digital speedometer circuit schematic


Posted on Feb 4, 2014

This circuit serves to show the speed of the vehicle in kmph. An opaque disc is mounted on the spindle attached to the front wheel of the vehicle. The disc has about equidistant holes on its periphery. On one side of the disc an infrared LED is fixed and on the opposite side of the disc, in line with the IR LED, a phototransistor is mounted. IC LM


digital speedometer circuit schematic
Click here to download the full size of the above Circuit.

324 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.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Outband descrambler
Positive-peak-detector
Low-Distortion Amplifier/Compressor
Period-To-Voltage Converter
Portable Phone Preamplifier
Self-powered Fast Battery-Testers
Wide band high frequency amplifier circuit
RIAA Corrector
Dummy Transmission Circuits for Subcutaneous Transmitter
NOAA WEATHER ALERT DECODER
MULTIDIGIT DEMONSTRATION COUNTER
CF1 CF2 main circuit
Delay circuit of a multi-level output
Step-down autotransformer rotor excitation frequency starting circuit



Top