This illustration of a handsome crystal set listening post comes from 90 years ago, in 1928 issue number 1 of Радиолюбитель (Radio Amateur) magazine, illustrating an article by A. Pushkov.

Elsewhere in the magazine, it’s apparent that, just like their Western counterparts, young Soviet experimenters discovered the fun that could be had with a milliammeter, although I have to admit that I never thought to conduct the second and fourth experiments shown here:

(The piece of metal in the above diagram is marked “железо”, iron.)

The sensitive galvanometer was probably a valuable instrument in the 1928 Soviet Union.  Modern students desiring to reproduce these experiments can do so very inexpensively with a digital voltmeter such as the ones shown here: