Embedded Files
Keysight EDU34450A DMM
Keysight EDU34450A DMM
DCV Accuracy
DCV Accuracy
By default, the instrument autoranges to select the range it thinks I need but this can be manually overridden (using the Range buttons [9]).
Notice: reduced accuracy at higher ranges.
Remember: always choose the range for maximum accuracy without overload
Voltage Measurement
Voltage Measurement
Voltages are measured across nodes in a circuit.
As such they are often measured in parallel with components, or at a point in the circuit with respect to ground.
An ideal voltmeter presents an infinite input impedance ( = no current flow ) across is terminals, so as to not disturb (load) the circuit under test.
Current Measurement
Current Measurement
Currents are measured flowing from a node in a circuit.
As such they are often measured in series with components.
An ideal ammeter presents an zero impedance between its terminals, so as to not add additional resistance to disturb the current flow in the circuit.
AC Measurement
AC Measurement
There are various ways to report the voltage of an AC voltage / current.
Peak-to-peak and peak are simple.
Average takes the average value of the waveform.
– >Since a sine wave has zero average value, AC voltmeters report the average of the absolute value of the waveform.
The root-mean-square (RMS) is a much more useful value.
(rms = heat power & energy transfer capacity of AC voltage & current)
-> The RMS value of a periodic signal 𝑣 is defined as
where 𝑇 is the period of the signal.
-> RMS is useful because the RMS voltage can be used to directly compute power using
->RMS was more difficult to determine in analog meters.
The EDU34450A is a “true RMS” DMM that implements the RMS calculation by digital sampling the signal and numerically implementing the RMScalculation.
Resistance Measurement
Resistance Measurement
Ohmmeters measure an unknown resistance 𝑅𝑥 accurately using what is known as a bridge circuit.
A Wheatstone bridge uses a precisely known set of fixed (𝑅1, 𝑅3) and variable resistor (𝑅2) resistors.
𝑅2 is varied until 𝑉𝐺 = 0, which can be done to extremely high precision.
Modern DMMs can precisely measure voltages and currents arising from stimulating the resistor with a precisely known current.
The measured voltage and current can be used with Ohm’s Law to calculate the unknown resistance.
For precise measurements, the lead resistance can be eliminated using a 4-wire measurement
GDM - 8145 DMM
GDM - 8145 DMM
Page updated
Google Sites
Report abuse