In 2019 I tried building my own spirit box.
Using the Mega gives quite good flexibility and also the ability to code what ever FM frequencies you want and in what order you want.
It was all linked up to a 2004 LCD display along with 2 thermistors for temp monitoring. All data was stored to an SD in an RTC format.
It worked great, I used it lots of times here at home on the breadboard and once out on location but as I did not receive anything after a couple of months I then decided to break it down.
So far this year I have lost some enthusiasm but I just need to try and get it back and I would be dead keen as I was a couple years ago if and only if I could actually get an EVP.
In a strange way, having had nothing I have to feel that EVP’s do not actually exist but so many people do get them. Maybe it’s just me and I don’t have the ability to receive EVP’s.