Help find physical meaning

Question

Electronics

Gentlemen, please tell me the principle of operation of a wonderful device that fell into my hands a few years ago. This is an illuminated glass from Ephesus. When you touch it with your hand, a beautiful blue backlight turns on. It has been working for me for a long time, but new ones have not been sold for a long time. I thought I could do something similar with an ordinary glass, but the trouble is I don’t understand the principle of operation.

It is clear that the LED is shining, but how does it turn on? The first thing that comes to mind is the capacitive effect, but the backlight turns on when touched even when the glass is filled with water! Given the very high dielectric constant of water, the filling of the glass should have a stronger effect on the capacitance than touching.
Maybe he's picking up leads? But glass is a wonderful insulator. Did the manufacturer go to cover it with a metal nanofilm. Doubtful. So how does it work, anyone have any ideas?

Answer 1

Googled it here :

Modern field-effect transistors are very sensitive, and if the base of the transistor is connected to the surface of a glass, then the negligible current flowing from a person to a glass is already enough to open the transistor. It remains to slightly refine the circuit to eliminate accidental operation (detune from possible pickups of the electric field of the 220 volt network on the glass, and also carefully isolate the bottom to prevent current from draining from the table surface to the glass) and voila - the glass accurately determines the touch of a person. From the point of view of a field-effect transistor, huge currents flow from a person, so it is easy to detune from pickups and distinguish a person from other objects.

On my own behalf, I’ll add that although glass is an excellent insulator, elementary charges can accumulate and drain on the surface. The inner surface of the glass is most likely isolated from the outer one, and in fact the glass should sometimes glow even without being touched if there are drops of water on it, for example, after washing.
And about the fact that they have not been sold for a long time, I even found a whole company that deals with luminous glasses in all sorts of variations.

Answer 2

Read the history of the Leyden jar , if you take a glass with your hand, then you are the guide.
And my daughter also had a similar “musical” glass - there was a light sensor at the bottom, it worked when you lift it.

Answer 3

Perhaps it is powered by 50Hz industrial mains induction.