Tutorial Discussion - Analog vs Digital Meters

[Save Old Iron 1,573]

This area will be opened for discussion on the benefits / advantages of Analog versus Digital meters.

The responses in this section will be used to help develop the tutorial for BASIC MULTIMETER TROUBLESHOOTING

This is not the tutorial - this is the post that will allow commentary on the tutorial and generate topics that will be discussed within the Multimeter tutorial.

Sure, let us know what style or styles you have and most importantly

Give a reason why you prefer one meter style over the other.

This will help folks who are getting ready to purchase a meter the benefit of your experiences.

Try to keep the comments centered around use of the meter for troubleshooting a garden tractor . Comments like "an analog meter is not affected by high RF fields" or "you can plug in an adapter to measure 50KV AC volts" are not going to be of interest to the person with a bad charging system on their tractor.

So this is it folks. This is where the pre-tutorial discussion begins.

Let's have some fun and see where this takes us.

[MikesRJ 558]

How to Choose Analog and Digital Multimeters

Nov 20, 2009 : Yuen Kit Mun

(Original article located here: http://home-electrical.suite101.com/articl...tal_multimeters )

Analog Multi-meters:

Old-style analog moving-needle multi-meters have significant advantages and a few drawbacks.

Advantages:

* Can measure fluctuations and transients. Analog meters can also measure low frequency fluctuations, to a certain extent.

* No batteries required. Batteries are needed for the resistance meter but the voltmeter and ammeter will work without batteries.

* Good for quick readings. The analog needle reacts quickly, making it suitable for fast probing of multiple points. High, medium and low readings are easily seen with a glance at the needle.

* Good for tuning electronic circuits to a specified value (example: setting a trim or variable resistor) as the needle's speed and relative position provides useful feedback.

Disadvantages:

* Limited accuracy. Accuracies range from plus or minus 1% to 4% of full scale (depending on the model and the type of measurement). A reading in the middle of the scale (half full scale) will have half the accuracy (2% to 8%).

* No auto-ranging. For more precise readings, the meter needs to be manually set so that the needle is almost at maximum (full scale deflection).

* Possible to read the wrong scale by mistake.

* Scale can be difficult to read.

* Delicate. The needle's mechanism is delicate and accuracy can be affected if the multi-meter is dropped.

Useful features:

* Many measurement ranges. The more ranges available, the better the chances that the meter can be used close to full scale deflection for high accuracy.

* 50 micro amps measurement range. More common is the less sensitive 200 micro amps range.

Auto-ranging Digital Multi-meters

Digital multi-meters are deservedly popular. However users need to be aware of their limitations.

Advantages:

* Accurate. The best DMMs can have accuracies as high as plus or minus 0.1% but 1% to 2% is more common.

* Easy to use. Autor-anging DMMs automatically switch the internal circuit to the correct measuring range.

* Wide range of features. Advanced DMMs can measure waveform frequency and duty cycle (edging into oscilloscope territory).

Disadvantages:

* LCD display can be too dim to read easily. Some models have a back-lit display but this will reduce battery life.

* Not suitable for measuring fluctuations and transients.

* No zero adjustment for resistance measurement, except on advanced models.

Useful features:

* Automatic power-off.

* Back-lit display, with "always on" option.

* Analog bar graph for quick reading of fluctuations. This is a killer feature, available on professional models costing hundreds of dollars. It allows a DMM to have the advantages of both analog and digital meters.

* Selectable auto or manual ranging.

* Display of minimum, maximum and average readings.

* Measurement hold feature.

* Connection to PC for automatic periodic data-logging.

* Automatic AC/DC voltage detection and measurement switching.

* Non-contact AC voltage detector. For identifying live wires.

Other Multi-meter Features and Measurements

The following features are useful for both analog and digital multi-meters:

* True RMS AC voltage measurement.

* Continuity tester with beeping indicator.

* Diode tester with beeping indicator. Also used to test BJT transistors, two terminals at a time.

* Battery tester for 1.5 and 9 volt batteries. Measures voltage while loading the battery with a small current drain. This feature is more common on analog meters.

* BJT transistor gain (hFE) measurement.

* FET transistor gate leakage current measurement.

* Capacitance measurement.

* Temperature measurement with separate thermocouple probe.

* Table stand.

* On-board storage for test probes.

* Fused input circuit.

* Maximum 10 amperes measurement circuit. A separate test probe socket is needed to handle the high current. Cheaper meters use an un-fused input circuit for the 10 amperes socket, even if the other socket is fused.

The Best Multi-meter or Multi-tester:

A basic, low-cost auto-ranging digital multi-meter is easy to use: good for the non-technical DIY hobbyist. More advanced users can handle the complexity of an analog meter, giving them the flexibility of dealing with fluctuating readings.

Professional engineers, technicians and electricians will want to pay more for a digital multi-meter with a bar graph display, allowing them to enjoy the advantages of both types of multi-meters.

Hybrid multi-meters with dual digital and analog displays are a possible alternative.

B)

[chazm 413]

I like digital because of the pretty lights

Hey Mike - what,are ya trying to show up the teacher already

That has that covered ... next lesson

Chaz :clap:

[6wheeler 670]

I use digital mostly because I lost my analog. It definately has more features, but because of that very reason it can be more intimidating also. It seems to me the analog was easier to use. I don't fully understand this meter and I have alot to learn about what it can do, but for simple resistance checks and voltage and such it is pretty straightforward. I paid about 50 bucks for mine at Carquest it will do bars and numbers. you guys doing this tutorial will help meout quite a bit so thanks in advance. Pat

[MikesRJ 558]

Hey Mike - what,are ya trying to show up the teacher already

Ah, Grasshopper, the teacher and I are of the same cut of cloth .. now when you can grasp the pebbles from our hand ...

[Save Old Iron 1,573]

Hey Mike - what,are ya trying to show up the teacher already

Now master Micheal is going to have to stay after class to tell us all how 50ua movements, transistor hfe function and FET transistor gate leakage current measurement have any advantage in fixing a PTO safety switch on a tractor.

:party:

[rmaynard 16,657]

I always liked an analog meter until I got my first digital. I liked it mainly for checking resistance. The digital meter has it's advantages though in that you can have polarity reversed without dipping the meter in the wrong direction. Also digitals won't bury the meter on over-voltage.

In any case, a meter should have an audible continuity checker, probably the most used setting that any of us will use in tracing circuitry.

My 2 cents worth.

Bob

[refracman 167]

Hmm I seem to remember one of my grade school teachers givin me that look before and that ruler looks mighty familar too

I prefer the digital with the option to check voltage by slippin it over the wire. Also have the analog doesn't see much use any more unless of the batteries are dead.

[MikesRJ 558]

aaaaaahhhhhhhhh, EVIL PENGUINS! Visions of parochial school. How dastardly of you!

This would have been much more appropriate:

[pfrederi 19,108]

I like my analog for voltage readings and continuity testing. (Easy to see the needle move..... if I have to read specific resistance levels, however (as in a coil test) I prefer the digital...I get confused with the ohm scales on the analog....

[MikesRJ 558]

The answer is "D": No applicability whatsoever!

The safety switch is either open or closed and one only needs to check the resistance in its two states in order to verify its function, either by electrical actuation or mechanical actuation, as it applies to the particular PTO and the switches integration/configured within.

Class Dismissed!

Now master Micheal is going to have to stay after class to tell us all how 50ua movements, transistor hfe function and FET transistor gate leakage current measurement have any advantage in fixing a PTO safety switch on a tractor.

[sorekiwi 761]

Now master Micheal is going to have to stay after class to tell us all how 50ua movements, transistor hfe function and FET transistor gate leakage current measurement have any advantage in fixing a PTO safety switch on a tractor.

Exactly!

I can read a whole lot of stuff I dont understand if I RTFM!!

[tophatbufflo 2]

save old iron I have an Amprobe, A Fluke digital and a Tuffy digital that I have aquired over the years for use at different jobs. I know the basics but haven't needed to learn any more so I was glad to see what Mike wrote and any thing else that will be added. I have worked too many different jobs that I didn't have to learn more. I now have a lot of spare time so I can get more education for the next job. Thanks for all you guys are doing for us B)

[Confused99 2]

While taking an electronics program in college I bought at Fluke 87 and it saved me a ton of time doing labs over the guys with analog meters. I think if a person has not used a multimeter much if any, a digital one will be more user friendly. The other advantage is some have temp probe leads which can be useful.

Jason

[dodge78 94]

I use one of these. Its cheap at $25 - 30 at various places such as walmart, farn and fleet and couple of others. I see its at $18 on amazon right now. Its auto-ranging, which means I can be a little lazy, or if I get things setup to find out I have it on the wrong setting while under the dash of a car can be a pain. Its rated for 10 amps only but I have others meters for over that.

The Fluke 97 gets brought out only on special occasions.

[Don1977 605]

I'am an old Navy Electronic Technician, I use an Analog, I like a meter that makes up it's mind. I don't need a meter that gives .002 change every .10 of a second.

[Save Old Iron 1,573]

I use one of these. Its cheap at $25 - 30 at various places such as walmart, farn and fleet and couple of others.

Its rated for 10 amps only but I have others meters for over that.

This is actually a decent meter - the only restriction is the statement in the manual for

"The 2A and 10A range is unfused - a maximum testing time of 15s is recommended! For the 10A range a waiting period of at least 15 minutes is necessary between every 15 second testing period! "

I just don't like the unfused part.

This will be covered further once the tutorial starts but imagine

your measuring charging current to the battery - lets say its 10 amps - no problem.

Then you want to measure the battery voltage and forget to change the meter settings off amps to voltage.

When you put the meter (still in amps mode which is essentially a short circuit thru the meter) across the battery leads - 100 amps or more will flow thru the meter and probably fry it ! If it were fused - you would have blown the fuse and generally could replace it.

[Save Old Iron 1,573]

I like a meter that makes up it's mind. I don't need a meter that gives .002 change every .10 of a second.

Ditto here.

although the digitals with a range select can easily be set to read in just xx.x volts - just one decimal place.

This is just fine for the tractor environment when you would never be reading any voltage higher than say 16 DC or 40 V AC.

Lesson here is don't "overbuy" on an expensive feature laden meter. A good solid meter in the 50 - 100$ range is more than enough.

Thanks - this is all great material to be covered in the tutorial.

B)

[Save Old Iron 1,573]

I like digital because of the pretty lights

Somehow I think this whole experience is going to be more of a lesson for me than you guys :party:

[chazm 413]

Now- Now Chuck ,it will be OK

Just as long as you don't go using big old words like ...

resistance, voltage, diodes, transistors, continuity or ohms

I almost forgot... and pics of the pretty lights

Chaz B)

[W9JAB 156]

As one who worked as an industrial control electrician for over 30 years I have a large case of meters, too many to list, and the reason for so Many is that you need special meters for the right application. The secret to not smoking a meter is to know what you are expecting to measure before you choose the meter. don't use an Ohm meter to check for 480v, you will be surprised and the sound it will make.

As far as digital V.S. analog I personally do not like digital for general use as they are so sensitive you may read something that is not there, I.E. I have read R.F. as voltage on a digital meter.

For most D.C. jobs I like the screwdriver style probe with the light inside the handle and ground clip on the wire for tracing power.

Also it's good to have a couple of meters as you will see a slight difference in readings from meter to meter.

B)

[BPC23 18]

Here's what I think. I'm a Mechanical Engineer with a healthy fear of electrical stuff. I've used both types of multimeters. and was intimidated by the analog, despite having built it from a kit. It had too many settings and scales. I much prefer my Radio Shack digital multimeter. I would guess that anyone needing to read an introductory guide to electrical troubleshooting would be mostly using a digital.

[wh500special 2,357]

Interesting discussion and points made.

I didn

[dodge78 94]

I just don't like the unfused part.

Then you want to measure the battery voltage and forget to change the meter settings off amps to voltage.

When you put the meter (still in amps mode which is essentially a short circuit thru the meter) across the battery leads - 100 amps or more will flow thru the meter and probably fry it !

For its price, I would not feel to bad too about it. Its the main reason I bought it, so I would not have to wory to much about dropping, kicking or stepping on the good ones. Or blowing it up.