What multimeter features should I consider for my circuitry projects?

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Discussion Overview

The discussion revolves around the features to consider when selecting a multimeter for circuitry projects, particularly for an engineering student with a budget of $200. Participants explore various functionalities, including measurement accuracy, power supply capabilities, and the distinction between different types of multimeters.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants suggest that most multimeters can measure voltage, current, and resistance, but measuring resistance with high accuracy (e.g., milliohms) may not be feasible with affordable handheld models.
  • There is uncertainty regarding the request for a multimeter that can "plug into a regular electrical socket," with some questioning whether this refers to AC power or the ability to measure AC voltages.
  • One participant mentions that a multimeter is typically not expected to function as a power supply, suggesting that a separate power source would be more appropriate for providing a specific voltage.
  • Some participants highlight that True-RMS meters are more expensive but may be necessary for accurate measurements of non-sine wave signals, while others argue that standard meters suffice for typical AC power measurements.
  • A few participants express the need for a multimeter that can output current to a circuit, with one noting that such devices tend to be significantly more expensive.
  • Suggestions for shopping include looking for autoranging digital multimeters and considering online retailers that ship to Canada.

Areas of Agreement / Disagreement

Participants generally agree on the basic functionalities of multimeters but express differing views on the necessity of certain features, such as the ability to act as a power supply or the need for True-RMS capabilities. The discussion remains unresolved regarding the best approach to meet the original poster's requirements.

Contextual Notes

Participants note limitations in the capabilities of affordable multimeters, particularly regarding high-accuracy resistance measurements and the expectation of multimeters to serve as power supplies. There is also a lack of consensus on the necessity of True-RMS functionality based on the user's specific applications.

The Sand Man
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Hello Everyone,

I'm an Engineering student who has had the opportunity to work on some Mechatronics. Ever since, I've been interested in working on some circuitry for my own projects. Unfortunately, I don't have much knowledge about brands and prices, but I am looking for something that has these features:

  • Accurate to at least the milli-*insert unit*
  • Can plug into a regular electrical socket
  • Can output its own current into a circuit
Are my demands able to be met with the maximum of a $200 budget?

Cheers,
Sand
 
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Any multimeter can do the first two (except measure resistance with an accuracy better than 1 mili-Ohm; which would be pretty pointless with a handheld multimeter anyway; which is what I assume we are talking about here).
I am not sure what you mean by the third? Current for measurement of current to drive something?

The main "technical" difference between cheap multimeters and and more expensive ones is the latter areTrue-RMS. More expensive ones are also usually more rugged and might have extra functions (e.g. the capability to measure capacitance, transistors etc); some can also be connected to a computer to download data.
 
f95toli said:
Any multimeter can do the first two (except measure resistance with an accuracy better than 1 mili-Ohm; which would be pretty pointless with a handheld multimeter anyway; which is what I assume we are talking about here).
I am not sure what you mean by the third? Current for measurement of current to drive something?

The main "technical" difference between cheap multimeters and and more expensive ones is the latter areTrue-RMS. More expensive ones are also usually more rugged and might have extra functions (e.g. the capability to measure capacitance, transistors etc); some can also be connected to a computer to download data.

Well, the ones we used in the lab had a feature where connecting a resistor to the leads gives you a reading of what resistance the resistor provides...Without connecting a battery or anything. They were the stationary desktop ones. It was a useful multimeter because we could power a circuit with a few LED lights and sensors without having a battery in the circuit.

Cheers,
Sand
 
Virtually every multimeter has the ability to measure Resistance. The term MULTI, implies multiple functions. Every handheld Multimeter can measure, Voltage, current and resistance.

Not sure what you mean by "plug into the wall" do you want a AC powered meter? Or one that can measure AC voltages? Not sure why you would want the former as a handheld battery powered meter is more useful, for the latter, it is an expected function of a multimeter.

Measuring milliamps and millivolts is in the expected ability of any Multimeter, milliohms on the other hand requires special instrumentation and is not found on affordable multimeters. Not a big deal however because that is not a common need.
 
Integral said:
Virtually every multimeter has the ability to measure Resistance. The term MULTI, implies multiple functions. Every handheld Multimeter can measure, Voltage, current and resistance.

I know that.
Integral said:
Not sure what you mean by "plug into the wall" do you want a AC powered meter? Or one that can measure AC voltages? Not sure why you would want the former as a handheld battery powered meter is more useful, for the latter, it is an expected function of a multimeter.

One of the projects I'm looking to undertake is related to recharging standard batteries. I want to look at manufacturer specifications and see how they compare to the ones that I recharged. You can understand why a multimeter with the ability to output a maximum of 2 Volts would be useful. I want it to plug into a regular electrical socket because using a hand-held multimeter powered by batteries to recharge batteries sounds silly.
Integral said:
Measuring milliamps and millivolts is in the expected ability of any Multimeter, milliohms on the other hand requires special instrumentation and is not found on affordable multimeters. Not a big deal however because that is not a common need.

Everybody forget about milliohms, I definitely don't need to measure anywhere near that accuracy.

Here is more or less what we used in our lab:

8845a_DMM.JPG


Where should I be shopping for one of these?

Cheers,
Sand
 
I would not recommend buying test equipment based on the needs of a single lab. A multimeter is something that you wll use over and over in many different situations.

Most people do not expect their multimeter to double as a power supply. If you need a 2V source get a power supply to fill that need and use the multimeter do perform the measurements.
 
Integral said:
I would not recommend buying test equipment based on the needs of a single lab. A multimeter is something that you wll use over and over in many different situations.

Most people do not expect their multimeter to double as a power supply. If you need a 2V source get a power supply to fill that need and use the multimeter do perform the measurements.

Fair enough, I'll heed your guidance!

So, what are some standard power sources? I don't want to use AA batteries, is there anything with greater output and longevity and easy ease of recharging?

Other than Radio Shack, are there any good online dealers and suppliers who ship or sell to Canada?

Cheers,
Sand
 
Google "bench power supply"

Find one that meets your need.

or You could put something simple together using an old appliance power supply, all depends on what you can spend and/or are comfortable with fabricating.
 
  • #10
If you need a meter that will supply a current to a circuit (a current source), along with the other "normal" functions of a multimeter, you will be looking for a something with calibration capabilities like the Fluke 789. But, for something like that, you'll be paying in excess of $800.

Even a dedicated loop calibrator like the Fluke 707 will cost you more than $600.

As for True-RMS. If you're going to be dealing strictly with sine wave signals (typical AC power, for example), you won't need true-RMS capabilities; standard meters calculate the RMS value based on the assumption that you are measuring a perfect sine wave. However, if you need more accuracy or the ability to measure sawtooth, square, or other AC signals, then pay the extra money for a true-RMS meter.

There are many true-RMS meters that run for under $200.
 

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