177: Monday 14th February 2011

I mounted the sensor on the negative connection using some plastic tubing to make it the right size to fit snug. In the photo below you can see the blue sensor with the sensing wires coming off the side.
Next was the instrument cluster. I connected this up on the bench and it took 21 photos to get these 2 shots showing the numbers lit up. This is indicating 800A current draw (or it should be when it is on the car).
This is a closer shot. I was seeing loads of glare on the other shots, so I just deleted them. I fitted it all back up in the car and hey presto....... it didn't work! I had my foot on the brake and I eased the power in. I could see the current on my controller programmer tester display, but no change on the gauge. I disconnected the sensor and all 9 LEDs lit up. This was to be expected, so at least I could see the display circuit was working. I tried winding the adjustment screw to both extremes and still there was no display with the sensor connected. I checked the voltages at the connector and there was a problem. The supply was good for 5v at 5.03v, but the reference should be 2.5v and that was 5v and so was the signal sensed. I boxed it up again in the car , but I routed the wires so that I only needed to remove the panel by my feet to get to the circuit and all the connections. Tomorrow I shall investigate what is going on with the sensor side. The only other thing I could think of was that the wire insulation and the plastic pipe were blocking the magnetic fields? I shall get the right voltages first then I might change the mount to 22mm copper pipe and put it in the power circuit to get better sensing.

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