My first multimeter

Discussion in 'General Electronics Chat' started by Macnerd, Apr 24, 2015.

  1. Macnerd

    Thread Starter Member

    May 22, 2014
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    I retired in February 2014. I want to take up electronics as a hobby. One of the first things that I need is a multimeter. I went to a Radio Shack store this afternoon & looked at digital multimeters. There were 2 brands - Extech(which I've never heard of) &, of course, Radio Shack. There was an Extech on sale for $45 & a Radio Shack for $45. The Extech has 8 functions & the Radio Shack has 42 functions. I thought to myself that the Radio Shack one is a better deal because it has 42 functions whereas the other has only 8 functions. A customer explained to me why the Radi0 Shack seems to be a better deal. He said that Radio Shack multiplies the number of functions times the range per function to get 42.
    What should I look for? I want the basics - resistance, capacitance, current & voltage. One of them has a diode check feature. Obviously, one can check & see if an LED is working by connecting it to a voltage source. How does the meter check to see if a "regular" diode is working or not? Does the meter check for voltage or current or resistance or what? Should I get a meter that has the ability to check that a diode is working? Should I get an auto-ranging meter? The Extech can measure temperature.
    Radio Shack hasn't completely gone belly-up, but I wonder about buying a meter from them. I'm sure that a Fluke meter would cost an arm & a leg. Do you have any recommendations on brand & where I buy a meter? I can buy online, but I'd rather go into a store & actually hold the meter in my hands.
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    You are already making a number of mistakes but luckily for you, you have come to the right place.

    Don't judge a unit by its price or number of functions.
    Get the unit that provides ALL the functions you need.
    Give us the brand and model number so that we can better guide you.

    You cannot test an LED by connecting it to a voltage source. That is a sure way of blowing the LED.

    DMMs test diodes by presenting a limited current and measuring the forward voltage drop across the diode.

    Not all meters will measure capacitance, frequency, temperature, transistor current gain, etc. You have to decide what is essential and what are extras. We can help you make those kinds of decisions.
     
  3. dl324

    Distinguished Member

    Mar 30, 2015
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    Congrats!
    Since you're just starting out, why not get one of the "free" ones from Harbor Freight. They're around $15 if you buy, but you can get a free with any purchase from the Sunday paper. Once you find out what additional functionality you need, buy another.
    Diode check on a multimeter applies a current limited voltage to the diode and measures forward voltage. The voltage should be high enough to light LEDs. Probably won't work on white LEDs.
    Yes. The HF free meter has diode and hfe check.
    Personally, I don't like autoranging meters. They're too slow.
    But you need to carry the probe around; I rarely use that function on my one meter that has it. I prefer to use a thermometer to measure temp.
    I've never had a digital multimeter stop working. I still have my first multimeter (RCA analog); though I did burn up a resistor once.
    If you don't limit yourself to new and local, you can get HP or Fluke meters inexpensively. I have half a dozen multimeters for my bench. I even have a multimeter plug-in for my Tek 7K series scopes.
     
    absf likes this.
  4. Roderick Young

    Member

    Feb 22, 2015
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    168
    Day to day, all I use is a $5 meter like the Harbor Freight one mentioned above. When I was in my teens and had no money, I got by with an analog meter for years. So I second Dennis - get something cheap, and expand when you know you need something more.
     
    absf, wayneh and cmartinez like this.
  5. #12

    Expert

    Nov 30, 2010
    16,267
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    I'm going to try to simplify this. Get a cheapo for your first meter.
    What the heck, get two. They're free on Sundays.

    You are not qualified to know what you need...yet. Blow up a cheap one, or wear it out, but don't expect to know everything you need and how good it has to be on your first try. It's expensive to outgrow your meter. I was working as a pro for 7 years before I laid down the big bucks, but the result is, I had enough time to see where my interests led me and I knew what I'd need in the long run. That's my recommendation. Maybe not that you should work for 7 years before you choose a good meter, but gee, not on the first purchase!
     
  6. PackratKing

    Well-Known Member

    Jul 13, 2008
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    You cannot test an LED by connecting it to a voltage source. That is a sure way of blowing the LED.

    Not so... Any LED can be illuminated briefly, by placing contacts on a 3v lithium "coin" battery... I haven't killed one in that manner since LEDs hit the market how long ago "??
     
  7. #12

    Expert

    Nov 30, 2010
    16,267
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    Naming the exception to the rule doesn't help beginners.
     
  8. Macnerd

    Thread Starter Member

    May 22, 2014
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    I looked at the Craftsman meters & their display reads 3.999. Some of the specs I've seen state that the display reads 1.999. Why not 9.999?
    I'm going to check out Amazon & Jameco Electronics websites.
     
  9. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
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    I will stick with my Fluke and Uni-t 61E meters..
     
  10. dl324

    Distinguished Member

    Mar 30, 2015
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    Displays that read 1.999 are called 3 1/2 digit displays and are cheaper to make than displays that will display 4 digits; they're also slightly narrower. Three and a half digits has been the standard for many decades.
     
  11. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
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    At work we have a variety of multimeters but the ones that get the most use are the $20-$50 autoranging cheapies because we rarely need the precision or special features of the $400 model.

    My personal meter is one of those expensive models that I've had for 14 years now and it was chosen because it had a larger range of capacitance measurement and because I needed to impress an idiot client with the quality of my gear (never underestimate the value of window dressing when being employed by the ignorant). Before that, I used a very basic analog meter that I got for free and it lasted me 24 years. I have a second $50 digital meter that was thrown away by some subcontractor idiots on a job because they'd destroyed the leads. It cost me $7 for a new set of leads.

    I hope you're seeing a trend here but if you want to immerse yourself in the comparative qualities of multimeters, take a look at the relevant episodes of the eevblog.
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,100
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    Once you get your cheap/free meter (I have at least a half dozen I got for free at Harbor Freight), a project you might look into is a kit to build yourself an ESR meter. These are useful for testing capacitors, which are a common source of failure in ... almost everything that contains them.

    There was a thread here on a very cool kit that wasn't very expensive - I'll see if I can find it.

    Success! Here it is.
     
    Last edited: Apr 25, 2015
  13. WBahn

    Moderator

    Mar 31, 2012
    17,726
    4,788
    I concur with the prevailing opinion here. As a hobbyist starting out, you don't need much at all. A voltmeter and a resistance meter will probably do you fine for years. Being able to measure current is nice, but a lot of newbies get into trouble because they don't understand how to properly, and safely, take current measurements nor do they realize the degree to which most ammeters influence the circuit in which the measurement is being taken.

    Better than having one good meter is having several cheap meters. It is often very handy to be able to measure several voltages in a circuit at the same time, not to mention having the back-up on hand so that when a meter bites it (usually due to dead batteries, but perhaps because you tired to make a current measurement without knowing how to do it properly).

    As you gain some experience you will be in a better position to judge what else you need in a meter, how badly you need it, how good you need the measurement to be, and how much it is worth to you. You'll also be at a point where you can consider building your own meter, either to have a meter that truly matches or needs or just for the enjoyment and learning that goes along with doing so.

    I have on Fluke (that I got for free), but I seldom use it. I have two Micronta (Radio Shack) meters that do everything I need (almost, would love if one of them measured inductance), one of which I have had for nearly forty years and is me favorite meter of the ones I own, and I have a half dozen or so cheap ass meters of the Harbor Freight genre. One goal I have for this summer is to build up identical took kits to put in each vehicle (supplemented as appropriate on a vehicle-specific basis) and each one will a cheapo meters in it.
     
  14. upand_at_them

    Active Member

    May 15, 2010
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  15. ian field

    Distinguished Member

    Oct 27, 2012
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    I agree with that, get something at a low price to be going on with - eventually you'll be wishing the meter had certain other ranges, then you'll know what ranges to look for when shopping for something permanent.

    Once you have a "pride and joy" instrument to cherish, you can leave the cheap one in the shed so you don't have to take the good one there.
     
  16. cornishlad

    Member

    Jul 31, 2013
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  17. dl324

    Distinguished Member

    Mar 30, 2015
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    One nice thing about analog meters is that they only need a battery for resistance measurements. I have cheapie Radio Shack analog meters in 2 of my car breakdown kits. I don't even bother to put batteries in them...
     
  18. Macnerd

    Thread Starter Member

    May 22, 2014
    37
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    I did some research. Mastech meters are made in China. I don't want any of my money going to a country that violates human rights. OK, I'm off of my soapbox.

    One website I visited recommended getting a calibratable DMM.

    I don't want a Fluke because even the basic ones cost over $200. I want to keep the cost under $200 for my 1st DMM. I checked out the Craftsman DMMs. Ehhh. Radio Shack. Ehhh. I want some thing that's durable. The more research that I do, the more confused I get! I want the basic measurements-resistance, voltage, current & capacitance. Inductance. Not sure. At this point maybe I'll get either a Klein tools or an Extech. Both are made in the good ol' USA.
     
    Last edited: Apr 29, 2015
  19. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Somewhere I have an old Taylor 100k/V multimeter.

    The 30V battery bacame unobtainable, so I copied the inverter from a gas ignitor with suitably adjusted secondary turns. Simply shunted the rectifier/reservoir with a 30V zener. The circuit assembly fit easily in the compartment for the 30V battery, its powered by the 1.5V cell for the low Ohms range via a push button.

    Unfortunately I dropped a pair of pliers on the glass - it now has a window cut from a motorcycle visor superglued on.
     
  20. Macnerd

    Thread Starter Member

    May 22, 2014
    37
    1
    One website I visited recommended getting a calibratable DMM.
    Calibratable DMMs are more expensive. If I get a non-calibratable DMM, how will I know that it is out of calibration? Obviously, the money that I spend to get a new non-calibratable DMM can be spent getting a calibratable DMM calibrated!
     
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