We had similar problems... trying to buy meters for less than $20 and
not having them hold up.
We switched to Beckman, Wavetek, Meterman about 10 years ago and have
had good luck with them. I listed three names because the very same
meters have gone through at least three name changes.
Most of the meters used in our calculus-physics labs are model 15XL. We
have about 20 of these. The oldest ones say Beckman Instruments, the
medium-old ones say Wavetek, and the newest ones say Meterman... but
they are nearly identical other than that. This particular model, which
used to cost $49 was just about perfect. I think only one died in the
past 10 years when a student tried to measure the voltage on a van de
Graaff generator.
Unfortunately model 15XL is discontinued. The replacement is model 15XP
for $59.95, a 20% price jump. There are improvements for that price.
The 15XP is autoranging while the 15XL is manual. I actually prefer the
manual, so this "improvement" does not make me happy. The new model has
auto shutoff after 10 minutes. This is a big plus and can be a real
battery saver. The old model DC current ranges jumped from 200 mA to
10A, whereas the new one jumps from 200 mA to 2 amps. This is a big
plus because it is common to want to measure currents in the 200 mA to 2
A range, and I don't like the loss of resolution when using a 10-amp
scale for measurements less than 2 A. I suspect we will buy some 15XP
and see how we like them.
There is also a new model, the 5XP, for $39.95. That's considerably
less expensive. Here is what you give up... Model 5XP is not
autoranging, its accuracy is 1% rather than 0.5%, the top current range
is 200 mA, it does not auto shutoff. I like the manual range, and I
don't mind the 1% accuracy, but I hate to give up the 2A range. Also,
the loss of auto shutoff could use enough batteries to make the 15XP
less expensive in the long run unless you have better luck getting
students to turn off meters than we have.
In our physical science labs we did not want to spend the money for the
15XL and now not the 15XP. But we had really bad luck with cheap
meters. We finally bought some Meterman DM2 meters which cost $29.95.
Even though this is substantial, I am sure we have saved money over the
throw-away $10 models. There are two problems with the DM2 which make
it less than ideal for the regular physics labs... the top current range
is 200 mA, and the input resistance on the voltage ranges is only 1
megohm whereas typical good digital meters are 10 megohm. However, for
physical science, these meters work and have really held up well. No
damage (other than fuses) in 24 units in service for 6 or 7 years.
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu