Ultrasonic Range Meter

40 KHz Ultrasonic Range Meter

How to measure range using frequency? Of course, You need a device called ultrasonic range meter. In this project it uses the ultrasonic frequency of about 40 KHz. The range measurement based on the time which the ultrasonic returns from the measurement object.

In order to measure the range to an object,  ultrasonic transmitter-receiver system used.  Three digit 7-segment LED used to  display the range of measurement. The transmitter circuit of the ultrasonic generated by using two 555 timer ICs. The ultrasonic signal which was received with the reception sensor is amplified by 1000 times (60dB) of voltage with the operational amplifier with two stages.

Ultrasonic Range Meter Circuit Board

Measurement of the most short distance
When bringing the range meter close to gradually the object, display’s change stopped at about 34 cm.
The circuit this time is using 0.1µF as the capacitor of the reception signal detector for the mis-detection prevention. At less than 34-cm distance, the reception pulse is guarded with the mis-detection prevention circuit too.

To measure the short distance more, making the sending-out time of the transmission pulse short, the value of the capacitor for the mis-detection prevention must be made small. However, the energy of the ultrasonic becomes little when making the sending-out time of the transmission pulse short, and it becomes impossible to do the long-range measurement.

The most long-range measurement
The long-range measurement is difficult a little. To measure the correct distance, following condition is necessary.
- The object be perpendicular to the range meter.
- The surface of the object be flat.
- There is not object, which reflects the ultrasonic around.

Ultrasonic Range Meter Schematic

Ultrasonic Range Meter Schematic

Ultrasonic distance measurements are built using double-sided PCB and for further information visit ultrasonic range meter.

See also: 12V Switching Power Supply – Dual Power Supply Schematic