Multimeter Advice

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networkn

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#112962 29-Dec-2012 20:48

Hi There!

I am looking for some advice on what to spend on a multimeter and if it's likely bunnings (The closest discount retailer to me) will have what I need.

I am building a DIY headphone Amp and I need to measure resistance.

Recommended by the manual is Volt Ohm Meter called a Pocket DMM.

I don't want junk but I also don't use multimeters very often and so I don't want to spend the earth.

Anyone got a recommendation or perhaps a price range I should be looking to cover?

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#738423 29-Dec-2012 21:34

My career since the 1970s has been electronic servicing. Have used a wide range of MMs over that time. Naturally as its my job I use high end gear but the cheap $35 type MMs seem to work ok for occasional use. Not sure if Bunnings sell meters but I'm sure Repco, Supercheap, sell cheap meters. A cheap meter is all you need for your project as its accuracy will be adequate at that price point.

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#738426 29-Dec-2012 21:51

BrianP: My career since the 1970s has been electronic servicing. Have used a wide range of MMs over that time. Naturally as its my job I use high end gear but the cheap $35 type MMs seem to work ok for occasional use. Not sure if Bunnings sell meters but I'm sure Repco, Supercheap, sell cheap meters. A cheap meter is all you need for your project as its accuracy will be adequate at that price point.

Thanks for the reply. Would you have 30 seconds to find a suitable link ? There seems to be a massive quantity of options with varying voltage ranges etc.

BrianP

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#738431 29-Dec-2012 22:07

From your description of your needs this looks like its suitable.

http://www.supercheapauto.co.nz/online-store/products/Stanley-Multimeter-Digital-Pocket.aspx?pid=9441#Description

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#738433 29-Dec-2012 22:11

BrianP: From your description of your needs this looks like its suitable.

http://www.supercheapauto.co.nz/online-store/products/Stanley-Multimeter-Digital-Pocket.aspx?pid=9441#Description

Thank you very much for your assistance.

It's a Tube Headphone Amp that plugs into the mains (with a big as transformer). I presume this one is mains rated?

BrianP

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#738437 29-Dec-2012 22:23

Yes I wondered if it was a Tube HP amp. They seem quite popular at the moment.
Hope you're going to personalise it. Steampunk maybe?
That meter will be fine on the higher AC / DC volts. I see its good for up to 500 VAC and 500VDC which will cover the voltages present in a tube type device.

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#738440 29-Dec-2012 22:30

BrianP: Yes I wondered if it was a Tube HP amp. They seem quite popular at the moment.
Hope you're going to personalise it. Steampunk maybe?
That meter will be fine on the higher AC / DC volts. I see its good for up to 500 VAC and 500VDC which will cover the voltages present in a tube type device.

Thanks so much.

This is what I bought:

http://www.bottlehead.com/store.php?crn=224&rn=442&action=show_detail

I am really enjoying the very early stages of assembly. My Grandfather was an electronics enthusiast and worked for the dsir and many other places over the years. He bought me my first electronics kit back when Dick Smith sold them and not printers and other premade electronic items. He taught me to solder and I will be getting a plaque made up with "dedicated to..." on it.

I would love to get a black lacquer look, and I would really like to make it look nicer than it does stock, but I'll get the basic parts done first and then consider my other options.

mattRSK

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#738442 29-Dec-2012 22:39

Here is a useful document regarding multimeter safety.

http://support.fluke.com/educators/Download/Asset/2096653_6003_ENG_D_W.PDF

gzt

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#738501 30-Dec-2012 09:44

I have not used an MM regularly for years. The cheaper ones may not last in the probe area. In many of the cheap ones the probes are not replaceable. I had a look quick look recently for another geekzone thread.

For what it is worth my picks would be these:

Robust workshop meter: $155. IP67 with wireless USB: $135. IP 67: $99.

#1 has a bar graph which in theory is nice to see the detail of a fluctuating voltage or current and mimics the level of detail given by the old analog style meters. Rapidly cycling digits cannot really compete and make no sense. That detail is not needed often but when I moved from analog to digital I really missed it. #2 with wireless USB just looks really cool for logging measurements over time. If I bought it I would find all kinds of marginal uses for it lol. : ). #3 is without the usb feature.

Buy at least one fuse at the same time. They are specialist items and if you blow one you can bet it will be very inconvenient.

Probes are important. I find spring hooks the most useful type can be clipped to all kinds of components and no need to hold them in place while performing other actions and watching the meter. Jaycar's selection of probe accessories is not that good for some reason. I would stay away from the hooks with banana sockets in the ends.

For a general purpose hobby meter long leads and hooks are the way to go. For standard probes get these protected ones to avoid expensive shorts resulting from attempted use of probes in tight spaces.

I'm not a professional like BrianP at all but I hope the hobby experience is useful all the same.

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#738529 30-Dec-2012 11:04

gzt: thanks for the reply. No way can I justify spending more on the MM than the hobby project itself, especially since I do one of these about every 5 years and have no use in between of any significance.

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#738615 30-Dec-2012 16:57

They didn't have the $25 at the SCA that I went to, so I had to buy the next cheapest which was a smaller more portable version of the same thing, which was $39 which is ok.

BrianP

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#738619 30-Dec-2012 17:30

That's ok. $25 seemed a bargain. Don't know how they can retail them in NZ so cheap.
Now safety in use is to be considered, I guess I'm a bit blaise about it due to using one most every working day.
Probably the worst thing that can happen (apart from electrocution, believe me it hurts) is slipping with the probes whilst taking a measurement. You can minimise this being a problem by slipping on some stripped wire insulation over the metal probes so only the tips are exposed. Also keep the tips sharp so they have an edge to bite into the measurement point.
Have fun and if you get stuck with a non working project feel free to contact me thru my email. Cheers.

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#738631 30-Dec-2012 17:41

BrianP: That's ok. $25 seemed a bargain. Don't know how they can retail them in NZ so cheap.
Now safety in use is to be considered, I guess I'm a bit blaise about it due to using one most every working day.
Probably the worst thing that can happen (apart from electrocution, believe me it hurts) is slipping with the probes whilst taking a measurement. You can minimise this being a problem by slipping on some stripped wire insulation over the metal probes so only the tips are exposed. Also keep the tips sharp so they have an edge to bite into the measurement point.
Have fun and if you get stuck with a non working project feel free to contact me thru my email. Cheers.

Hi There!

Thanks for the advise. I am hoping to avoid electrocution, that would be a sucky end :)

Sorry I don't know what you mean by stripped wire insultation?

Also I was a little annoyed with this MM as it doesn't mark which is red and black on the MM itself but both probe connectors are red!

There are 3 holes in the MM one which is 10Amax Second which is V(ohms)A and one which says COM.

It would seem whatever you are measuring it's different probes in different holes!

I hate not knowing stuff, and I have to say that this seems very complicated!

Technofreak

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#738660 30-Dec-2012 18:41

Most likely the "Com" or Common Connection will be negative. Use the Com and one of the other connections to put the leads into. You will mostly use the V/Ohms/A socket and select the type of measurement and range with the rotary switch.

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gzt

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#738675 30-Dec-2012 19:03

When in current measurement mode (and 10A range socket) the meter is essentially a short circuit. ie; as if the probes are connected/wired together. Short circuiting a current source is a really bad idea.

Bizarre having two red leads. Maybe a packing mistake? DMM's are just as happy reading negative tho. I'd put some black tape or indelible mark on both ends of one of those leads just so I know what the meter is telling me.

If it's not too late take it back to supacheap and get something better from jaycar before it gives you more regret :-p)

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#738678 30-Dec-2012 19:14

I purchased one of these http://dx.com/p/2-0-lcd-digital-multimeter-with-silicone-case-1-6f22-included-29256
Works well, and has a decent backlight which is very handy. It is actually far better than one I paid significantly more for many years ago from a local retailer, and was poor quality. The only downside is that you have to wait weeks to get it. However there are people selling them on trademe, which will mean only a few days of waiting, but paying more. Many of the cheap ones I saw in local retailers just look to be chinese imports anyway, so I went to the source instead. They do have a big selection, but read the reviews first.

edit: having two red leads on a multimeter isn't good, and possibly shows quality control problems. I would return for a refund and buy something better.

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