petrol diesel level sensor

Download Petrol Diesel Level Sensor

Post on 20-Apr-2015




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Petrol/Diesel Level SensorPaul de Ruijter (The Netherlands)This sensor is particularly suitable for use in small spaces, such as the petrol tank of a motorbike. It has the advantage of not having any moving parts, unlike a conventional sensor with a float and float arm that make it difficult to fit in a tank. The sensor circuit is made from standard, inexpensive components and can be put together for little money.SENSOR +6VR1 100k R2 120k

IC1 = LM358LEVELR5 R6 100k R7 120k 8 R10 R

0V C1 100n R3 100R 3 2 1 R4 22k





5 6




R9 22k

BC847D1 D2

R8 100R

BC847D3 D4


The operating principle is based on measuring the forward voltages of t wo identical diodes (check this first by measuring them). The sense resistor connected in parallel with the tom so that splashing petrol does not cool forward voltage of a diode decreases with output, and the resulting output signal can be the heater resistor, since this would result in false readings. increasing junction temperature. If a resistor used to drive a meter or the like. is placed close to one of the two diodes, it will Using this approach, the author built a petrol The circuit should be powered from a regube heated slightly if it extends above the sur- tank sensor strip tank consisting of five PCBs, lated supply voltage of 5 to 6 V to prevent the face of the petrol. For best results, the other each fitted with two sensor circuits. With this heating resistors from becoming too hot. Personal Download for Gunawardena, Kapila | copyright Elektor diode (used for reference) should be located sensor strip installed at an angle in the tank, a After testing everything to be sure that it at the same level. If the diodes are covered resolution of approximately 1.5 litre per sen- works properly, its a good idea to coat the by the petrol in the tank, the heating resis- sor is possible. Many tanks have an electrical circuit board with epoxy glue to provide bettor will not have any effect because it will be fitting near the bottom for connection to a ter protection against the petrol. cooled by the petrol. An opamp compares the lamp on the instrument panel that indicates Tip: you can use the well-known LM3914 to voltage across the two diodes, with a slightly the reserve level. The sensor strip can be used build a LED display with ten LEDs, which can serve as a level indicator. Several examples of smaller current passing through the reference in its place. diode. When the petrol level drops, the outsuitable circuits can be found in back issues put of the opamp goes high and the output You will have to experiment a bit with the val- of Elektor. transistor switches on. This causes a sense ues of the sense resistors, but do not use valresistor to be connected in parallel with the ues lower than around 100 . It is also impor- Note: this sensor circuit is not suitable for use sensor output. Several sensor circuits can be tant to fit the diodes and heater resistor in a in conductive liquids. (100335-I) used together, each with its own switched little tube with a small opening at the bot-

2x 1N4148

2x 1N4148

100335 - 11


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