Parts for DIY ultrasonic sensor, Difference im ultrasonic transducers and recivers?
rwgast_logicdesign
Posts: 1,464
Ok so while shopping for other stuff I ran across this its a 40khz ultrasonic transducer for 50 cents limit 5 I think...
http://www.goldmine-elec-products.com/prodinfo.asp?number=G19090
I have wanted to do my own sonar sensor looking around the net its not to hard and you can get better range with a DIY sensor especially at 40khz over the standar 24khz. This project is down the line but I figure I may grab these now. Here is my question.. for all you guys that know a bit about the ultrasonic stuff. All the DIY plans I see use two transducers one to send and one to recive, but there is also this labeled ultrasonic receiver
http://www.goldmine-elec-products.com/prodinfo.asp?number=G19049
These look more like the sensors on the higher end maxbotix sensors like this http://www.maxbotix.com/Ultrasonic_Sensors/High_Resolution_Sensors.htm so are these just receivers? Is this acually what is on a maxbotix module and why is there only one and not two?
http://www.goldmine-elec-products.com/prodinfo.asp?number=G19090
I have wanted to do my own sonar sensor looking around the net its not to hard and you can get better range with a DIY sensor especially at 40khz over the standar 24khz. This project is down the line but I figure I may grab these now. Here is my question.. for all you guys that know a bit about the ultrasonic stuff. All the DIY plans I see use two transducers one to send and one to recive, but there is also this labeled ultrasonic receiver
http://www.goldmine-elec-products.com/prodinfo.asp?number=G19049
These look more like the sensors on the higher end maxbotix sensors like this http://www.maxbotix.com/Ultrasonic_Sensors/High_Resolution_Sensors.htm so are these just receivers? Is this acually what is on a maxbotix module and why is there only one and not two?
Comments
From my experience, avoid like the plague when they say "Sorry, no other data or specs". You're left holding the bag with bargain parts you'll never use. Doomed to stay in your parts bin. Just barely too good to throw away.
When you get the whole sensor unit for $2, why bother? You'll never do better than that: http://www.ebay.com/itm/HC-SR04-ultrasonic-sensor-distance-measuring-module-NEW-/270961553818?pt=LH_DefaultDomain_0&hash=item3f1691319a
http://forums.parallax.com/showthread.php?135899-Four-Buck-Ultrasonic-Sensor&highlight=ultrasonic+sensor
-Phil
You can buy Piezo ultrasonic air transducers that are labeled in pairs as "receiver" and "transmitter", or you can buy single units that are labeled as "tranceivers".
Here is a typical graph of impedance and phase for a receiver/transmitter pair (Prowave 400ER180/400ET180).
The transmitter and receiver are tuned differently. At 40kHz, the transmitter impedance (solid blue line) is at its minimum, while the receiver impedance (solid red line) is at its maximum. In that way, maximum power can be driven into the transmitter, while the receiver can generate its maximum voltage. The series and parallel resonant frequencies are about 1kHz apart. This makes the transmitter and receiver curves match up for sound pressure level and sensitivity:
You can use receiver piezo as a transmitter and vice versa, but you lose the matching that comes with a pair. There are ways to "detune" the resonant frequencies by adding an inductor to the circuit around the piezo, and that can shift or to broaden the resonant frequency.
A salient difference between the pair as above, and a single "transceiver", is that the latter will be damped, a lower Q factor, so that it does not ring like a bell so long after the excitation is removed. Ringing affects the dead time necessary after transmission, before it is able to function as a receiver. A transceiver data sheet will tell you the ring time a one of its parameters, and that might be 1 or 2 milliseconds. Consider that sound travels 30+ cm in one millisecond.
agfa
Someone must be helping with the shipping costs to offset them. If we needed to return one of those sensors to China there is no way we could mail it for that price. It would cost more than $2 in shipping for sure.
Unless they have viruses and spycams built in.