This device is useful as a proof of concept. I assembled it and then tested it and all I heard was a faint white noise that changed vaguely around an EMF but it had to be very close and even then it was not easy to tell if it was just random. I then thought maybe I put the chip in backwards, well I hadn't but when I reversed the chip it fried it and now I have a device that really doesn't work. Other than that the quality of the component seemed very good.
Response from The Curious Electric Company | May 11, 2017
Thanks for the review. Yes - it does need to be very close to the cable/device to detect (basically the sensors need to tocuh the cable/device). I'll update the info to say this. I've had pretty good volume/output from this but very variable with the source - old AC power supplies are very loud, phone backlight power supply is quite feint, but audiable when close to the front of the phone. You can improve the sensitivity with a larger hand wound inductor. Its based on the ElektroSlutch and they ahve plans for hand wound sensors: https://lom.audio/product-category/elektrosluch/ If you'd like me to send another IC then I can put on in the post to you. Regards, Matt