in. After doing  a quick electrical test with a multimeter to confirm good solder contact for the wires and that I had not introduced any shorts, I put a big dollop of UniBond glue on the back of the PCB. I made sure that all the wires were submerged in this glue.  After 24 hours the result was a layer of resin (couple of mm thick)  on the back of the PCB securing all the wires. 

The next step was to source an enclosure for housing the battery, reset button and magnet sensor connections.This was a generic off-the-shell small plastic box available from an electronic component supplier. Once the box was delivered  I was then able to cut a piece of vero-board to fit within the box and populate it with a battery holder, reset switch and screw terminal PCB connectors.I made wire connections from the switch and battery to the terminal block connectors. I also fitted a rubber cable sleeve to the side of the box in order to reduce any strain on the bike computer cable and magnet sensor cable feeding into this box.

From the bike computer newly soldered in cable, I wired in the black and red wires for the battery, the green and blue wires for the switch. I took the existing magnet sensor cable and wired that to the brown and purple wires of the cable. 

Hey presto, I had a working bike computer. Each time I waved a magnet near the magnet sensor the LCD screen showed a "cycling" graphic.Moving the magnet close and far way in quick succession resulted in the mph reading changing!

Its time to mount all on the board!