Hi David,
I tried this setup. We get the clicking and associated light flashing with Vin to Vout, but when polarity is reversed, there is no clicking nor flashing.
So you are saying that the pot should work when the current reverses flow? if current flow starts in the direction of Vin to Vout, which works, then changes direction flowing from Vout to Vin, it should flow in this direction?
The speaker works in both polarities, but when the Pot is added, it only clicks in one polarity