Ultra Sonic tapemeasure

[Purple Rabbit]

For my last A level project i am attempting to biuld an ultra sonic tapemeasure using mainly CMOS chips and pretty basic equipment, can it be done?!?

My idea is to have an transmitter and reciever and clock the time it takes for the wave to reach the transmitter. This seems to be the simplest way of doing it (rather than using echoes etc) but i am still unsure about what frequencies/distances i should use, as well as how fast the clock should be.

Any hints/tips/ideas would be most welcome, especially if someone has done it with CMOS and knows that it can be done!

thanks

 

[Super_voip]

Why not buy an ultrasonic tapemeasure, I bought one recently for $15, and find another use. The one I have has a "test" pin inside at which the raw unmodulted signal is available, and as soon as I get a clear spot on my bench, I'll investigate further. I already have the test point extended to a socket mounted in the case. If you do need to build your own what equipment do already have ie transducers? as the transducers determine the operating frequency. For the two transducer approach try a Polaroid setup.

 

[Hero999]

You can buy ultrasonic proximity detectors that output a signal from 0 to 10V depending on the distance of an object. I imagine that it'd be quite easy to make a tape measure by adding a microcontroller and LCD display.

 

[Purple Rabbit]

update!

Thanks for the ideas, especially the tip about the test pin, that could come in handy! I now have access to ultra sonic signal generators as well as a transmitter and reciever. Transmitting at 40kHz i can pick up a signal up to 1.5m away, and i am working on getting a fast enough clock speed to time it!

Thanks again



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