34

Your linked description shows that the tweeter is intended to be used with a woofer for music reproduction. The description doesn't cover use of the tweeter as a specialist ultrasonic transducer on its own. The power rating indicates that the tweeter is intended to be used with a 350 W average/700 W peak audio amplifier driving both tweeter and woofer. For ...


30

Basically, sound is slow. Using sound you can easily time how long a wave takes to travel to your object and reflect off it, thus giving you a fairly accurate distance. Light goes too fast for that, unless you are looking to measure the distance of the moon, say. And why ultrasonic? So you can't year it. Imagine how annoying it would be if you were forced ...


26

The best idea is to ignore what everyone says, and test it yourself. Install an app like "SpectralPro Analyzer", and either generate some high frequency sounds using PC programming (easy) or download some high-frequency MP3's from web sites. I've done all of the above on many different phones - I find that I get excellent results for a very long way off ...


21

It appears that the problem lies with the power ratings of loudspeaker components being the power rating of the system and not that of the individual component. For example, in the 1970s, Philips were specifying the ratings of individual speaker components. In later years, it may have been felt that specifying the system power would make it easy to select ...


19

There is some analysis at https://electronics.stackexchange.com/a/130095/9006 in answer to a question about finding the position of an object. Light, radio and heat radiation are all electromagnetic radiation, and travel very, very quickly. It is not automatically true that they provide a better result just because they are faster. Electromagnetic ...


15

Generally, yes (confirmed by both theory and experiment) though probably not as effectively as they can lower frequencies. There are three primary factors: 1) The maximum frequency which can be produced by your source's DAC and associated anti-aliasing filters. This is usually a bit below the Nyquist frequency for your effective sample rate, how far will ...


12

3 come to mind. An IR encoder as RoyC mentioned. Paint the back or sides of the weights alternating white and black. A camera as you already mentioned. OpenCV would make quick work of this. And You can do it at a distance without touching anything on the machine. And the last option is an actual weight sensor. A load cell placed under the weights. When ...


11

Coincidentally, I happen to be playing with almost precisely what the question refers to, since yesterday. My distance sensor unit boasts a 25 degree angle, but I faced the same problems with my bucket of water. My solution may not be an engineering marvel, and there will likely be some reaction from purists, but here is what works: The sensor unit is set ...


11

I'm afraid that you are another Amazon victim. I note that you have linked to an Amazon ad rather than a manufacturer's datasheet which would explain how the device is rated and expected operating conditions. Our motto here is, "No datasheet? No sale!". I expect that a similar device from a reputable manufacturer might give the amplifier rating at ...


10

But the receiver and the transmitter are placed side by side. Won't the receiver immediately pick up the signal as it is sent? How does ignore the signal as it is sent, and record it only as it returns after being reflected by the target? In a pulsed system (the most common type), the receiver is blanked during the period of the transmit pulse so it does ...


10

Most common audio equipment is set to match human hearing, 20Hz to 20kHz is their operating range. So you want to measure ultrasound, If you want only to measure high frequencies, you can use a bat detector or something to go a bit above 20kHz, it wont be able to detect "normal" sound though.If you want everything from 20Hz to 100kHz or something like that ...


10

The power ratings for audio equipment are often completely bogus. Check out the amount of copper in a 350W motor (and note that a speaker is also essentially a motor, only the motion is linear instead of rotational): There's nothing in the photo for size comparison, so I'll just note the diameter is about 5" (13 cm). Guessing a power rating from a ...


8

Is it possible that you scraped off part of the part number printing and that the part is actually like: ...implying a part number CD4060B ?


8

I would strongly recommend against attempting any sort of audio output transformer to boost the output of the op amp like is being suggested in the comments. Don't get me wrong, it is a perfectly valid and frequently used technique. In reality, it's just a kind of impedance matching, and impedance matching transformers work great for this, and let low ...


8

By definition of the audio range for humans, beyond 20kHz is beyond audio. There are audio equipment designers such as Rupert Neve who believe the range could be wider, but this is not necessarily based on strong evidence. The vast majority of audio equipment therefore is limited to this maximum frequency, and you will never be able to do it. Some ...


7

A laser-based "virtual cane" for the blind is a very sensitive option for travel assistance to the visually impaired. It is far more precise than an ultrasonic sensor, and also much smaller and less power-hungry. The concept dates back to the 1950s (not using lasers, just incandescent narrow-beam lights), and practical laser cane implementations are known ...


7

I assume the pipe is only to protect the sensor from environment noise. If the pipe is not filled with anything, then just line the inside of the pipe with sheets of sponge or foam to eliminate or reduce internal reflections. Searching the net yields results for sound proofing foam sheet Images from amazon.com and efoam.co.uk (no affiliation, just top ...


7

Ultrasound Sensors measure the distance by sending an ultrasound signal and measuring the time it takes to be reflected from the object and come back. The biggest problem are reflections inside the pipe, which can be solved using sound absorbing material inside the pipe. Another problem is, that the speed of sound is dependent on air pressure. Even small ...


6

If we look at the source code for pulseIn we can see it doesn't use any of the timers. The pulseIn function loops until the pulse finishes and then converts clock cycles to microseconds. The cause of your problem might be interrupts when the servos are active. Somewhere in the middle of your measurement, in the pulseIn function, an interrupt occurs which ...


6

See Kerry Wong's article You'll need to create something like the following circuits Personally I'd buy one of the pre-built modules that are much easier to use As others have noted, using separate Arduinos for transmit and receive will make the project much more complex and less accurate. I haven't tried any of the above and can't vouch for it. ...


6

No. "Active" speakers with their own power supply and amplifier will usually have filters in them that roll off above 22kHz. They're not designed to be capable of emitting ultrasound, and the filtering is there to eliminate induced noise from other sources. You might be able to get very weak ultrasound out of a small passive speaker, but again it's not ...


6

Here is what appears to be a very informative document entitled "Underwater Radio Communication" by Lloyd Butler VK5BR. Here are some interesting extracts. Attenuation (α) in dB/metre = 0. 0173 √(fσ) where f = frequency in hertz and σ = conductivity in mhos/metre (siemens per metre) Here's a useful graph linked with the above formula. It basically plots ...


6

820kHz and 2.5MHz (=3*820kHz) are eigenfrequencies of the mechanical system. You will be able to drive the transducer at any other frequency, but the damping will be greater by orders of magnitude, so it won't be usable. Some ultrasound transducers can oscillate at both longitudinal and transverse mode. It is possible that that 820kHz and 2.5MHz are the ...


6

An idea once I had, but never tried, is to treat an ultrasonic transducer like a high-power crystal oscillator. Your typical crystal oscillator circuit looks like this: simulate this circuit – Schematic created using CircuitLab Simplistically, the crystal (along with the 2 capacitors) provides a 180 degree phase shift at its resonant frequency and ...


6

10 Vpp is NOT the same thing as 10 Vrms. In order to get the full output from the transducer at 10 Vrms, you're going to have to drive it with a 20 Vpp square wave, or a 28.3 Vpp sine wave. With a single supply and an H-bridge driver, you will need a 12 to 15 V power supply in order to get there. An alternative would be to build a relatively high-currrent ...


6

I would look at it from a different angle and try to detect in which slot the metal pin is placed. This is an easier task and could be done in several ways such as using proximity sensors or micro switches. These could be wired to a micro controller and thus you could detect the amount of weight blocks lifted. This is just an idea for a possible way ...


6

There are monostatic and bistatic ultrasonic transceivers. Monostatic Monostatic transceivers are single transceivers that do the transmitting and receiving. As long as the transmission stops before the reception starts, you can do measurements. The minimum distance that you can measure is limited in this configuration, but it's smaller and cheaper to ...


5

Try these linear amplifiers made by Apex. They are designed specifically for ultrasound aplications.


5

A standard piezoelectric ultrasonic transducer will not work efficiently at sub harmonics or harmonics - it's a 2nd order resonant mechanical device with high Q - there aren't different modes of operation as you might find with some crystals (for instance).


5

I'm not aware of cheap ultrasound sensors that can measure the Doppler in the return signal. At the risk of answering something that isn't quite what you asked do you need ground speed or is air speed sufficient? If you place two ultrasound sensors facing each other in line with the direction of travel and measure the range between them then you will get a ...


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