How Do Ultrasonic Distance Sensors Work? -- The Learning Circuit 85

Most of my practical experience with the sensors was just making these videos, so I may not be the best person to find the right model sensor for your project. However, if you post more details about what your project is and the parameters it entails, someone may be able to help you.

Hi Karen,

Thank you very much for that intresting video. Could you help me with your exprience, I have a project involve ultasonic divice .. but i cant find the right sensor..

There aren't that many latin + greek letters to have a single letter for each constant or variable, so of course you have to "recycle" them. The lowercase c is also commonly used for specific heat for instance.

Hi Karen,

Very interesting topic as always, thank you very much. I won’t miss the next project.

I checked my physics books and c is always speed of light.

When I looked up speed of sound they used v or Vs.

So my US text book did not follow the Oxford definition, probably like me, they found it too confusing with the speed of light.

FYI, when I did a project with the Noise and Sonic Boom Information Technology office in the US Air Force, I never saw the speed of sound referred to as c.

DAB

Goodt stuff, Karen.

I worked with piezo electric transducers and 8048/49 chips in the 70s and 80s to produce marine echo sounders. Great fun!

At the time, I never thought about how they worked! It was somebody else's job to make the transducers!

Neil

I'm just going to jump in on this as well: In my experience, c is pretty common in aeronautical engineering and pilot-level aerodynamics as notation for the speed of sound at a given altitude. Even Mach numbers are defined as M = u/c where u is airspeed and c is the speed of sound at that density altitude.

"...So I do not know where wikipedia came up with that notation..."

Oxford Dictionary of Physics perhaps ?

https://www.oxfordreference.com/view/10.1093/acref/9780198821472.001.0001/acref-9780198821472-e-2875

"Symbol c or c_s. The speed at which sound waves are propagated through a material medium."

It is not a universally known notation as I never encountered it during my work career.

The speed of sound was usually given as a mach number with altitude.

c was always the speed of light.

So I do not know where wikipedia came up with that notation, but it was not part of my physics or engineering use.

DAB

Awesome Karen!

You were not even born, when I begged a ultrasonic pizoelectric transducers off of a manufacture to write a thesis project paper some 40 years ago. I begged because the cost of the device at that time was in the thousands of dollars. I was sent two for free, wrote my thesis, passed and got my shiny diploma.

Your video explains much of what wasn't common knowledge at that time. Again great material.