CHAPTER 4 ■ DIGITAL MULTIMETER
Optical USB data output This meter has a USB cable, unlike older multimeters that require a PC with a
now-obsolete RS-232 port. The other end of the USB cable connects optically
to the meter—which means the information is transmitted with light rather
than an electrical connection. This avoids problems with the computer or
household power contaminating the meter readings. The meter comes with
the PC software, rather than being available separately for an additional
cost. (Most commercial multimeter software is written only for Microsoft
Windows. Keep that in mind if you use Linux or a Mac.)
Complete with integrated
protective holster, zipper
pouch, and high-quality
test leads
It’s important to check to see if these items are included. Some higher-end
meters require you to purchase these items separately.Interestingly, like most higher-end meters but unlike most mid-range meters, this doesn’t include a
transistor socket or temperature measurement. The more expensive meters focus on accuracy and precision
(number of digits) instead of trying to be all-in-one tools. In fact, laboratory professionals often use highly
accurate, highly specialized stand-alone tools (a voltmeter, an ammeter, an LCR meter, and so on) rather
than combination multimeters.
Comparing Prices with Features
Here are the prices I paid for the digital multimeters, including shipping:
$6.50 - Low-end DT-830B$32.00 - Mid-range VC97$165.00 - Higher-end VA38Honestly, $6.50 for a digital multimeter! The least expensive meter would be acceptable for someone on
a budget or as a spare. Just don’t expect it to last very long. It measures the most important attributes with
reasonable accuracy, although you will miss capacitance and frequency measurement. Often times, low-end
meters like this are given away for free with a certain-size order. Look for those deals before actually buying a
cheap meter.
The mid-range meter includes almost everything you could ever want for amateur robotics. You may
have to hunt around on eBay to find this price, or expect to pay closer to $50. If you can afford to do so, aim
to purchase an autoranging meter with these types of features. It will significantly increase your productivity
and satisfaction.
The higher-end meter is very accurate. It’s definitely constructed out of higher-quality materials.
However, the resolution and accuracy are wasted, since only rough values are necessary for building, testing,
and debugging homemade robot circuits.
Even more expensive meters with (believe it or not) fewer features are available. Those ultra-high-end
meters (> $1000) provide amazing resolution and accuracy at a steep price. For certain specialized tasks,
these certified meters are indispensable. However, for most people, a moderately priced multimeter and
moderately priced oscilloscope would be a better purchase.