 Ultrasonic sensor
This time, I used open air type sensor (T40-16 and R40-16) made by Nippon Ceramic company. First, I used a drop-proof type sensor (MA40E7S and MA40E7R) made by Murata company. The specification is the same approximately. However, it wasn't possible to have done the detection of the needed distance. Therefore, I changed in T40-16 and R40-16. As for the drop-proof type, the outside is enclosed by the mold. Therefore, the efficiency of being ultrasonic seems not to be good.
 MA40E7S,R made by Murata,.co
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| The brief specification of the ultrasonic sensor is shown below. |
| Item | Spec |
Resonant
frequency
(KHz) | 40 |
Sound pressure
level (dB) | 106 < |
| Sensitivity (dB) | -74 < |
Size
(mm) | Diameter | 18.0 |
| Height | 12.0 |
Terminal
interval | 10.0 |
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As for the detail specification, refer to "Piezoelectric Ceramics Sensors("PIEZOTITE")".
Adjustment of the receiving sensitivity
At the receiving circuit this time, a receiving signal is amplified 1000 times. It is 100 times at the 1st stage and 10 times at the 2nd stage of IC4.
When using the sensor which is made by above-mentioned Murata or when developing a detection distance, to raise receiving sensitivity brings a good result. If doing the 2nd stage by 50 times, it becomes 5000 times of amplification at the total. But, there is possibility to oscillate when raising too much. Be careful.
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