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Several consecutive experiments are described with a printed circuit boardPCB set-up, especially designed for these experiments. Doing the consecutiveexperimental tasks opens up possibility to determine the value of electroncharge $q_e.$ The fluctuations of the voltage $U(t)$ should be measured fordifferent illuminations of a photodiode. The voltage is amplified 1 milliontimes $Y=10^6$. The amplified voltage $YU(t)$ is applied to the device, whichgives the result of the value of the time averaged square of the voltage$U_\mathrm{S}=\left<(Y U(t))^2\right>/U_0$. This voltage $U_\mathrm{S}$ ismeasured with a multimeter. The series of measurements gives the possibility todetermine the $q_e$ using the well known Schottky formula for the spectraldensity of the current noise $(I^2)_f=2q_e\left<I\right>.$ For the junior highschool students, the basic problem is to analyze the analog squaring. Students'work is separated and graded in four categories S, M, L, XL divided by age ofstudents. For the last XL categories, the tasks contain problems oriented tophysics university education program and include theoretical research of thePCB set-up as an engineering device. This is the problem of EPO6, December 2018``Day of the Charge'' considered. EPO6 is organized by Sofia branch of Union ofphysicists in Bulgaria in cooperation with Faculty of physics of SofiaUniversity and Society of Physicists of Republic of Macedonia.

Measurement of the electron charge $q_e$ using Schottky noise. Problem of the 6-th Experimental Physics Olympiad. Sofia 8 December 2018