How to measure the current of a circuit with a multimeter.
Video and Diagram:
More detailed Diagram
Measuring simple circuit current video
Goes with diagram.
Power supply I use in my videos.
I am only covering digital multimeters on this page, as analog meters are rare these days.
- As a general rule, don’t measure power supply current directly. Something must limit the current. However, some weak power supplies, such as small solar cells, can be measured directly if the expected maximum current is well below the maximum current setting of the meter, and won’t damage anything else.
- Open up, or find an open part of the circuit (such as an open/off switch). I like to measure the terminals of an open/off switch that is part of a circuit to measure how much current flows when the switch is closed.
- Make sure the meter is set to be able to measure more current than you can expect. Too much current going through the meter for a particular setting will likely blow an internal fuse.
- Connect the probes to the points that you want to measure the current at and read the current on the display.
Other basic electronics topics that you should know before moving on to more advanced topics.
- Electronic component appearance and schematics – Commonly used through hole versions
- Electronic circuit basics
- Voltage sources for electronics basics
- Multimeter measuring voltage
- Resistor component – Learning electronics resistors
- Light Emitting Diodes – Indicator LEDs
- LED circuit -Lighting a Light Emitting Diode
- Resistor limiting current – Ohms law
- Multimeter measuring current
- Wattage – Electrical Power unit
- Resistors connected in parallel
- Series resistors
- Voltage divider – Setting a fractional voltage
- Resistor color code
- Diode – Rectifier
- Trimpot – Trimmer potentiometer – Voltage divider – Variable resistor
- Capacitor component
- Capacitor RC time constant
- Voltage ramp Demonstrated using a capacitor.
- LM334 three terminal adjustable current source not a common component. I use for an easy current source in many circuits.
- Switch NOT logic gate – digital signal inverter
- Switch OR gate – LED circuit
- Switch AND gate – LED circuit
- Switch based NAND logic gate – LED demonstration circuit
555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.
- 555 Timer IC This particulars of this integrated circuit covered on this page make a lot more sense after you study the basic circuits that follow.
- 555 timer bistable mode – Flip flip basic circuit
- 555 timer monostable mode – One shot
- 555 timer astable multivibrator mode – Flashing LEDs
- 555 timer schmitt trigger logic inverter – NOT gate
- 555 timer LDR controlled astable multivibrator mode LED flasher circuit
- 555 timer – Buzzer output – Astable multivibrator mode – Light dependent resistor LDR controlled circuit
Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.
- NPN BJT switch circuit – Bipolar Junction Transistor – 2N3904
- PNP BJT switch – Bipolar Junction Transistor – 2N3906
- NPN BJT emitter follower circuit – transferring a voltage minus a diode drop
- PNP BJT emitter follower circuit – Transferring weak signal voltage with a diode voltage shift
- NPN BJT current source – Bipolar Junction Transistor – 2N3904
- PNP BJT current source – Bipolar Junction Transistor – 2N3906
- Schmitt trigger – NPN BJT
- Zener diode component – voltage reference – regulator
- Voltage doubler circuit fragment- Capacitor charge pump – Some V loss
- 7805 5V positive voltage regulator IC
- Battery voltage state of charge SOC – From fully charged to discharged
These pages are still being compiled.