List of what you can use:

JOYO mini Amp (I payed 9€ for it)
Telephone pickup coil (I payed 2€ for it)
3.5mm mono male jack to 6.3mm mono female jack adapter (I had this already)
3.5mm mono female female jack (I had this already)
9V battery
a stick
pink tape
some wire

Why didn't i buy a female 3.5 to female 6.3 ?
I think this doesn't exist, I couldn't find that, and i already had one adapter.

There is a new version of the Esmog Spion on the market:
https://www.esmog-shop.com/messtechnik/endotronic/

In my boiler video you can see more measurements with the "Buzz stick":
https://www.youtube.com/watch?v=5FtjW6KnHOQ

Music:
Marty Gots a Plan Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
http://creativecommons.org/licenses/by/3.0/