Finding water leaks using ultrasonic detector - PeachParts Mercedes-Benz Forum

donbryce · #1 02-18-2004, 07:51 AM

I was posting in another forum and found this tidbit, which describes a fancy apparatus that some shops use to find leaks. I thought it ought to be shared....

(I posted a question about how this procedure works)

"The basic principle is so simple that you're going to kick yourself when you think about it, as it's the same as what you suggested -- but reversed, kinda like filling the car with water and looking for the places where it leaks out. In this case, they fill the car with sound and look for where it leaks out.

The detectors are based on the assumption that energy, in this case sound, travels more easily through an opening -- in this example, the hole where the water's leaking in, and high frequencies leak out more easily through small openings than do low ones.

They don't have to be ultrasonic per se, but this offers advantages in that the higher the frequency, the more easily it can be blocked, and therefore it makes pinpointing the source easier. It also allows the equipment to be smaller.

Basically, there are two units: an ultrasonic generator that's placed inside the car, and a receiver with a probe that a tech outside uses like a stethoscope.

We can't hear ultrasound, so the receiver contains circuitry that converts it to the audible range, allowing the tech to use headphones to better block out extraneous noise while he searches.

This particular technique is also useful for locating miscellaneous noise sources, and the basics can be used as the foundation for a great many devices for other purposes -- including radio, radar, and sonar

As an aside, you can fairly easily build a receiver that'll let you listen to bats and miscellaneous insects. "

Anyone know how to 'home build' something like this? Sound great for those elusive windshield and sunroof leaks!