179: Tuesday 22nd February 2011

Yesterday I fitted the instruments to the car and went for a test drive. The gauge was way too sensitive and was going all the way round to 8 (800A). I set the car to economy as I knew that it would top out at 500A. I wound the adjustment back on the display circuit and with some trials I got the display to go up to 5 and stop when pulling away in economy mode. Then I put it in sport mode and this also stopped at 5. Clearly this was no good. I wound it out again until I was reading 8, then I realised that the adjustment was just to set how much of the display is used. What I needed was a pre-scalar. I drove it like this today and I estimate I need to trim the signal down by a factor of between 3 and 4. I went to my local electronics store today and bought a multi-turn potentiometer so I can set up a potential divider on the input to the display. Using a multi-turn potentiometer means that by adjusting with a screwdriver, I can get a really fine adjustment. I shall build this onto the display circuit on Friday when I have more time in the daylight. Hopefully then this will work how I expected. I must confess that getting these gauges to work is a bit of a fine art. I shall get there soon be sure. I am looking forward to making some videos soon to show you all the different parts of this project. It is hard to show with just pictures and text.

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