138: Friday 30th April 2010

I got home from work and stripped the instrument cluster from the Probatron. I had 10 x 5mm blue LEDs and was planning to mount them behind the mask for the rev counter to show the instantaneous Amps (x100). I had been to the electronics store on my way home and asked what they had for 3mm red, yellow and green LEDs, but someone had been in and bought just about all of their stock. So with the task of lighting up the ammeter in hand, I drilled the holes in the plastic behind the mask in line with the numbers on the dial. I put a 5mm blue LED in my prototype board to light it and held the dial over it. I found that didn't shine through as bright, so I went back to the electronics store to get ultra bright LEDs. They didn't have any ultra bright 5mm blue LEDs, so I came away with 3mm ultra bright LEDs in the following colours; 1 x red, 2 x orange, 2 x yellow and 5 x green, making 10 in total, all for the fuel gauge conversion. In the photo below you can see the holes drilled in the plastic behind the fuel gauge mask. I had drawn the blue line where the stripe was and by the application of trigonometry I worked out how far apart they needed to be around the circumference and using my vernier calipers I put scratch marks where I needed to drill.
I then set about mounting the LEDs in the holes. I tested each one before fitting it to be sure. In the first hole went the red LED, then the first orange, but the next hole was by thinner plastic, so when I put the super glue on, it kept falling over. I went to get my pliers so I put a sticky foam pad on the legs of the other LEDs to hold this one, I got the LED legs in my pliers and went to put it in then dropped it on the floor. After 20 minutes on my hands and knees sifting through swarf an dust and scraps of wire and metal etc. I abandoned my search and decided to proceed with 9 LEDs. I put the 2 yellow LEDs in with great care. When it came to the 5 green LEDs I thought I would test them all first, wise move! I found one was blue and one did not work at all. So I decided to mount the blue one next followed by 3 greens. In the photo below, you can see all the LEDs mounted and 2 spare holes that I will come back to another day. I was happyish to settle for 8 LEDs for now. It was better then having a project box hanging out of my air vent. So now I can't tell when it is fully charged properly, but I am more interested in when it is getting low than when it is full right up. My super glue was past its sell by date, so it took a while to set. It would have been a lot easier with fresh super glue. In case of global understanding, super glue is cyanoacrylate glue. I know there are several names for this, but in the UK it is best known as super glue.

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