I have finally got a compass today and checked my transducers and small external computer speakers. All of them appeared to be the North Pole ones, as required for the zappicator.
So, I am playing with the transducer now. Will leave speakers for later. They were cheap and always can just order another set.
So, can you suggest what I should look for when using it on the body? I just need to find out ways to see whether it is working or not...