Hi guys. I need some help - can someone design and whip up a couple of circuit schematics for me? Whilst I'm quite at home constructing them and know which end of soldering iron is which, I'm hoplessly lost when it comes to the design aspect of electronics - and my friendly neighbourhood ex-electronics engineer is too busy with work and his family at the moment to help me out. What I'm after is a low fuel warning light, and a shift light. I've googled around and found various schematics for both, so here's the info I've gathered so far: LOW FUEL: I was planning on basing the circuit on this design here: http://users.telenet.be/miata/english/misc/lowfuel.htm But I'd like to do the additional step of adding the delay to the light coming on (as per the authors suggestion) to prevent false readings due to spirited driving. I don't know how to do this - My friend intimated that it would be fairly easy, but left it at that. I'd like to be able to set the threshold at which the light turns on to a set level in the tank, but i'll need to be able to vary it in case I find that I've set it too low or too high once the car is on the road. Other information: 12V supply, Negative earth. The light will be an incandesent bulb on the dash, not an LED. The fuel gauge is discussed here in the manufacturer FAQ: http://www.etbinstruments.com/FAQ_Gauges.htm Fuel guage installation: http://www.etbinstruments.com/ETB_Gauge_Wiring_PDF/52wire3.pdf Sender ‘Full’ = 14 Ohms (It fluctuates a little, as the full movement is actually above the position of the top of the tank, so 20 Ohms from the FAQ is approx. correct) Sender ‘Empty’ = 264 Ohms Resistance across gauge = 142 Ohms SHIFT LIGHT Again, I've googled on this, and pretty much know that the heart of it will be an LM2917 Frequency to Voltage converter IC http://www.national.com/ds/LM/LM2907.pdf It shows a couple of Tach based schematics in the typical uses section of the datasheet. I need it to turn on a light for a preset number of revs. The tach pulse will be from the back of the rev counter, and that is fed from the neg. side of the coil. As with the low fuel light, I'd like to be able to set the threshold at which the light turns on. It'll come on once a set RPM is reached, but i'll need to be able to vary it in case I find that I've set it too low or too high once the car is on the road. I'm aware that I can buy shift lights, but they're all very expensive for what they do, and for the most part look a little to fast and to furious for my tastes. Other information: 12V supply, Negative earth. The light will be an incandesent bulb on the dash, not an LED. Don't know if this is useful, but the relationship between Ignition Frequency (number of pulses from the coil) & RPM is RPM = (60 * IF * 2) / C Where 60 is number of seconds in a minute IF is the ignition frequency 2 is the number of revolutions in a complete ignition cycle in a 4 stroke engine C is the number of Cylinders (6 in my case) If you can help me out, you'll have my undying gratitude and a mention in dispatches on my build blog. Maybe a pint as well. Ta GOO.