TR7 Instrument upgrade part 3
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TR7 gauges part 3

The picture below shows how the wiring progressed. I had stretched an 18 swg piece of tinned wire across the back of the unit from one gauge fixing screw to another. This was connected to the chassis and acted s a handy place to solder earth/chassis connections. (To make a piece of wire dead straight, put one end in a vice, hold the other end with pliers or a Mole wrench and pull till you feel it yield slightly. It will then be straight and reasonably stiff.)

I use a lot of spiral wrap. You can get a rather firm version from Rapid Electronics or a more pliable kind on Ebay. Spiral wrap and adhesive lined heat shrink tubing are my BFFs when it comes to wiring. (But please use a heat gun rather than a soldering iron (see Ed China) with the heat shrink. I use a B&Q paint stripper gun. It needs to be used carefully though as it pumps out a lot of heat energy. Always unplug after use to avoid accidental switch on as it could easily cause a fire. On that note, it’s excellent for encouraging a fire in our grate which does not enjoy a great draft from our chimney.)

The picture below shows a wider angle view of the back of the unit. It also shows the PCB that powers the new stepper motor fuel gauge using an Adafruit Trinket microprocessor board.

Next is the sensor for the speedometer…