[Geo]

Originally Posted by hung

Geo, you can actually use many alternatives to it, not only the 555, but a 7555, a CD4001, etc. So what?
They alone, do not make a beeping circuit. You need a logical circuit to provide this once you fully understand what they are supposed to do. If you don't, you will only have a beeping trigger. That's all. This will be even harder to follow if mistakes are present in schematics.

To my surprise, you still appear to not understand what is going on to back up your conclusions which are mistaken.
An ion based detection system obviously will react to all kinds of electric fields as ions are everywhere. But the way the Mineoros are built allows it to 'classify' the gold ones.
This machine is about 10 years old now and despite of being good at that time, the new models are different, both in terms of circuitry and ionic chamber.
But, as with any electronic apparatus, it can always be improved, as long as you understand the concept and what is going on.

From a metaphoric view, you are trying to 'listen to the answer' to figure out the question made.
In some instances, you may deduce what it could be, but in others, you will not know what exactly was asked if you did not hear the question yourself. And this is what it takes.

Why you try to present that you did not understand what I said???. I am sure that you understood.

Regards