Petrol Diesel Level Sensor
The operating principle of the circuit is based on measuring the forward volt-ages of two identical diodes (check this first by measuring them). The forward voltage of a diode decreases with increasing junction temperature. lf a resistor is placed close to one of the two diodes, it will be heated slightly if it extends above the surface of the petrol. For best results,the other diode (used for reference) should be located at the same level. lf the diodes are covered by the petrol in the tank, the heating resistor will not have any effect because it will be cooled by the petrol. An opamp compares the voltage across the two diodes, with a slightly smaller current passing through the reference diode. When the petrol level drops, the output of the op amp goes high and the output transistor switches on. This causes a sense resistor to be connected in parallel with the sensor output. Several sensor circuits can be used together, each with its own switched sense resistor connected in pa...