For those who see similar readings on silicon transistors on the k-firmware, which is incorrect (upper left corner). This is not a program error, but an incorrect measurement scheme. If we add inductance and capacitance to the scheme, highlighted in red SMD, we get correct readings for silicon transistors. For germanium transistors, measurements are shown - lower right corner.
Also recommended by the ATmega's datasheet, i.e. a small inductor plus cap for the ADC's power supply.
Here is a reply from Karl-Heinz Kübbeler on the advisability of using a inductance(throttle-coil) in the AVCC power supply circuit:
"There is no need to use a throttle (coil) for the AVCC supply.
During the ADC period no digital activity disturb the VCC power supply.
Any inductance in the AVCC supply also have a resistance.
The influence of the resistance of the coil probably interfere the
measurement result more then a remaining noise at the VCC power.
The enhancement of ADC resolution requires a noisy or unstable signal.
The mean value of several input values is always the input value itself,
if there is no change of the value. Only if the input signal changes a
little bit, the mean value can interpolate the steps of the ADC by
a statistically effect. For example the mean value of
10, 11, 11, 12, 11, 10, 11, 10, 11, 11 is 10.8 ! "