Hi Bob,

Thank you for the very detailed pictures, it all becomes clear how the contacts and magnets interact.

Concerning your 9V battery block. This is a great idea to use a polymer battery and booster converter. Indeed, as you mentioned, the booster can cause interference in audio circuits like amplifiers and radios. A suitable coil in series with the output and capacitor across the output terminals might reduce this. Experimenting is the key to success!

Concerning the speaker block, I measure a DC resistance of 28 Ohms.

So, care must be taken if we design a circuit using this speaker. Check the experiments published here on the forum how this could be done.

Wish you all the best and a good health