duldul123:
Hi ,
I was trying to use the toneAC library to produce ultrasound in the 20kHz range. Firstly, the library works brilliantly and thank you for that.
The only issue that i have been having is that sound isin't loud enough. I was using a standard 4 ohm buzzer and the sound output coming from it dosnt seem to be loud enough.I tried using an Amp LM386 circuit to amplify the output .. described here http://web.mit.edu/6.s28/www/schematics/lm386.htm
But i then had to resort to use one of the 2 pins(9 or 10) which brought the clicking soung back. I have an Atmeg168.Any you help me figure out how can i raise the output volume. I want t be able to detect the sound in a range of abt 10 m.
Lastly, Im fairly new to this
Humans can't hear well in the 20kHz range. Also, many transducers don't produce much at that frequency either. You would need an ultrasonic transducer designed for that range as well as a SPL meter to actually measure the sound output in that frequency range. Basically, you need a different transducer and a different way to measure the volume (not your ears).
As far as the transducer, something like the PROWAVE - 250ST180 would work well, that's what I use. Keep in mind, when you're creating a 20-25kHz sound, humans can't hear it at all. So, while it may be able to output 105dB you won't be able to hear it at all.
To measure the volume at ultrasonic frequencies, you'll need a SPL meter. Depending on your age and how many concerts you've gone to, the max you may be able to hear is probably in the 15kHz to 17kHz range. Here's a Digital Sound Level Meter. But, you can get older models on eBay for cheaper.
Hope that helps!
Tim