Fab Lab Rwanda · Group work
Input Devices
Our existing lab media show an MQ-series sensor module, oscilloscope recordings and multimeter measurements. We preserve those records below and distinguish what is visible from what needs a known probe connection and stimulus to interpret.
Module and instruments
The module image labels VCC, GND, DO and AO. AO denotes an analog output; DO is a digital output on the illustrated module. The exact sensor and circuit must be identified before assigning an allowable voltage or interpreting its response. The photograph alone does not establish the sensing element's part number.
The oscilloscope front panel identifies an RS Pro IDS-2202E. The meter image shows a UNI-T digital multimeter. Neither instrument's presence alone establishes which module pin was measured.
Oscilloscope records
The clips retain the original lab recordings. Their filenames are not enough to identify AO or DO. A smooth periodic waveform should not be described as a digital switching result without confirming its source, connection and scales.
Multimeter records
The multimeter is useful for steady voltage observations. Its update rate can hide short pulses, so it complements the oscilloscope rather than replacing the time-domain measurement. The retained photograph and clips should be interpreted with the actual probe pin, reference and operating condition.
Interpreting analog and digital measurements
For a repeatable comparison we will identify the board, supply and sensor, then map the meter probes and scope channel to AO or DO and the shared reference. We will record attenuation, coupling, vertical scale, time base and trigger with each scope capture.
Analog measurements should compare a stable baseline with a documented change in the input condition. Digital measurements should establish both logic states and the transition condition. A gas-sensitive module's output voltage is not a gas concentration measurement without the correct calibration and test conditions.
Our conclusion will relate the observed waveform and meter reading to that same condition, and explain why a steady voltage reading and a time-varying trace can describe different aspects of one signal.