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→Digital Multimeter
The DC V function will measure a DC voltage (e.g. DC power supply). The AC V function will measure an AC voltage (e.g. function generator). The Ω function will measure real resistance (e.g. potentiometer). The Freq function will measure the frequency of an AC voltage signal from 5Hz through >1MHz. The AC+DC function will measure the True RMS value of AC+DC voltages or currents (i.e. AC signals with a DC offset). See the user manual for more info. The Diode function will measure the forward voltage drop of general-purpose diodes and Zener diodes.
The DC V function will measure a DC voltage (e.g. DC power supply). The AC V function will measure an AC voltage (e.g. function generator). The Ω function will measure real resistance (e.g. potentiometer). The Freq function will measure the frequency of an AC voltage signal from 5Hz through >1MHz. The AC+DC function will measure the True RMS value of AC+DC voltages or currents (i.e. AC signals with a DC offset). See the user manual for more info. The Diode function will measure the forward voltage drop of general-purpose diodes and Zener diodes.
For the functions in blue... The DC I function will measure DC current. Don't ask why the electrical engineers decided to use the variable "i" for current. It's complicated. The AC I function will measure AC current. Do not attempt to measure the AC current from a wall outlet; you will blow something up (potentially including yourself). The Continuity function (that looks like three sound waves) will deliver an audible beep when the probes sense less than 10Ω between them. The purpose of this function is to test the quality of various connection points in your circuit. It can answer questions like... Is this a good solder joint? Are these two components joined at the same node? Is this point in the circuit connected to ground? Did I accidentally fry this component? The Continuity function is an invaluable troubleshooting tool that allows you the freedom to poke around in your circuit to see if everything is connected like it's supposed to be. In most cases, you should have all source voltages turned off when you are testing continuity. The Period function will measure the time period of an AC voltage signal from 0.2s through <1μs.
For the functions in blue... The DC I function will measure DC current. Don't ask why the electrical engineers decided to use the variable "i" for current. It's complicated. The AC I function will measure AC current. Do not attempt to measure the AC current from a wall outlet; you will blow something up (potentially including yourself). The Continuity function (that looks like three sound waves) will deliver an audible beep when the probes sense less than 10Ω between them. The purpose of this function is to test the quality of various connection points in your circuit. It can answer questions like... Is this a good solder joint? Are these two components joined at the same node? Is this point in the circuit connected to ground? Did I accidentally fry this component? The Continuity function is an invaluable troubleshooting tool that allows you the freedom to poke around in your circuit to see if everything is connected like it's supposed to be. In most cases, you should have all source voltages turned off when you are testing continuity. The Period function will measure the time period of an AC voltage signal from 0.2s through <1μs. The dB and dBm functions are part of the math options and can measure the gain of a circuit. See the user manual for more info.
===Plugging In The Leads===
===Plugging In The Leads===
It is very important that you plug in the leads (cables, banana jacks, whatever you want to call them) into the correct terminals to make your measurement. The correct input terminals can change depending on what type of measurement you are performing. Failure to choose the correct terminals and set up the measurement properly can result in a blown fuse, damage to the digital multimeter, damage to another benchtop instrument, and/or damage to your circuit. So... read what each terminal is meant for before you start plugging things in willy-nilly.
It is very important that you plug in the leads (cables, banana jacks, whatever you want to call them) into the correct terminals to make your measurement. The correct input terminals can change depending on what type of measurement you are performing. Failure to choose the correct terminals and set up the measurement properly can result in a blown fuse, damage to the digital multimeter, damage to another benchtop instrument, and/or damage to your circuit. So... read what each terminal is meant for before you start plugging things in willy-nilly.
The black COM terminal is either connected to ground or to the lower-voltage side of whatever you are measuring. It depends on what you are measuring.
The red terminal labelled with "V Ω Diode Hz Continuity" is used for all voltage, resistance, diode, frequency/period, and continuity functions described above (including the voltage measurement for AC+DC).
The two red terminals labelled 20A and 500mA MAX are used for all current functions described above (including the current measurement for AC+DC). Basically, the 20A terminal is for higher currents, and the 500mA MAX terminal is for low currents. If you're unsure of how much current you'll measure, always start with the 20A terminal first. Then, only switch to the low current terminal if the amperage is well below 500mA.
====How To Measure With The Leads====
All voltage, resistance, diode, frequency/period, and continuity functions can be measured in parallel. For example, if I'm measuring a voltage drop across a resistor in my circuit, I don't need to alter the circuit in any way. I can simply connect the black COM terminal to the lower-voltage side of the resistor (maybe it's at ground potential... maybe it's not) and connect the "V Ω Diode Hz Continuity" terminal to the higher-voltage side of the resistor. This is a parallel measurement. For the resistance and diode functions, it's usually best to measure these components separate from the circuit to ensure that other circuit components do not influence the measurement (such as other resistors in parallel). If you're soldering up a PCB, measure the resistor's value <strong>before</strong> soldering with the resistor completely separate from all other components. If you're using a breadboard, turn off all source voltages (because you would always do this before physically altering your circuit, right???) and pop the resistor out of the board to measure it.
All current functions must be measured in series. This means you must choose an injection point in your circuit, break the electrical connection between the components, and connect the digital multimeter leads in a way that bridges the connection between the components. This is a series measurement. If you just made a voltage measurement and you are about to perform a current measurement, this requires several steps. First, turn off all source voltages. Second, disconnect the digital multimeter leads from the circuit. Third, swap the lead from the "V Ω Diode Hz Continuity" terminal to the 20A terminal. Fourth, alter your circuit so that you can insert the digital multimeter leads in series at your desired injection point. Fifth, turn the source voltages back on.
==Common Ground==
==Common Ground==
Ground (sometimes called neutral or earth) is usually at 0V. Ground acts a reference point for most electronic circuits.
Ground (sometimes called neutral or earth) is usually at 0V. Ground acts a reference point for most electronic circuits.