Choosing a multimeter

Hi,
I'm just starting out with electronics and I need a cheap multimeter or
a separate voltmeter and milliameter. For the project I'm working on they
say I need:

1) milliameter: range microamps to 100 milliamps or so.
2) voltmeter: range 100 microvolts to 3+ volts.
sensitivity 20,000 Ohms per Volt.

I'd prefer to get two different meters rather than a multimeter. If someone
could point me towards meters that have at least these
specs that would be wonderful.

Thanks.

 

The latter is a conventinal analogue (moving coil) meter. Radio Shack
used to sell an assortment of them.
However, I doubt very much that you will find one which is just a
multi-range voltmeter. They will all have current and resistance
ranges too.

 

I bought several DMMs from Futurlec for $6 apiece. The test leads
were bad on one, but the meter itself worked okay, even came with a
battery(!) At that price, you could afford several.

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The lastest Harbor Freight (print) catalog has item 30756-4JKA
3 1/2 digit DMM for $2.99 each.
DC-A: 0-200uA, 2mA, 20mA, 200mA
Resistance: 0-200, 2K, 20K, 200K, 2000K
DC-V: 0-200mV, 2V, 20V, 200V, 1000V
AC-V: 0-200V, 750V
Also diode, continuity, and transistor test.

Last time they were this cheap I bought 5 of 'em.
They are really handy and no worries if you drop it.
I also have in mind that next time I need a panel meter,
this may be the cheapest way to go!

Don't know if the Web catalog has the same price
<www.harborfreight.com>.



Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

Bob, look at this panel meter. Finally, one that has a built in Dc-DC
converter so it will run off +5 volts, or a 9 volt battery without
isolation.

http://www.mpja.com/viewallpict.asp?dept=52&main=51 14505 ME $8.95 each

Compact, 3-1/2 Digit, reflective LCD Digital panel
meter with black plastic bezel & face plate. Chip On
Board design for economy as well as compactness.
Ideal for battery powered monitoring or test equipment.
RANGES: (jumper selected)
ADC: 200mA
ACV: 200mV/2V/20V/200V/500V
VDC: 200mV/2V/20V/200V/500V
Selectable Power: 9VDC (Isolated power) or 5VDC
(input & power common Ground)
1/2" character height Adj. decimal point
Auto polarity >100Mohm input imp.
2 readings/sec., .8% accuracy (1% AC)
Through panel mounting.
W: 2-5/8" H 1-3/4" D: 3/8" WT: .1

It looks interesting to me. If it was a 4 1/2 Digit it would be even
better! Then they would be perfect for a bench power supply to monitor
voltage or current at the flip of a switch..

 

I need a cheap multimeter

I got some cast-off Sears analog units at http://www.acpswapmeet.com/
(only happens 1 day out of 60).
Repaced the fuse(s) and good to go.
Needles are nice for watching trends.

I get mailers from http://www.harborfreight.com/
They often have DMMs under $4 on special.
You may have a similar tool outlet near you.

Your local version of http://www.recycler.com/
(magazine where folk sell their old stuff) may do you.

Used stuff on ebay is another option.

Unless you can get surplus meter movements
(the cheapest new ones are $20), get 2 cheap multimeters.

 

That 200 mV AC range looks especially good. That's one area that
cheap DMMs always come up short. Thanks for the tip!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

Bookmark that page for the next time someone complains that they
can't use a regular panel meter because of isolation problems. I am
going to add it to a construction tips page for my website.

I am designing a new five output bench power supply where I am
debating on using these, or a LCD panel to display all four adjustable
supplies, and the fixed 5 volt supply. It would be cheaper to use the
modules, but will look better with a single, formatted display.

 

On Wed, 21 Jan 2004 17:48:52 GMT, "Michael A. Terrell"

Don't mind me butting in because I've been trying to get some decent
one cheap. Local prices seem to be around US$60 minimum and so 9 bucks
sound really good.

What does 3 1/2 digit means? that it will display 4 digits but the
last one can't be trusted?

Would 2Hz sampling be a bit slow? It would happily miss a 50% spike
that lasts for 300msec right?
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LOL... No, 3-1/2 digit means that there are 3 whole digits, plus a fourth
one which only displays 0 and 1, hence the maximum number displayed can go
up to 1999 (plus sign and decimal point). There are also 3-3/4 digit
displays which can display up to 3999. A full 4-digit display would go up to
9999.

Probably yes, but not necessarily. A multimeter may display 2 readings/sec,
but may actually sample much faster than that. I have a Fluke 189 multimeter
which can catch pulse widths down to 250 microseconds. But this is a very
expensive multimeter, cheap ones may well miss short duration spikes.

Costas