The OML-2M portable oscilloscope, old ussr gadget.

Description

The OML-2M portable oscilloscope was originally intended mainly for novice radio amateurs. But its characteristics are in many ways not inferior to quite professional oscilloscopes and allow you to perform almost all measurements.
Technical characteristics of the OML-2M oscilloscope
The duration of the investigated pulse: from 0.1 μs to 0.1 s, swing from 10 mV to 300 V;
The frequency range of the observed periodic signals: from 3 Hz to 5 MHz [3];
Amplitude of the investigated signals: from 10 mV to 150 V;
Measured time intervals: from 0.4 μs to 0.2 s;
The error in measuring the amplitudes of pulse signals in the range of their variation from 20 mV to 150 V is no more than 15%.
The error in measuring time intervals in the range from 0.4 μs to 0.2 s with the horizontal image size from 4 to 6 divisions is no more than 15%