Improved Low Fuel Indicator

052 IMPROVED LOW FUEL INDICATOR The indicator described here obviates the flickering of the "low fuel" warning light on the dashboard caused by vehicle move- ment. The indicator ensures that the light remains extinguished until the duty factor of the signal supplied by the fuel sensor is smaller than 0.5. When that happens, the light comes on and remains on until the fuel tank has been filled to a sufficient level. The present circuit tests the light by causing it to flash for about 5 ELEKTOR ELECTRONICS JULY 1989 SUPPLEMENT seconds everyt time the ignition key is turned to start the engine. The signal processor is switched on together with the ignition. Initially, C1 is discharged, enabling oscillator N2 via inverter Nl. One input of N3, pin 12, is connected to R3-C3, the time constant of which is equal to that of R1-C1. If the output of the fuel sensor is high, pin 12 of N3 is held high via R2-C3. The 1.5 Hz signal from oscillator N2 is inverted by N3 and passed to darlington CA...