Rangkaian Speedometer Digital
Tuesday, March 13, 2012 by skemarangkaian
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| Skema rangkaian speedometer digital |
side of the disc, in line with the IR LED, a phototransistor is mounted. IC LM324 is wired as a comparator. When a hole appears between the IR LED and phototransistor, the phototransistor conducts. Hence the voltage at collector of the phototransistor and inverting input of LM324 go ‘low’, and thus output of LM324 becomes logic ‘high’. So rotation of the speedometer cable results in a pulse (square wave) at the output of LM324. The frequency of this waveform is proportional to the speed.
For a vehicle such as LML Vespa, with a wheel circumference of 1.38 metres, and number of pulses equal to 10 per revolution, we get the relationship:
This speedometer can measure up to 99 kmph with a resolution of 1 kmph. The range can be increased up to 999 kmph by adding another stage consisting of one each of ICs 7490, 74175, 7447 and a 7-segment display.
This speedometer can measure up to 99 kmph with a resolution of 1 kmph. The range can be increased up to 999 kmph by adding another stage consisting of one each of ICs 7490, 74175, 7447 and a 7-segment display.