Hire a professional that is insured. Don't risk your home to some self brewed solution.

 

Recall that the originator was asking about a listening device. A down-converting audio system can certainly do that. And a CD4066 quad analog switch can serve much better than a diode bridge mixer at the frequencies of interest. Use a 555 oscillator at twice the desired conversion frequency and then a CD4013 FF to provide a 50% duty cycle for the mixer, with the square wave doing the switching and the analog signal being switched and low-pass filtered so that the average value remains. For a microphone, either an electret with ultrasonic frequency response or a TV acoustic remote control microphone from way back when TV remotes were ultrasonic. The total cost should not be much.

 

Could a superhetrodyne hi freq audio device be made to produce a human hearable sound to make detection easier/reliable.

I think TS was asking IF audio based systems were easier/reliable......


Regards, Dana.

 

Hi all,
As somebody else mentioned, you can hear white ants munching on the timber. With a large infestation,it is so loud you can hear it at night when it is quiet. A simple high sensitivity amplifier and headphones will do the job as the human mind can determine the type of noise.
Trained dogs smell them.
The other option (and what found them in the house we were in) is heat. A thermal camera shows a nest quite clearly.