What is the minimum output impedance a Digital Multimeter should have when testing computer-controlled systems?

When testing computer-controlled systems, a digital multimeter should have a minimum output impedance of 10 Megaohms to ensure accurate measurements. High input impedance is crucial in such circuits because it minimizes the loading effect on the system being tested. If a multimeter has low impedance, it can draw significant current from the circuit, altering the voltage and potentially leading to erroneous readings.

In modern computer-controlled systems, which often operate at lower signal levels, having a high input impedance, like 10 Megaohms, allows the multimeter to measure voltages without affecting the actual operating conditions of the circuit. Therefore, the higher the output impedance, the better the multimeter can provide an accurate representation of the voltage levels without disrupting the system’s performance.

This is especially important when diagnosing issues in sensitive electronics where precision is vital. Lower impedance values, such as 1 Megaohm or 100k ohms, may not suffice for some components and could lead to misleading diagnostics. Thus, using a multimeter with at least 10 Megaohms output impedance is standard practice when working with these types of systems.