Hi there,
This turns out to be a pretty nice meter for a mere 20 dollars including tax.
There is one problem though, and that is that the meter bounces quite a bit
on the low ohms scale. This seems to be a problem if you intend to measure
low value resistors like 10 ohm, and especially 1 ohms, or 0.5 ohms. It's
still possible to do like any other meter, but you have to keep an eye on
the display to watch for an upper drift reading with the leads shorted
and again with the resistor connected (see tests below).
(See also tests and measurements taken below)
Features:
1. To start with, this is a 3999 count meter, not just 1999 like most other
meters for this price. This works out nice when measuring the voltage
of Li-ion batteries that are typically 3.000v to 4.200v (see below).
This is a very nice feature.
2. Another nice feature not found on many meters is the "Relative" setting.
This allows making more accurate measurments of voltages outside the count
range, which is impossible with meters that dont have this feature (see below).
This should also have been able to be used for zeroing out the ohms scale
because the typical ohms offset on many meters like this is 0.3 ohms (see below),
but this meter seems to drift on the low ohms scale.
3. The "Frequency" measurement. You can measure frequency with 4 digits,
even at low frequencies like 1Hz, which would read 1.000Hz on this meter.
I measured (or tried to) the frequency of two blinking LEDs, and i got various
readings (because the frequency was changing) one of which was something like
2.892Hz. Of course with this as well as other meters if the frequency isnt stable
it might be hard to get a reading, however i was able to tune my Les Paul remake
guitar string 'A' to exactly 110.0 Hz after connecting the leads to the speaker of
my amplifier. The input level doesnt seem to be sensitive enough to pick up the
raw guitar output like my 100 dollar meter can, but connecting it to the output
of an amp (like headphone jack) seems to work ok...overall i like it.
4. Goes up to 10 Amps dc *or* ac. Having ac is nice here too. Many meters only do
dc. This means you can check home appliances, as long as they dont draw more than
10 amps. One caution however is that you can not leave it connected for more
than 30 seconds, and then you have to let it rest for 15 minutes to allow time
for the internal current shunt to cool down. This is a pain, but at least it has the
10 A scale. Probably at 5 amps you can let it run for 2 minutes.
5. Range Hold and Range Set. Allows you to freeze a reading, or to set the
range to a specific range if you want rather than let it auto range. This is nice
for measurements that change near the crossover point, so the reading doesnt bounce
from say 3.999v to 4.01v, which gets annoying without being able to set it to the
higher range. One of my other meters auto ranges and it bounces sometimes and
that's really a pain, expecially since it also beeps each time ! <chuckle>
6. Also does capacitors from about 10pf up to 200uf. Many people will not use
this however.
7. Measures temperature, but doesnt come with the thermocouple probe! That's
too bad, but then the one Sears sells only goes up to 260 deg C anyway, so better
get it somewhere else and get up to 500 deg C or better. The meter itself will
measure up to 760 deg C with the correct probe (Sears doesnt seem to sell).
8. Diode and continuity tests. Max output is 1.6v so it will not test white
or most blue LEDs. It will test the standard red leds but only if they
emit enough light at 1.6v forward voltage (some do some dont), as it will
not give an actual reading with any LED (constantly reads OL which means the
reading is too high for the meter to handle).
9. Auto power off after 15 minutes. Saves the batteries (two AAAs) if left on.
10. The 'Duty Cycle' option. This measures duty cycle of a wave,
probably has to be a rectangular wave.
Comparative Measurements:
TEST #1 -- Li-ion cell under 4v
-------------------------------------------------------------------------
$100 meter: 3.75v (count only goes to 1999 so higher range had to be used)
Craftsman: 3.73v on same range as $100 meter, but 3.745v on best range
This means the Craftsman can read Li-ion batteries better. Yes, Li-ion
cells can go as high as 4.200 volts and the Craftsman can only read up to
3.999v on the best range, so this is where the Relative setting comes into
play...
Say our cell under test measures 4.20 volts on the higher range (cant get 4 digits
yet). If we instead first connect a 1.200 volt battery across the leads, wait
for the reading of 1.200 volts, then press the "Relative" button, the reading
is stored as a tare reading which zeros out the meter at 1.200 volts. Now
we disconnect that cell and connect up the 4.200v cell again only now we read
3.000 volts. What it does is take the 1.200v and subtracts it from the
real voltage of the Li-ion cell (4.200v) and displays the result: 3.000 volts.
Pretty nice if you ask me, because now we can read the millivolts whereas with
the other meter (the $100 one) we cant because it has to be set to the range
where the cell reads 4.20 volts (note no millivolts show up).
This works out very nicely for the Craftsman meter, although in practice
our 'reference' cell of 1.200v will probably be more like 1.243v or some
odd voltage like that, so we will have to do some subtraction in our head
unless we use a pot to divide the voltage down to exactly 1.200v, or even
1.000v, whichever is easier at the time.
TEST #2 -- NiMH cell
-----------------------
$100 meter: 1.359v
Craftsman: 1.356v
TEST #3 -- leads shorted ohms
-----------------------------------------------------
$100 meter: 0.1 ohms constant
Craftsman: drifts 0.3 ohms to 0.5 ohms and back again.
TEST #4 -- 100 ohm, 5% tolerance resistor
--------------------------------------------------------
$100 meter: 98.2 ohms constant
Craftsman: drifts 98.5 to 98.7 ohms and back again
Craftsman after taring 0.4 ohms with the Relative button: drifts 98.0 to 98.2
TEST #5 -- 200 ohm, 5% tolerance resistor
----------------------------------------------
$100 meter: 198.0 constant
Craftsman: drifts 197.5 to 197.7 ohms. Sometimes drifts 197.4 to 197.8 ohms.
TEST #6 -- 4.7k, 5% tolerance resistor
------------------------------------------
Drift went away as soon as the meter changed to the next higher up resistance
range. Readings were close.
TEST #7 -- 0.47 ohm 10% tolerance power resistor
------------------------------------------------
$100 meter: 0.6 ohms (remember the 0.1 ohms offset of this meter)
Craftsman: drifts 0.7 to 1.0 ohms. The only way to compensate for this
drift is to measure the short circuit resistance (leads shorted) and
watch for the upper drift ohms and then measure the 0.47 ohm resistor
and watch for the upper drift again, and subtract the tare from the
reading. Doing this would give the same for both meters: 0.6 ohms,
but it's a bit of an annoyance to say the least.
CONCLUSIONS
1. The Craftsman reads about the same voltage as the more expensive
meter.
2. The Craftsman has an annoying bounce on the low ohms scale.
3. The diode test will not test white or blue LEDs.
4. The temperature probe is not included.
5. The frequency and duty cycle features are nice.
6. The 'Relative' button can be very very handy for measuring
voltages that cross a range boundry were you really want one
more digit in your reading. Also can be used to quickly compare
voltages around the same point such as a group of batteries
that are almost the same voltage.
GENERAL CONCLUSION
It's probably worth 30 dollars. The way it works and the overall
feeling you get is that you are working with a 30 or 40 dollar
meter except for the low ohms range, which gives you the feeling
you are working with a meter that was not even designed properly.
