by walnutron » Sun May 26, 2013 5:50 pm
Hi Pebe,
Thank you for sharing your time and your talent; this is something I couldn't have done without your help or the website. I built the circuit and it works! Unfortunately I'm not getting full needle movement at the gauge, but hopefully it's just matter of tweaking. When P1 is at max. resistance, the needle shows 7/8 full and when P1 is at 0 ohm, it shows about 1/8 full. I have some numbers that might help:
*R2 is 0V to 0.76V (rather than 0V to 0.68V).
*P1 is 33.6 ohm (rather than 30 ohm).
*S to - is 0.5V to 4.3V (rather than 0V to 4.3V). You had said that zero volts would not be possible at the input to the fuel gauge from TR1. I was able to achieve as much as 4.5V, but that didn't move the needle any closer to full.
*D3 was installed and it did make the gauge needle move closer to empty (1/8 full).
Please let know if I can supply any other information that might help.
Many thanks,
Ron.