Here's an odd one for y'all. I have a Booz barometer. This is the old bartop game where you attempt to move a metal loop over a metal rod without making contact with the rod. It is powered by a 6v lantern battery. The problem with the game is that, when the battery is new, if you just look at the rod funny, the buzzer goes, the coil fires and the game ends. On the other hand, when the battery is towards the end of its life, you can pretty well keep it on the rod without the game ending. Sparks fly when you contact the rod, the buzzer sounds, albeit rather sickly, but the coil won't fire. Obviously, between those two scenarios, the game work well. However, that 'sweet spot' doesn't last long. Seems like it stays at the too sensitive state for a long time (lots of plays), and once it starts to deteriorate it goes fast. So, I thought I could wire a pot into the circuit to dial in the sensitivity while it is 'too hot'. My question is what type of potentiometer should I use? Or is there another answer? (Converting it to plug in is not an option)

It works fine, the issue is the sensitivity. That having been said I did have to replace the buzzer, so perhaps I need to find a larger one that requires more oomph, thereby increasing the overall resistance of the circuit. I was just thinking a pot would allow me to fine tune it.

I'm sure it would somewhat, but I was thinking a small resistance one might do the trick. I guess I should hook up my DC voltage regulator and see exactly where the sweet spot is. I know they make component linear DC voltage regulators; however, I have no idea if they would work for this sort of thing. Maybe that's a better way to go?

I have, obviously, not been very clear in my initial description of the situation. It works fine right now, it is simply too sensitive when a new battery is put in and it remains that way for a large number of plays. By too sensitive, I mean that if you barely brush the rod for a fraction of a second, the buzzer sounds, game ends. It is not staying on. Insert your nickle, the light comes on as it should. If you hit the rod with the ring, a second circuit is completed which activates the buzzer and a coil that drops the coin and ends the game. I need to increase the resistance of the circuit the rod is on so it is not activated with a slight brush against the rod. Hopefully, that makes more sense.

While that would work great, I don't want a cord/plug.

Thanks. So...recommendations on what specs for the cap?

Thanks I'll give that a try.