Electronic Basics #1: The Multimeter

Summary

This video explains how to use a basic multimeter to measure essential electrical parameters: voltage, current, and resistance. It covers the key features of a multimeter, including the use of probes, understanding Ohm's law, and performing continuity tests. The tutorial provides clear instructions for measuring voltage (DC and AC), resistance (with simple examples), and current (with necessary safety precautions). Viewers are guided step-by-step on how to safely and effectively use the multimeter, including common troubleshooting tips. The video is a practical guide for beginners to understand basic electronic measurements.

Takeaways

• 😀 A multimeter is an essential tool for measuring voltage, current, and resistance.
• 😀 Ohm's Law defines the relationship between voltage, current, and resistance, which is key for understanding electrical circuits.
• 😀 Multimeters have probes that are used to measure electrical parameters, with the black probe always connecting to the common socket.
• 😀 Measuring resistance is straightforward by connecting the probes across a resistor, but results can be inaccurate in a circuit due to parallel resistance paths.
• 😀 Continuity testing on a multimeter allows you to check for cable breaks by emitting a beep when there’s a near-zero resistance between the probes.
• 😀 Voltage can be measured in parallel by connecting the red probe to the positive side and the black probe to the negative side of a power source.
• 😀 Direct current (DC) is commonly used in circuits powered by batteries and power supplies.
• 😀 Always be cautious when measuring voltage inside power supplies as AC becomes DC there, and it can be dangerous if mishandled.
• 😀 Measuring current requires changing the position of the red probe to the 10 amp socket and opening the circuit to allow current to flow through the multimeter.
• 😀 The 10 amp socket is used for high current measurements, while the lower current socket should not be used for currents above 500 milliamps to avoid blowing the fuse.
• 😀 If your multimeter stops working when measuring current, check the fuse and replace it if necessary.

Q & A

What are the fundamental electrical variables described in Ohm's law?

The fundamental electrical variables described in Ohm's law are voltage, current, and resistance.

How does Ohm's law relate voltage, current, and resistance?

Ohm's law states that resistance equals voltage divided by current, or alternatively, voltage equals resistance multiplied by current, and current equals voltage divided by resistance.

What is the purpose of a multimeter?

A multimeter is used to measure important electrical parameters such as voltage, current, and resistance.

What do the probes in a multimeter do?

The probes in a multimeter are used to measure electrical parameters. The black probe is always connected to the common socket, and the red probe is used for measuring voltage, current, and resistance, with the exception of current measurement which requires a different socket.

How do you measure resistance using a multimeter?

To measure resistance, you select the Ohm sign on the multimeter, connect one probe to each side of the resistor, and read the resistance value displayed.

Why might measuring resistance in a built circuit fail?

Measuring resistance in a built circuit often fails because current follows the path of least resistance, and thus, the measuring current may flow through other components, leading to inaccurate readings.

What is the continuity feature on a multimeter used for?

The continuity feature on a multimeter is used to check if there is almost zero resistance between two points, which is indicated by a beep. It is useful for detecting cable breaks or ensuring connectivity in circuits.

What is the difference between measuring alternating current (AC) and direct current (DC) on a multimeter?

When measuring voltage, it is important to distinguish between AC and DC. Most common household or battery-powered devices use DC voltage, whereas AC voltage is used in power supplies. The multimeter settings need to be switched accordingly for accurate readings.

What precautions should you take when measuring voltage with a multimeter?

When measuring voltage, always connect the red probe to the positive side and the black probe to the negative side of the power source. Ensure the power is off when connecting to avoid electrical shocks.

How do you measure current using a multimeter?

To measure current, you need to open the circuit and place the multimeter probes in series with the circuit. Ensure the red probe is inserted into the correct current socket, usually a 10A socket for high currents, to avoid blowing the fuse in the multimeter.

Why should you start with the high current socket when measuring current?

Starting with the high current socket is important because the lower current sockets are designed to handle lower currents (up to 500mA), and using them for higher currents can cause the multimeter’s fuse to blow.

What should you do if your multimeter fuse blows?

If the fuse in your multimeter blows, you should unscrew the multimeter, locate the blown fuse, buy a replacement with the same value, and replace it before using the multimeter again.