Voltage meter

One day when I was browsing the forum and saw someone asking about turning signal into power, I thought, can I do it in reverse? And it turns out to be this.
Lower parts on the breadboard is for generating test inputs. There are 5 types of test signals: manual, sine, sawtooth, inverted sawtooth and pulse with adjustable duty cycle.
New signal filter used.

A - next test signal
D - previous test signal
Z - manual / frequency
X - duty cycle of pulse